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RIOT/cpu/esp32/doc.txt
Gunar Schorcht 24162af90a cpu/esp32: small doc fix
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/*
* Copyright (C) 2018 Gunar Schorcht
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
@defgroup cpu_esp32 ESP32
@ingroup cpu
@brief Implementation for Espressif ESP32 MCUs
@author Gunar Schorcht <gunar@schorcht.net>
\section esp32_riot RIOT-OS on ESP32 boards
## Table of Contents {#esp32_toc}
1. [Overview](#esp32_overview)
2. [Short Configuration Reference](#esp32_short_configuration_reference)
3. [MCU ESP32](#esp32_mcu_esp32)
1. [Features of ESP32](#esp32_features)
2. [Features Supported by RIOT-OS](#esp32_supported_features)
3. [Limitations of the RIOT-port](#esp32_limitations)
4. [Toolchain](#esp32_toolchain)
1. [RIOT Docker Toolchain (riotdocker)](#esp32_riot_docker_toolchain)
2. [Manual Toolchain Installation](#esp32_local_toolchain_installation)
5. [Flashing the Device](#esp32_flashing_the_device)
1. [Toolchain Usage](#esp32_toolchain_usage)
2. [Compile Options](#esp32_compile_options)
3. [Flash Modes](#esp32_flash_modes)
4. [ESP-IDF Heap Implementation](#esp32_esp_idf_heap_implementation)
6. [Common Peripherals](#esp32_peripherals)
1. [GPIO pins](#esp32_gpio_pins)
2. [ADC Channels](#esp32_adc_channels)
3. [DAC Channels](#esp32_dac_channels)
4. [I2C Interfaces](#esp32_i2c_interfaces)
5. [PWM Channels](#esp32_pwm_channels)
6. [SPI Interfaces](#esp32_spi_interfaces)
7. [Timers](#esp32_timers)
8. [RTT Implementation](#esp32_rtt_counter)
9. [UART Interfaces](#esp32_uart_interfaces)
10. [CAN Interfaces](#esp32_can_interfaces)
11. [Power Management](#esp32_power_management)
12. [Other Peripherals](#esp32_other_peripherals)
7. [Special On-board Peripherals](#esp32_special_on_board_peripherals)
1. [SPI RAM Modules](#esp32_spi_ram)
2. [SPIFFS Device](#esp32_spiffs_device)
8. [Network Interfaces](#esp32_network_interfaces)
1. [Ethernet MAC Network Interface](#esp32_ethernet_network_interface)
2. [WiFi Network Interface](#esp32_wifi_network_interface)
3. [WiFi SoftAP Network Interface](#esp32_wifi_ap_network_interface)
4. [ESP-NOW Network Interface](#esp32_esp_now_network_interface)
5. [Other Network Devices](#esp32_other_network_devices)
10. [Application-Specific Configurations](#esp32_application_specific_configurations)
1. [Make Variable `CFLAGS`](#esp32_config_make_variable)
2. [Application-Specific Board Configuration](#esp32_application_specific_board_configuration)
3. [Application-Specific Driver Configuration](#esp32_application_specific_driver_configuration)
11. [Debugging](#esp32_debugging)
1. [JTAG Debugging](#esp32_jtag_debugging)
2. [QEMU Mode and GDB](#esp32_qemu_mode_and_gdb)
# Overview {#esp32_overview}
The **RIOT port for Xtensa-ESP** is a bare metal implementation of **RIOT-OS**
for **ESP32** SOCs which supports most features of RIOT-OS. The peripheral
SPI and I2C interfaces allow to connect all external hardware modules supported
by RIOT-OS, such as sensors and actuators. SPI interface can also be used
to connect external IEEE802.15.4 modules to integrate ESP32 boards into a GNRC network.
Although the port does not use the official **ESP-IDF** (Espresso IoT
Development Framework) SDK, it must be installed for compilation. The reason
is that the port uses most of the **ESP32 SOC definitions** provided by the
ESP-IDF header files. In addition, it needs the hardware abstraction library
(`libhal.a`), and the **ESP32 WiFi stack binary** libraries which are part
of the ESP-IDF SDK.
[Back to table of contents](#esp32_toc)
# Short Configuration Reference {#esp32_short_configuration_reference}
The following table gives a short reference of all board configuration parameters used by the ESP32
port in alphabetical order.
<center>
Parameter | Short Description | Type[1]
----------------------------------------|-------------------------------------------------------------------|------
[ADC_GPIOS](#esp32_adc_channels) | GPIOs that can be used as ADC channels | m
[CAN_TX](#esp32_can_interfaces) | GPIO used as CAN transceiver TX signal | o
[CAN_RX](#esp32_can_interfaces) | GPIO used as CAN transceiver RX signal | o
[DAC_GPIOS](#esp32_adc_channels) | GPIOs that can be used as DAC channels | m
[I2C0_SPEED](#esp32_i2c_interfaces) | Bus speed of I2C_DEV(0) | o
[I2C0_SCL](#esp32_i2c_interfaces) | GPIO used as SCL for I2C_DEV(0) | o
[I2C0_SDA](#esp32_i2c_interfaces) | GPIO used as SCL for I2C_DEV(0 | o
[I2C1_SPEED](#esp32_i2c_interfaces) | Bus speed of I2C_DEV(1) | o
[I2C1_SCL](#esp32_i2c_interfaces) | GPIO used as SCL for I2C_DEV(1) | o
[I2C1_SDA](#esp32_i2c_interfaces) | GPIO used as SCL for I2C_DEV(1) | o
[PWM0_GPIOS](#esp32_pwm_channels) | GPIOs that can be used at channels of PWM_DEV(0) | o
[PWM1_GPIOS](#esp32_pwm_channels) | GPIOs that can be used at channels of PWM_DEV(1) | o
[SPI0_CTRL](#esp32_spi_interfaces) | SPI Controller used for SPI_DEV(0), can be `VSPI` `HSPI` | o
[SPI0_SCK](#esp32_spi_interfaces) | GPIO used as SCK for SPI_DEV(0) | o
[SPI0_MOSI](#esp32_spi_interfaces) | GPIO used as MOSI for SPI_DEV(0) | o
[SPI0_MISO](#esp32_spi_interfaces) | GPIO used as MISO for SPI_DEV(0) | o
[SPI0_CS0](#esp32_spi_interfaces) | GPIO used as default CS for SPI_DEV(0) | o
[SPI1_CTRL](#esp32_spi_interfaces) | SPI Controller used for SPI_DEV(1), can be `VSPI` `HSPI` | o
[SPI1_SCK](#esp32_spi_interfaces) | GPIO used as SCK for SPI_DEV(1) | o
[SPI1_MOSI](#esp32_spi_interfaces) | GPIO used as MOSI for SPI_DEV(1) | o
[SPI1_MISO](#esp32_spi_interfaces) | GPIO used as MISO for SPI_DEV(1) | o
[SPI1_CS0](#esp32_spi_interfaces) | GPIO used as default CS for SPI_DEV(1) | o
[UART1_TXD](#esp32_uart_interfaces) | GPIO used as TxD for UART_DEV(1) | o
[UART1_RXD](#esp32_uart_interfaces) | GPIO used as RxD for UART_DEV(1) | o
[UART2_TXD](#esp32_uart_interfaces) | GPIO used as TxD for UART_DEV(2) | o
[UART2_RXD](#esp32_uart_interfaces) | GPIO used as RxD for UART_DEV(2) | o
</center>
1. **Type**: m - mandatory, o - optional
The following table gives a short reference in alphabetical order of modules
that can be enabled/disabled by board configurations and/or application's
makefile using `USEMODULE` and `DISABLE_MODULE`.
<center>
Module | Default | Short description
----------------------------------------------------|-----------|-------------------
[esp_eth](#esp32_ethernet_network_interface) | not used | enable the Ethernet MAC (EMAC) network device
[esp_gdb](#esp32_debugging) | not used | enable the compilation with debug information for debugging
[esp_hw_counter](#esp32_timers) | not used | use hardware counters for RIOT timers
[esp_i2c_hw](#esp32_i2c_interfaces) | not used | use the i2C hardware implementation
[esp_idf_heap](#esp32_esp_idf_heap_implementation) | not used | enable ESP-IDF heap implementation
[esp_log_colored](#esp32_esp_log_module) | not used | enable colored log output
[esp_log_startup](#esp32_esp_log_module) | not used | enable additional startup information
[esp_log_tagged](#esp32_esp_log_module) | not used | add additional information to the log output
[esp_now](#esp32_esp_now_network_interface) | not used | enable the ESP-NOW network device
[esp_qemu](#esp32_esp_qemu) | not used | build QEMU for ESP32 application image
[esp_rtc_timer_32k](#esp32_rtt_counter) | not used | use RTC timer with external 32.768 kHz crystal as RTT
[esp_spi_ram](#esp32_spi_ram) | not used | enable SPI RAM
[esp_spiffs](#esp32_spiffs_device) | not used | enable SPIFFS for on-board flash memory
[esp_wifi](#esp32_wifi_network_interface) | not used | enable the Wifi network device in WPA2 personal mode
[esp_wifi_ap](#esp32_wifi_ap_network_interface) | not used | enable the WiFi SoftAP network device
[esp_wifi_enterprise](#esp32_wifi_network_interface)| not used | enable the Wifi network device in WPA2 enterprise mode
</center>
[Back to table of contents](#esp32_toc)
# MCU ESP32 {#esp32_mcu_esp32}
ESP32 is a low-cost, ultra-low-power, single or dual-core SoCs from Espressif Systems with
integrated WiFi and dual-mode BT module. The processor core is based on the Tensilica Xtensa LX6
32-bit Controller Processor Core.
[Back to table of contents](#esp32_toc)
## Features of ESP32 {#esp32_features}
The key features of ESP32 are:
<center>
| MCU | ESP32 | Supported by RIOT |
| ------------------|-------------------------------------------------------------------|------------------ |
| Vendor | Espressif | |
| Cores | 1 or 2 x Tensilica Xtensa LX6 | 1 core |
| FPU | ULP - Ultra low power co-processor | no |
| RAM | 520 KiB SRAM <br> 8 KiB slow RTC SRAM <br> 8 KiB fast RTC SRAM | yes <br> yes <br> yes |
| ROM | 448 KiB | yes |
| Flash | 512 KiB ... 16 MiB | yes |
| Frequency | 240 MHz, 160 MHz, 80 MHz | yes |
| Power Consumption | 68 mA @ 240 MHz <br> 44 mA @ 160 MHz (34 mA @ 160 MHz single core) <br> 31 mA @ 80 MHz (25 mA @ 80 MHz single core) <br> 800 uA in light sleep mode <br> 10 uA in deep sleep mode | yes <br> yes <br> yes <br> yes <br> yes |
| Timers | 4 x 64 bit | yes |
| ADCs | 2 x SAR-ADC with up to 18 x 12 bit channels total | yes |
| DACs | 2 x DAC with 8 bit | yes |
| GPIOs | 34 (6 are only inputs, 18 are RTC GPIOs) | yes |
| I2Cs | 2 | yes |
| SPIs | 4 | yes (2) |
| UARTs | 3 | yes |
| WiFi | IEEE 802.11 b/g/n built in | yes |
| Bluetooth | v4.2 BR/EDR and BLE | no |
| Ethernet | MAC interface with dedicated DMA and IEEE 1588 support | yes |
| CAN | version 2.0 | yes |
| IR | up to 8 channels TX/RX | no |
| Motor PWM | 2 devices x 6 channels | yes |
| LED PWM | 16 channels | no |
| Crypto | Hardware acceleration of AES, SHA-2, RSA, ECC, RNG | no |
| Vcc | 2.5 - 3.6 V | |
| Documents | [Datasheet](https://www.espressif.com/sites/default/files/documentation/esp32_datasheet_en.pdf) <br> [Technical Reference](https://www.espressif.com/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf) | |
</center><br>
@note Even if used ESP32 SoC is a dual-core version, RIOT-OS uses only one core.
Rather than using the ESP32 SoC directly, ESP32 boards use an
[ESP32 module from Espressif](https://www.espressif.com/en/products/hardware/modules) which
integrates additionally to the SoC some key components, like SPI flash memory, SPI RAM, or crystal
oscillator. Some of these components are optional. A good overview about available modules can be
found in the [Online documentation of ESP-IDF](https://www.espressif.com/en/products/modules).
Most common modules used by ESP32 boards are the
[ESP32-WROOM-32](https://www.espressif.com/sites/default/files/documentation/esp32-wroom-32_datasheet_en.pdf)
and
[ESP32-WROVER](https://www.espressif.com/sites/default/files/documentation/esp32-wrover_datasheet_en.pdf).
[Back to table of contents](#esp32_toc)
## Features Supported by RIOT-OS {#esp32_supported_features}
The RIOT-OS for ESP32 SoCs supports the following features at the moment:
- I2C interfaces
- SPI interfaces
- UART interfaces
- CAN interface
- CPU ID access
- RTC module
- ADC and DAC channels
- PWM channels
- SPI RAM
- SPI Flash Drive (MTD with SPIFFS and VFS)
- Layered Power Management
- Hardware number generator
- Hardware timer devices
- ESP-NOW netdev interface
- ESP Ethernet MAC (EMAC) netdev interface
[Back to table of contents](#esp32_toc)
## Limitations of the RIOT port {#esp32_limitations}
The implementation of RIOT-OS for ESP32 SOCs has the following limitations at the moment:
- Only **one core** (the PRO CPU) is used because RIOT does not support running multiple threads
simultaneously.
- **Bluetooth** cannot be used at the moment.
- **Flash encryption** is not yet supported.
[Back to table of contents](#esp32_toc)
# Toolchain {#esp32_toolchain}
To build RIOT applications for ESP32, the following components are required:
- ESP32 Toolchain including GCC, GDB and optionally OpenOCD and QEMU
- ESP32 SDK called ESP-IDF (Espressif IoT Development Framework)
- `esptool.py` for flashing
Principally, there are two ways to install and use the ESP32 toolchain, either
- using the **RIOT Docker build image**, see section
[Using RIOT Docker Toolchain](#esp32_riot_docker_toolchain), or
- using a **local installation** of the ESP32 toolchain, see section
[Using Local Toolchain Installation](#esp32_local_toolchain_installation).
[Back to table of contents](#esp32_toc)
## Using RIOT Docker Toolchain {#esp32_riot_docker_toolchain}
The easiest way to use the ESP32 toolchain is to use the RIOT Docker build
image. It is specially prepared for building RIOT applications for various
platforms and already has all the required tools and packages installed.
Details on how to setup Docker can be found in section
[Getting Started](https://doc.riot-os.org/getting-started.html#docker).
The building process using Docker comprises two steps:
1. Building the RIOT application **in Docker** using command:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ sudo docker run --rm -i -t -u $UID -v $(pwd):/data/riotbuild riot/riotbuild
riotbuild@container-id:~$ make BOARD= ...
riotbuild@container_id:~$ exit
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2. Flashing the RIOT application **on the host system** using command
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ make flash-only BOARD=...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Both steps can also be performed with a single command on the host system
by setting the `BUILD_IN_DOCKER` variable:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ BUILD_IN_DOCKER=1 DOCKER="sudo docker" \
make flash BOARD=...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@note
During the migration phase from the ESP32 toolchain with GCC 5.2.0, which was
specially compiled for RIOT, to Espressif's precompiled ESP32 vendor toolchain
with GCC 8.4.0, the RIOT Docker build image
[schorcht/riotbuild_esp32_espressif_gcc_8.4.0]
(https://hub.docker.com/repository/docker/schorcht/riotbuild_esp32_espressif_gcc_8.4.0)
has to be used instead of `riot/riotbuild` as this already contains the
precompiled ESP32 vendor toolchain from Espressif while `riot/riotbuild`
does not.
Therefore, the RIOT Docker build image has to be pulled with command:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ sudo docker pull schorcht/riotbuild_esp32_espressif_gcc_8.4.0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
and the RIOT Docker build image in step 1 has to be started with command:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ sudo docker run --rm -i -t -u $UID -v $(pwd):/data/riotbuild schorcht/riotbuild_esp32_espressif_gcc_8.4.0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The single step build command on the host system has then to be:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ BUILD_IN_DOCKER=1 DOCKER="sudo docker" DOCKER_IMAGE=schorcht/riotbuild_esp32_espressif_gcc_8.4.0 \
make flash BOARD=...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[Back to table of contents](#esp32_toc)
## Using Local Toolchain Installation {#esp32_local_toolchain_installation}
### Prerequisites
In addition to the common tools defined in section
[Getting Started - Common Tools](https://doc.riot-os.org/getting-started.html#compiling-riot),
the following tools or packages are required to install and use the ESP32
toolchain (Debian/Ubuntu package names):
- `curl`
- `python3`
- `python3-serial`
- `telnet`
### Script-based installation
The shell script `$RIOTBASE/dist/tools/esptools/install.sh` is used to
install Espressif's precompiled versions of the following tools:
- ESP32 vendor toolchain
- OpenOCD for ESP32
- QEMU for ESP32
`$RIOTBASE` defines the root directory of the RIOT repository. The shell
script takes an argument that specifies which tools to download and install:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ dist/tools/esptools/install.sh
install.sh <tool>
tool = all | esp32 | openocd | qemu
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Thus, either all tools or only certain tools can be installed.
The ESP32 tools are installed within a subdirectory of the directory specified
by the environment variable `$IDF_TOOLS_PATH`. If the environment variable
`$IDF_TOOLS_PATH` is not defined, `$HOME/.espressif` is used as default.
Using the variable `IDF_TOOLS_PATH` and its default value `$HOME/.espressif` for
the toolchain installation in RIOT allows to reuse the tools that have already
been installed according to the section ["Get Started, Step 3. Set up the tools"]
(https://docs.espressif.com/projects/esp-idf/en/latest/esp32/get-started/linux-macos-setup.html#get-started-set-up-tools).
if you have already used ESP-IDF directly.
### Using the toolchain
Once the ESP32 tools are installed in the directory specified by the
environment variable `$IDF_TOOLS_PATH`, the shell script
`$RIOTBASE/dist/tools/esptools/install.sh` can be sourced to export the
paths of the installed tools using again the environment variable
`$IDF_TOOLS_PATH`.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ . dist/tools/esptools/export.sh
Usage: export.sh <tool>
tool = all | esp32 | openocd | qemu
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
All the tools required for building a RIOT application for ESP32 should then
be found in the path.
[Back to table of contents](#esp32_toc)
### Installation of the ESP32 SDK (ESP-IDF) {#esp32_installation_of_esp_idf}
RIOT-OS uses the ESP-IDF, the official SDK from Espressif, as part of the
build. It is downloaded as a package at build-time and there is no need to
install it separately.
### Installation of esptool.py (ESP flash programmer tool) {#esp32_installation_of_esptool}
The RIOT port does not work with the `esptool.py` ESP flasher program
available on [GitHub](https://github.com/espressif/esptool) or
as a package for your OS. Instead, a modified version included in
ESP-IDF SDK is required.
To avoid the installation of the complete ESP-IDF SDK, for example, because
RIOT Docker build image is used for compilation, `esptool.py` has been
extracted from the SDK and placed in RIOT's directory `dist/tools/esptool`.
For convenience, the build system uses always the version from this directory.
Therefore, it is **not necessary to install** `esptool.py` explicitly. However
`esptool.py` depends on `pySerial` which can be installed either
using `pip`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ sudo pip3 install pyserial
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
or the package manager of your OS, for example on Debian/Ubuntu systems:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ apt install python3-serial
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For more information on `esptool.py`, please refer to the
[git repository](https://github.com/espressif/esptool).
[Back to table of contents](#esp32_toc)
# Flashing the Device {#esp32_flashing_the_device}
## Toolchain Usage {#esp32_toolchain_usage}
Once the toolchain is installed either as RIOT docker build image or as local installation, a RIOT application can be compiled and flashed for an ESP32 boards. For that purpuse change to RIOT's root directory and execute the make
command, for example:
- RIOT Docker build image installation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ BUILD_IN_DOCKER=1 DOCKER="sudo docker" \
make flash BOARD=esp32-wroom-32 -C tests/shell [Compile Options]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Local toolchain installation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ make flash BOARD=esp32-wroom-32 -C tests/shell [Compile Options]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The `BOARD` variable in the example specifies the generic ESP32 board
definition and option `-C` the directory of the application.
[Back to table of contents](#esp32_toc)
## Compile Options {#esp32_compile_options}
The compilation process can be controlled by a number of variables for the make command:
<center>
Option | Values | Default | Description
------------|-----------------------|---------------|------------
`CFLAGS` | string | empty | Override default board and driver configurations, see section [Application-Specific Configurations](#esp32_application_specific_configurations).
`FLASH_MODE`| dout, dio, qout, qio | dout | Set the flash mode, see section [Flash Modes](#esp32_flash_modes)
`PORT` | `/dev/tty*` | `/dev/ttyUSB0`| Set the port for flashing the firmware.
</center><br>
Optional features of ESP32 can be enabled by `USEMODULE` definitions in the makefile of the
application. These are:
<center>
Module | Description
--------------------|------------
esp_eth | Enable the Ethernet MAC (EMAC) interface as `netdev` network device, see section [Ethernet Network Interface](#esp32_ethernet_network_interface).
esp_gdb | Enable the compilation with debug information for debugging with [QEMU and GDB](#esp32_qemu_mode_and_gdb) (`QEMU=1`) or via [JTAG interface with OpenOCD](#esp32_jtag_debugging).
esp_i2c_hw | Use the hardware I2C implementation, see section [I2C Interfaces](#esp32_i2c_interfaces).
esp_idf_heap | Use the ESP-IDF heap implementation, see section [ESP-IDF Heap Implementation](#esp32_esp_idf_heap_implementation).
esp_log_colored | Enable colored log output, see section [Log output](#esp32_esp_log_module).
esp_log_startup | Enable additional startup information, see section [Log output](#esp32_esp_log_module).
esp_log_tagged | Add additional information to the log output, see section [Log output](#esp32_esp_log_module).
esp_now | Enable the built-in WiFi module with the ESP-NOW protocol as `netdev` network device, see section [ESP-NOW Network Interface](#esp32_esp_now_network_interface).
esp_qemu | Generate an application image for QEMU, see section [QEMU Mode and GDB](#esp32_qemu_mode_and_gdb).
esp_rtc_timer_32k | Enable RTC hardware timer with external 32.768 kHz crystal.
esp_spiffs | Enable the optional SPIFFS drive in on-board flash memory, see section [SPIFFS Device](#esp32_spiffs_device).
esp_spi_ram | Enable the optional SPI RAM, see section [SPI RAM Modules](#esp32_spi_ram).
esp_wifi | Enable the built-in WiFi module as `netdev` network device in WPA2 personal mode, see section [WiFi Network Interface](#esp32_wifi_network_interface).
esp_wifi_ap | Enable the built-in WiFi SoftAP module as `netdev` network device, see section [WiFi SoftAP Network Interface](#esp32_wifi_ap_network_interface).
esp_wifi_enterprise | Enable the built-in WiFi module as `netdev` network device in WPA2 enterprise mode, see section [WiFi Network Interface](#esp32_wifi_network_interface).
</center><br>
For example, to activate a SPIFFS drive in on-board flash memory, the makefile of application has
simply to add the `esp_spiffs` module to `USEMODULE` make variable:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += esp_spiffs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Modules can be also be activated temporarily at the command line when calling the make command:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE="esp_spiffs" make BOARD=...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[Back to table of contents](#esp32_toc)
## Flash Modes {#esp32_flash_modes}
The `FLASH_MODE` make command variable determines the mode that is used for flash access in
normal operation.
The flash mode determines whether 2 data lines (`dio` and `dout`) or 4 data lines
(`qio` and `qout`) for addressing and data access. For each data line, one GPIO is required.
Therefore, using `qio` or `qout` increases the performance of SPI Flash data transfers, but
uses two additional GPIOs (GPIO9 and GPIO10). That is, in this flash modes these GPIOs are not
available for other purposes. If you can live with lower flash data transfer rates, you should
always use `dio` or `dout` to keep GPIO9 and GPIO10 free for other purposes.
For more information about these flash modes, refer the documentation of
[esptool.py](https://github.com/espressif/esptool/wiki/SPI-Flash-Modes).
[Back to table of contents](#esp32_toc)
## Log output {#esp32_esp_log_module}
The RIOT port for ESP32 implements a log module with a bunch of macros
to generate log output according to the interface as defined in
\ref core_util_log "system logging header". These macros support colored and tagged log output.
The colored log output is enabled by module `esp_log_colored`. If colored log
output is enabled, log messages are displayed in color according to their type:
Error messages are displayed in red, warnings in yellow, information
messages in green and all other message types in standard color.
When the `esp_log_tagged` module is used, all log messages are tagged with
additional information: the type of message, the system time in ms, and the
module or function in which the log message is generated. For example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I (663) [main_trampoline] main(): This is RIOT! (Version: 2019.10-devel-437-gf506a)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Either the `LOG_*` macros as defined in
\ref core_util_log "system logging header" or the tagged
version `LOG_TAG_*` of these macros can be used to produce tagged log output.
If the `LOG_*` macros are used, the function which generates the log message
is used in the tag while a `tag` parameter is used for the `LOG_TAG_*` macros.
For example,
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
LOG_ERROR("error message");
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
generates a log message in which the name of the calling function is used as
tag. With
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
LOG_TAG_ERROR("mod", "error message");
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
a log message with string `mod` in the tag is generated.
The `esp_log_startup` module can be used to enable additional information
about the boot process, the board configuration, the system configuration,
the CPU used by the system, and the available heap. These information may
help to detect problems during the startup. If the application does not
start as expected, this module should be used.
[Back to table of contents](#esp32_toc)
## ESP-IDF Heap Implementation {#esp32_esp_idf_heap_implementation}
ESP-IDF SDK provides a complex heap implementation that supports multiple heap segments in different
memory areas such as DRAM, IRAM, and PSRAM. Whenever you want to use these memory areas as heap, you
have to use the heap implementation from the ESP-IDF SDK. ESP-IDF heap is not used by default.
To use it, it has to be enabled by the the makefile of the application:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += esp_heap
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@note
ESP-IDF heap implementation is used by default, when the following modules are used:
`esp_spi_ram`
[Back to table of contents](#esp32_toc)
# Common Peripherals {#esp32_peripherals}
ESP32 is an SoC and has a lot of peripherals that are not all supported by the RIOT port. This
section describes the supported peripherals and how they have to be configured.
[Back to table of contents](#esp32_toc)
## GPIO pins {#esp32_gpio_pins}
ESP32 has 34 GPIO pins, where only a subset can be used as output, as
ADC channel, as DAC channel and as GPIOs in deep-sleep mode, the so-called
RTC GPIOs. Some of them are used by special SoC components, e.g., as touch
sensors. The following table gives a short overview.
<center>
Pin | Type | ADC / RTC | PU / PD | Special function | Remarks
-------|:-------|:---------:|:---------:|-----------------------|--------
GPIO0 | In/Out | yes | yes | Touch sensor | Bootstrapping, pulled up
GPIO1 | In/Out | - | yes | UART0 TxD | Console
GPIO2 | In/Out | yes | yes | Touch sensor | Bootstrapping, pulled down
GPIO3 | In/Out | - | yes | UART0 RxD | Console
GPIO4 | In/Out | yes | yes | Touch sensor | -
GPIO5 | In/Out | - | yes | - | -
GPIO6 | In/Out | - | yes | Flash SD_CLK | -
GPIO7 | In/Out | - | yes | Flash SD_DATA0 | -
GPIO8 | In/Out | - | yes | Flash SD_DATA1 | -
GPIO9 | In/Out | - | yes | Flash SD_DATA2 | only in `qout`and `qio`mode, see section [Flash Modes](#esp32_flash_modes)
GPIO10 | In/Out | - | yes | Flash SD_DATA3 | only in `qout`and `qio`mode, see section [Flash Modes](#esp32_flash_modes)
GPIO11 | In/Out | - | yes | Flash SD_CMD | -
GPIO12 | In/Out | yes | yes | MTDI / Touch sensor | JTAG interface / Bootstrapping, pulled down
GPIO13 | In/Out | yes | yes | MTCK / Touch sensor | JTAG interface
GPIO14 | In/Out | yes | yes | MTMS / Touch sensor | JTAG interface
GPIO15 | In/Out | yes | yes | MTDO / Touch sensor | JTAG interface / Bootstrapping, pulled up
GPIO16 | In/Out | - | yes | - | usually not available when SPI RAM is used
GPIO17 | In/Out | - | yes | - | usually not available when SPI RAM is used
GPIO18 | In/Out | - | yes | - | -
GPIO19 | In/Out | - | yes | - | -
GPIO21 | In/Out | - | yes | - | -
GPIO22 | In/Out | - | yes | - | -
GPIO23 | In/Out | - | yes | - | -
GPIO25 | In/Out | yes | yes | DAC1 | -
GPIO26 | In/Out | yes | yes | DAC2 | -
GPIO27 | In/Out | yes | yes | Touch sensor | -
GPIO32 | In/Out | yes | yes | XTAL32_P | can be used to connect an external 32 kHz crystal
GPIO33 | In/Out | yes | - | XTAL32_N | can be used to connect an external 32 kHz crystal
GPIO34 | In | yes | - | VDET | -
GPIO35 | In | yes | - | VDET | -
GPIO36 | In | yes | - | SENSOR_VP | -
GPIO37 | In | yes | - | SENSOR_CAPP | usually not broken out
GPIO38 | In | yes | - | SENSOR_CAPN | usually not broken out
GPIO39 | In | yes | - | SENSOR_VN | -
</center>
<b>ADC:</b> these pins can be used as ADC inputs<br>
<b>RTC:</b> these pins are RTC GPIOs and can be used in deep-sleep mode<br>
<b>PU/PD:</b> these pins have software configurable pull-up/pull-down functionality.<br>
@note GPIOs that can be used as ADC channels are also available as low power digital inputs/outputs
in deep sleep mode.
GPIO0, GPIO2 are bootstrapping pins which are used to boot ESP32 in different modes:
<center>
GPIO0 | GPIO2 | Mode
:----:|:-----:|------------------
1 | X | boot in FLASH mode to boot the firmware from flash (default mode)
0 | 0 | boot in UART mode for flashing the firmware
</center><br>
@note GPIO2 becomes the SPI MISO signal for boards that use the HSPI interface as SD-Card interface
in 4-bit SD mode. On these boards all signals of the SD-Card interface are pulled up. Because
of the bootstrapping functionality of GPIO2, it can become necessary to either press the
**Boot** button, remove the SD card or remove the peripheral hardware to flash RIOT.
[Back to table of contents](#esp32_toc)
## ADC Channels {#esp32_adc_channels}
ESP32 integrates two 12-bit ADCs (ADC1 and ADC2) capable of measuring up to 18 analog signals in
total. Most of these ADC channels are either connected to a number of integrated sensors like a
Hall sensors, touch sensors and a temperature sensor or can be connected with certain GPIOs.
Integrated sensors are disabled in RIOT's implementation and are not accessible. Thus, up to 18
GPIOs, can be used as ADC inputs:
- **ADC1** supports 8 channels: GPIOs 32-39
- **ADC2** supports 10 channels: GPIOs 0, 2, 4, 12-15, 25-27
These GPIOs are realized by the RTC unit and are therefore also called RTC GPIOs or RTCIO GPIOs.
@note
- GPIO37 and GPIO38 are usually not broken out on ESP32 boards and can not be
used therefore.
- ADC2 is used by the WiFi module. The GPIOs connected to ADC2 are therefore not
available as ADC channels if the modules `esp_wifi` or `esp_now` are used.
The GPIOs that can be used as ADC channels for a given board are defined by the `#ADC_GPIOS`
macro in the board-specific peripheral configuration. This configuration can be changed by
[application-specific configurations](#esp32_application_specific_configurations).
Example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#define ADC_GPIOS { GPIO0, GPIO2, GPIO4 }
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The order of the listed GPIOs determines the mapping between the RIOT's ADC lines and the GPIOs. The
maximum number of GPIOs in the list is `#ADC_NUMOF_MAX` which is defined to be 16.
`#ADC_NUMOF` is determined automatically from `#ADC_GPIOS` list and must not be changed.
@note
- `#ADC_GPIOS` must be defined even if there are no GPIOs that could be used as ADC channels on
the board. In this case, an empty list hast to be defined which just contains the curly braces.
- As long as the GPIOs listed in ADC_GPIOS are not initialized as ADC channels with the
`#adc_init` function, they can be used for other purposes.
For each ADC line, an attenuation of the input signal can be defined separately with the
`#adc_set_attenuation` function.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
extern int adc_set_attenuation(adc_t line, adc_attenuation_t atten);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This results in different full ranges of the measurable voltage at the input. The attenuation can
be set to 0 dB, 3 dB, 6 dB and 11 dB, with 11 dB being the standard attenuation. Since an ADC input
is measured against a reference voltage Vref of 1.1 V, approximately the following measurement
ranges are given when using a corresponding attenuation:
<center>
Attenuation | Voltage Range | Symbol
----------------|-------------------|----------------------
0 dB | 0 ... 1.1V (Vref) | ADC_ATTENUATION_0_DB
3 dB | 0 ... 1.5V | ADC_ATTENUATION_3_DB
6 dB | 0 ... 2.2V | ADC_ATTENUATION_6_DB
11 dB (default) | 0 ... 3.3V | ADC_ATTENUATION_11_DB
</center><br>
@note The reference voltage Vref can vary from device to device in the range of 1.0V and 1.2V. The
Vref of a device can be read with the `#adc_vref_to_gpio25` function at GPIO 25.<br>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
extern int adc_vref_to_gpio25 (void);
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For that purpose GPIO25 is initialized automatically as ADC channel and is connected internally to
Vref to measure the current voltage. Once the initialization is finished and the function returns
with success, the current voltage can be read from GPIO25. The results of the ADC input can then be
adjusted accordingly. The `#adc_vref_to_gpio25` function can be used to determine the current
voltage at ESP32.
[Back to table of contents](#esp32_toc)
## DAC Channels {#esp32_dac_channels}
ESP32 supports 2 DAC lines at GPIO25 and GPIO26. These DACs have a width of 8 bits and produce
voltages in the range from 0 V to 3.3 V (VDD_A). The 16 bits DAC values given as parameter of
function `#dac_set` are down-scaled to 8 bit.
The GPIOs that can be used as DAC channels for a given board are defined by the `#DAC_GPIOS`
macro in the board-specific peripheral configuration. This configuration can be changed by
[application-specific configurations](#esp32_application_specific_configurations).
Example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#define DAC_GPIOS { GPIO25, GPIO26 }
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The order of the listed GPIOs determines the mapping between the RIOT's DAC lines and the GPIOs. The
maximum number of GPIOs in the list is `#DAC_NUMOF_MAX` which is defined to be 16.
`#DAC_NUMOF` is determined automatically from `#DAC_GPIOS` list and must not be changed.
@note
- `#DAC_GPIOS` must be defined even if there are no GPIOs that could be used as DAC channels on
the board. In this case, an empty list hast to be defined which just contains the curly braces.
- As long as the GPIOs listed in `#DAC_GPIOS` are not initialized as DAC channels with the
`#dac_init` function, they can be used for other purposes.
[Back to table of contents](#esp32_toc)
## I2C Interfaces {#esp32_i2c_interfaces}
The ESP32 has two built-in I2C hardware interfaces that support I2C bus speed up to 400 kbps
(`I2C_SPEED_FAST`).
The board-specific configuration of the I2C interface `I2C_DEV(n)` requires the definition of
- `I2Cn_SPEED`, the bus speed,
- `I2Cn_SCL`, the GPIO used as SCL signal, and
- `I2Cn_SDA`, the GPIO used as SDA signal,
where `n` can be 0 or 1. If they are not defined, the I2C interface `I2C_DEV(n)` is not used.
Example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#define I2C0_SPEED I2C_SPEED_FAST
#define I2C0_SCL GPIO22
#define I2C0_SDA GPIO21
#define I2C1_SPEED I2C_SPEED_NORMAL
#define I2C1_SCL GPIO13
#define I2C1_SDA GPIO16
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@note The configuration of the I2C interfaces `I2C_DEV(n)` must be in continuous ascending order
of n.
`#I2C_NUMOF` is determined automatically from board-specific peripheral definitions of
`I2Cn_SPEED`, `I2Cn_SCK`, and `I2Cn_SDA`.
The following table shows the default configuration of I2C interfaces used for a large number of
boards. It can be changed by
[application-specific configurations](#esp32_application_specific_configurations).
<center>
Device |Signal|Pin |Symbol |Remarks
:---------------|:-----|:-------|:------------|:----------------
I2C_DEV(0) | SCL | GPIO22 | `#I2C0_SCL` | -
I2C_DEV(0) | SDA | GPIO21 | `#I2C0_SDA` | -
</center><br>
@note The GPIOs listed in the configuration are only initialized as I2C signals when the
`periph_i2c` module is used. Otherwise they are not allocated and can be used for other
purposes.
Beside the I2C hardware implementation, a I2C bit-banging protocol software implementation can be
used. This implementation allows bus speeds up to 1 Mbps (`#I2C_SPEED_FAST_PLUS`). It can be
activated by adding
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += esp_i2c_sw
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
to application's makefile. The Disadvantage of the software implementation is that it uses busy
waiting.
@note The hardware implementation seems to be very poor and faulty. I2C commands in the I2C command
pipeline are sporadically not executed. A number of ACK errors and timeouts caused by protocol
errors are the result. The hardware implementation is recommended only if they can be
tolerated. Therefore, the software implementation is used by default.
[Back to table of contents](#esp32_toc)
## PWM Channels {#esp32_pwm_channels}
ESP supports two types of PWM generators
- one LED PWM controller (LEDPWM) with 16 channels, and
- two high-speed Motor Control PWM controllers (MCPWM) with 6 channels each.
The PWM implementation uses the ESP32's high-speed MCPWM modules. Reason is that the LED PWM
controller only supports resolutions of powers of two.
ESP32 has 2 MCPWM modules, each with up to 6 channels (`PWM_CHANNEL_NUM_DEV_MAX`). Thus, the
maximum number of PWM devices is 2 and the maximum total number of PWM channels is 12. These 2 MCPWM
devices are used as RIOT PWM devices `#PWM_DEV(0)` and `#PWM_DEV(1)`.
The GPIOs that can be used as PWM channels of RIOT's PWM devices are defined by the
`#PWM0_GPIOS` and `PWM1_GPIOS` macros in the board-specific peripheral configuration.
This configuration can be changed by
[application specific configurations](#esp32_application_specific_configurations).
Example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#define PWM0_GPIOS { GPIO9, GPIO10 }
#define PWM1_GPIOS { }
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The order of the listed GPIOs determines the mapping between RIOT's PWM channels and the GPIOs.
Board definitions usually declare a number of GPIOs as PWM channels.
@note The definition of `#PWM0_GPIOS` and `PWM1_GPIOS` can be omitted or empty. In the latter
case, they must at least contain the curly braces. The corresponding PWM device can not be
used in this case.
`#PWM_NUMOF` is determined automatically from the `#PWM0_GPIOS` and `PWM1_GPIOS` definitions and
must not be changed.
@note As long as the GPIOs listed in `#PWM0_GPIOS` and `PMW1_GPIOS` are not initialized as
PWM channels with the `#pwm_init` function, they are not allocated and can be used other
purposes.
[Back to table of contents](#esp32_toc)
## SPI Interfaces {#esp32_spi_interfaces}
ESP32 integrates four SPI controllers:
- controller SPI0 is reserved for caching the flash memory
- controller SPI1 is reserved for interface `FSPI` to external memories like flash and PSRAM
- controller SPI2 realizes interface `HSPI` that can be used for peripherals
- controller SPI3 realizes interface `VSPI` that can be used for peripherals
Thus, a maximum of two SPI controllers can be used as peripheral interfaces:
- `VSPI`
- `HSPI`
All SPI interfaces could be used in quad SPI mode, but RIOT's low level device driver doesn't
support it.
The board-specific configuration of the SPI interface `SPI_DEV(n)` requires the definition of
- `SPIn_CTRL`, the SPI controller which is used for `SPI_DEV(n)`, can be `VSPI` or
`HSPI`,
- `SPIn_SCK`, the GPIO used as clock signal for `SPI_DEV(n)`,
- `SPIn_MISO`, the GPIO used as MISO signal for `SPI_DEV(n)`,
- `SPIn_MOSI`, the GPIO used as MOSI signal for `SPI_DEV(n)`, and
- `SPIn_CS0`, the GPIO used as CS signal for `SPI_DEV(n)` when the cs parameter in
spi_acquire is `#GPIO_UNDEF`,
where `n` can be 0 or 1. If they are not defined, the SPI interface `SPI_DEV(n)` is not
used.
Example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#define SPI0_CTRL VSPI
#define SPI0_SCK GPIO18 // SCK Periphery
#define SPI0_MISO GPIO19 // MISO Periphery
#define SPI0_MOSI GPIO23 // MOSI Periphery
#define SPI0_CS0 GPIO5 // CS0 Periphery
#define SPI1_CTRL HSPI
#define SPI1_SCK GPIO14 // SCK Camera
#define SPI1_MISO GPIO12 // MISO Camera
#define SPI1_MOSI GPIO13 // MOSI Camera
#define SPI1_CS0 GPIO15 // CS0 Camera
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The pin configuration of `VSPI` interface and the `HSPI` interface can be changed by
[application specific configurations](#esp32_application_specific_configurations).
@note
- The configuration of the SPI interfaces `SPI_DEV(n)` should be in
continuous ascending order of `n`.
- The order in which the interfaces `VSPI` and `HSPI` are used doesn't
matter. For example, while one board may only use the `HSPI` interface as
`#SPI_DEV(0)`, another board may use the `VSPI` interface as
`#SPI_DEV(0)` and the `HSPI` interface as `SPI_DEV(1)`.
- The GPIOs listed in the configuration are first initialized as SPI signals
when the corresponding SPI interface is used by calling either the
`#spi_init_cs` function or the `#spi_acquire` function. That is, they
are not allocated as SPI signals before and can be used for other purposes as
long as the SPI interface is not used.
- GPIO2 becomes the MISO signal in SPI mode on boards that use the HSPI as the
SD card interface in 4-bit SD mode. Because of the bootstrapping
functionality of the GPIO2, it can be necessary to either press the **Boot**
button, remove the SD card or remove the peripheral hardware to flash RIOT.
`#SPI_NUMOF` is determined automatically from the board-specific
peripheral definitions of `SPI_DEV(n)`.
The following table shows the pin configuration used for most boards, even
though it **can vary** from board to board.
<center>
Device|Signal|Pin |Symbol | Remarks
:-----|:----:|:-------|:-----------:|:---------------------------
VSPI | SCK | GPIO18 |`#SPI0_SCK` | can be used for peripherals
VSPI | MISO | GPIO19 |`#SPI0_MISO` | can be used for peripherals
VSPI | MOSI | GPIO23 |`#SPI0_MOSI` | can be used for peripherals
VSPI | CS0 | GPIO18 |`#SPI0_CS0` | can be used for peripherals
HSPI | SCK | GPIO14 |`#SPI1_SCK` | can be used for peripherals
HSPI | MISO | GPIO12 |`#SPI1_MISO` | can be used for peripherals
HSPI | MOSI | GPIO13 |`#SPI1_MOSI` | can be used for peripherals
HSPI | CS0 | GPIO15 |`#SPI1_CS0` | can be used for peripherals
FSPI | SCK | GPIO6 |- | reserved for flash and PSRAM
FSPI | CMD | GPIO11 |- | reserved for flash and PSRAM
FSPI | SD0 | GPIO7 |- | reserved for flash and PSRAM
FSPI | SD1 | GPIO8 |- | reserved for flash and PSRAM
FSPI | SD2 | GPIO9 |- | reserved for flash and PSRAM (only in `qio` or `qout` mode)
FSPI | SD3 | GPIO10 |- | reserved for flash and PSRAM (only in `qio` or `qout` mode)
</center><br>
Some boards use the HSPI as SD-Card interface (SDIO) in 4-bit SD mode.
<center>
Device|Pin | SD 4-bit mode | SPI mode
:-----|:------:|:-------------:|:----------:
HSPI | GPIO14 | CLK | SCK
HSPI | GPIO15 | CMD | CS0
HSPI | GPIO2 | DAT0 | MISO
HSPI | GPIO4 | DAT1 | -
HSPI | GPIO12 | DAT2 | -
HSPI | GPIO13 | DAT3 | MOSI
</center><br>
On these boards, all these signals are pulled up. This may cause flashing
problems due to the bootstrap function of the GPIO2 pin, see section
[GPIO pins](#esp32_gpio_pins).
[Back to table of contents](#esp32_toc)
## Timers {#esp32_timers}
There are two different implementations for hardware timers.
- **Timer Module implementation** It provides 4 high-speed timers, where 1 timer
is used for system time. The remaining **3 timer devices** with **1 channel**
each can be used as RIOT timer devices with a clock rate of 1 MHz.
- **Counter implementation** It uses CCOUNT/CCOMPARE registers to implement **2
timer devices** with **1 channel** each and a clock rate of 1 MHz.
By default, the hardware timer module is used. To use the hardware counter
implementation, add
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += esp_hw_counter
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
to application's makefile.
Timers are MCU built-in features and not board-specific. There is nothing to be configured.
[Back to table of contents](#esp32_toc)
## RTT implementation {#esp32_rtt_counter}
The RTT peripheral low-level driver provides a RTT (Real Time Timer) with
a frequency of 32.768 kHz. It either uses the RTC hardware timer if an
external 32.768 kHz crystal is connected to the ESP32 or the PLL-controlled
64-bit microsecond system timer to emulate the RTC timer.
Whether an external 32.768 kHz crystal is connected to the ESP32 is
specified as a feature by the board definition using the pseudomodule
`esp_rtc_timer_32k`. If the feature `esp_rtc_timer_32k` is defined but the
external 32.768 kHz crystal is not recognized during startup, the
PLL controlled 64 bit microsecond system timer is used to emulate the
RTC timer.
The RTT is retained during light and deep sleep as well as during a restart.
The RTC hardware timer is used for this purpose, regardless of whether an
external 32.768 kHz crystal is connected to the ESP32 or the internal 150 kHz
RC oscillator is used. All current timer values are saved in the RTC memory
before entering a sleep mode or restart and are restored after when waking up
or restarting.
@note The RTT implementation is also used to implement a RTC (Real Time Clock)
peripheral. For this purpose the module `rt_rtc` is automatically enabled
when the feature `periph_rtc` is used.
[Back to table of contents](#esp32_toc)
## UART Interfaces {#esp32_uart_interfaces}
ESP32 supports up to three UART devices. `#UART_DEV(0)` has a fixed pin
configuration and is always available. All ESP32 boards use it as standard
configuration for the console.
The pin configuration of `#UART_DEV(1)` and `#UART_DEV(2)` are defined in board specific peripheral configuration by
- `UARTn_TXD`, the GPIO used as TxD signal, and
- `UARTn_RXD`, the GPIO used as RxD signal,
where `n` can be 2 or 3. If they are not defined, the UART interface UART_DEV(n) is not used.
#UART_NUMOF is determined automatically from the board-specific
peripheral definitions of `UARTn_TXD` and `UARTn_RXD` and must not be
changed.
The following default pin configuration of UART interfaces as used by a most
boards can be overridden by the application, see section [Application-Specific
Configurations](#esp32_application_specific_configurations).
Device |Signal|Pin |Symbol |Remarks
:-----------|:-----|:-------|:-----------|:----------------
UART_DEV(0) | TxD | GPIO1 |`#UART0_TXD`| cannot be changed
UART_DEV(0) | RxD | GPIO3 |`#UART0_RXD`| cannot be changed
UART_DEV(1) | TxD | GPIO10 |`#UART1_TXD`| optional, can be overridden
UART_DEV(1) | RxD | GPIO9 |`#UART1_RXD`| optional, can be overridden
UART_DEV(2) | TxD | GPIO17 |`UART2_TXD` | optional, can be overridden
UART_DEV(2) | RxD | GPIO16 |`UART2_RXD` | optional, can be overridden
Example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#define UART1_TXD GPIO10 // UART_DEV(1) TxD
#define UART1_RXD GPIO9 // UART_DEV(1) RxD
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[Back to table of contents](#esp32_toc)
## CAN Interfaces {#esp32_can_interfaces}
The ESP32 intregates a CAN controller which is compatible with the NXP SJA1000
CAN controller. Thus, it is CAN 2.0B specification compliant and supports two
message formats:
- Base Frame Format (11-bit ID)
- Extended Frame Format (29-bit ID)
@note
- ESP32 CAN does not support CAN-FD and is not CAN-FD tolerant.
- ESP32 CAN does not support SJA1000's sleep mode and wake-up functionality.
As with the SJA1000, the ESP32 CAN controller provides only the data link layer
and the physical layer signaling sublayer. Therefore, depending on physical
layer requirements, an external transceiver module is required which converts
the `CAN-RX` and `CAN-TX` signals of the ESP32 into `CAN_H` and `CAN_L` bus
signals, e.g., the MCP2551 or SN65HVD23X transceiver for compatibility with
ISO 11898-2.
If module `periph_can` is used, the low-level CAN driver for the
ESP32 CAN controller is enabled. It provides a CAN DLL device that can be
used with RIOT's CAN protocol stack. It uses the ESP32 CAN controller
in SJA1000 PeliCAN mode. Please refer the
[SJA1000 Datasheet](https://www.nxp.com/documents/data_sheet/SJA1000.pdf)
for detailed information about the CAN controller and its programming.
The pin configuration of the CAN transceiver interface is usually defined
in board specific peripheral configuration by
- `#CAN_TX`, the GPIO used as TX transceiver signal, and
- `#CAN_RX`, the GPIO used as RX transceiver signal.
If the pin configuration is not defined, the following default configuration
is used which can be overridden by the application, see section
[Application-Specific Configurations](#esp32_application_specific_configurations).
Device |Signal|Pin |Symbol |Remarks
:-------|:-----|:-------|:--------------|:----------------
CAN | TX | GPIO5 |`CAN_TX` | optional, can be overridden
CAN | RX | GPIO35 |`CAN_RX` | optional, can be overridden
Example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#define CAN_TX GPIO10 // CAN TX transceiver signal
#define CAN_RX GPIO9 // CAN RX transceiver signal
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If the board has an external transceiver module connected to the ESP32 on-board,
module `periph_can` should be provided as feature in board's `Makefile.features`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FEATURES_PROVIDED += periph_can # CAN peripheral interface
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Otherwise, the application has to add the `periph_can` module in its makefile
when needed.
[Back to table of contents](#esp32_toc)
## Power Management {#esp32_power_management}
### Power Modes
The RIOT port for the ESP32 implements RIOT's layered power management. It
supports the following operating modes:
- The **Modem-sleep** mode is the default operating mode when the WiFi
interface is disabled.
- The **Active** mode is the default operating mode when the WiFi interface
is used by either the `esp-wifi` or `esp-now` module.
- In **Light-sleep** mode, the CPUs including peripherals are stalled, but
the SRAM is retained. The system can continue when it returns from this mode.
- In **Deep-sleep** the CPU and the SRAM are powered down. The RTC memory can
be retained. The system must be restarted when it returns from this mode.
Since the peripherals are not working during _Light-sleep_/_Deep-sleep_, the
CPU cannot be woken up by internal interrupt sources such as timers. Therefore,
RIOT's layered power management can't select them as idle power mode. They are
therefore blocked for normal operation. The application has to select them
explicitly using the `#pm_set` function. RIOT's layered power management
can only select either _Modem-sleep_ or _Active_ as the lowest unblocked mode.
But also in _Modem-sleep_ or _Active_ mode, the lowest possible power level
is used. For this purpose, the Xtensa ISA instruction `waiti` is used,
which saves power by setting the current interrupt level, turning off the
processor logic and waiting for an interrupt.
[Back to table of contents](#esp32_toc)
### Using Power Modes
_Modem-sleep_ mode and _Active_ mode are the default operating modes
dependent on whether the WiFi interface is used. They are selected
automatically by the system.
To enter the _Light-sleep_ or the _Deep-sleep_ mode, function `#pm_set` has
to be used with the according mode `ESP_PM_LIGHT_SLEEP` or `ESP_PM_DEEP_SLEEP`
as parameter. To exit from these modes, several wake-up sources can be used.
[Back to table of contents](#esp32_toc)
#### Wake-up Sources in _Light-sleep_ Mode
Possible wake-up sources for the _Light-sleep_ mode are:
- RTC timer (set the RTC timer alarm using `#rtc_set_alarm` before calling `#pm_set`)
- GPIOs that are configured as input with enabled interrupt
- RxD signal of UART0 and/or UART1 (configured with `ESP_PM_WUP_UART0` and
`ESP_PM_WUP_UART1`)
@note Since the digital core (MCU) is stalled during _Light-sleep_, it
is not possible to use timers like `periph_timer` or `ztimer` as wake-up source.
@warning
Since only level interrupts are supported in _Light-sleep_ mode,
defined edge interrupts of type `#GPIO_RISING` and `#GPIO_FALLING` are
implicitly mapped to `GPIO_HIGH` and `GPIO_LOW`, respectively, when
entering _Light-sleep_ mode.
[Back to table of contents](#esp32_toc)
#### Wake-up Sources in _Light-sleep_ Mode
Possible Wake-up sources for the _Deep-sleep_ mode are:
- RTC timer (set the RTC timer alarm using `#rtc_set_alarm` before calling `#pm_set`)
- RTC GPIOs (configured by `ESP_PM_WUP_PINS` and `ESP_PM_WUP_LEVEL`)
@note RTC GPIOs are the GPIOs that are realized by the RTC unit and can also
be used as ADC channels. See section [GPIO pins](#esp32_gpio_pins) and
[ADC Channels](#esp32_adc_channels) for more information.
[Back to table of contents](#esp32_toc)
### Configuration
Several definitions can be used during compile time to configure the
_Light-sleep_ and the _Deep-sleep_ mode:
<center>
Parameter | Default | Mode | Description
:----------------|:-------------------------|:------|:------------
ESP_PM_GPIO_HOLD | not defined | Deep | Hold GPIO output level if defined
ESP_PM_WUP_PINS | none | Deep | GPIOs used as wake-up source
ESP_PM_WUP_LEVEL | ESP_PM_WUP_PINS_ANY_HIGH | Deep | Level for wake-up pins to wake-up
ESP_PM_WUP_UART0 | disabled | Light | Positive UART0 RxD signal edges to wake-up
ESP_PM_WUP_UART1 | disabled | Light | Positive UART1 RxD signal edges to wake-up
</center><br>
@note
- If `ESP_PM_GPIO_HOLD` is defined, GPIOs hold their last output level
when entering _Deep-sleep_ mode. Please note that only RTC GPIOs
can hold their output value in _Deep-sleep_ mode.
- `ESP_PM_WUP_PINS` specifies either a single RTC GPIO or a comma separated
list of RTC GPIOs that are used as wake-up source in _Deep-sleep_ mode.
- `ESP_PM_WUP_LEVEL` specifies the level for the wake-up pins in _Deep-sleep_
mode:
- `ESP_PM_WUP_PINS_ANY_HIGH` (default) - The system is woken up when any of
the GPIOs specified in `ESP_PM_WUP_PINS` becomes HIGH.
- `ESP_PM_WUP_PINS_ALL_LOW` - The system is woken up when all GPIOs specified
in `ESP_PM_WUP_PINS` become LOW.
- `ESP_PM_WUP_UART0` and `ESP_PM_WUP_UART1` define the number of positive
edges of the RxD signal of the respective UART that are necessary to wake
up the system in the _Light-sleep_ mode. The value must be greater than 2,
otherwise UART is not activated as wake-up source. The specified value is
reduced by 2 so that `ESP_PM_WUP_UART0` or `ESP_PM_WUP_UART1` plus 2 is
the number of positive edges required to wake up.
In the following example the system shall be woken up from _Deep-sleep_ if
the pulled-up pin `GPIO25` (`ESP_PM_WUP_PINS=GPIO25`) goes LOW
(`ESP_PM_WUP_LEVEL=ESP_PM_WUP_PINS_ALL_LOW`). The last GPIO output values
are held (`ESP_PM_GPIO_HOLD`) in _Deep-sleep_ mode. From _Light-sleep_ the
system can be woken up by any of the GPIOs defined as input with enabled
interrupt or if the RxD signal of UART0 goes HIGH at least 4 times
(`ESP_PM_WUP_UART0=6`).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CFLAGS='-DESP_PM_WUP_PINS=GPIO25 -DESP_PM_WUP_LEVEL=ESP_PM_WUP_PINS_ALL_LOW \
-DESP_PM_WUP_UART0=6 -DESP_PM_GPIO_HOLD' \
make BOARD=esp32-wroom-32 -C tests/periph_pm
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[Back to table of contents](#esp32_toc)
### Saving Data in _Deep-sleep_ Mode
In _Deep-sleep_ mode the SRAM is powered down. However, the slow RTC memory
can be retained. Therefore, data that must be retained during _Deep-sleep_ and
the subsequent system restart, must be stored in the slow RTC memory. For
that purpose, use
- `__attribute__((section(".rtc.bss")))` to place uninitialized
data in section `.rtc.bss`, and
- `__attribute__((section(".rtc.data")))` to
place initialized data in section `.rtc.data`.
For example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
static int _i_value __attribute__((section(".rtc.bss"))); // set to 0 at power on
static int _u_value __attribute__((section(".rtc.data"))) = 1; // initialized
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[Back to table of contents](#esp32_toc)
## Other Peripherals {#esp32_other_peripherals}
The ESP32 port of RIOT also supports:
- hardware number generator with 32 bit
- CPU-ID function
- Vref measurement function
[Back to table of contents](#esp32_toc)
# Special On-board Peripherals {#esp32_special_on_board_peripherals}
## SPI RAM Modules {#esp32_spi_ram}
The ESP32 can use external SPI RAM connected through the FSPI interface. For example, all boards that use the [ESP32-WROVER modules](https://www.espressif.com/en/products/hardware/modules) have already integrated such SPI RAM.
However, the external SPI RAM requires 4 data lines and thus can only be used in QOUT (quad output) or QIO (quad input/output) flash mode, which makes GPIO9 and GPIO10 unavailable for other purposes. Therefore, if needed, the SPI RAM must be explicitly enabled in the makefile of the application.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += esp_spi_ram
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@note
- When the SPI RAM is enabled using the `esp_spi_ram`, the ESP32 uses four data lines to access the external SPI RAM in QOUT (quad output) flash mode. Therefore, GPIO9 and GPIO10 are used as SPI data lines and are not available for other purposes.
- Enabling SPI RAM for modules that don't have SPI RAM may lead to boot problems for some modules. For others is simply throws an error message.
[Back to table of contents](#esp32_toc)
## SPIFFS Device {#esp32_spiffs_device}
The RIOT port for ESP32 implements a MTD system drive `mtd0` using the on-board SPI flash memory. This MTD system drive can be used together with SPIFFS and VFS to realize a persistent file system.
To use the MTD system drive with SPIFFS, the `esp_spiffs` module has to be enabled in the makefile of the application:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += esp_spiffs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When SPIFFS is enabled, the MTD system drive is formatted with SPIFFS the first time the system is started. The start address of the MTD system drive in the SPI flash memory is defined by the board configuration:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#define SPI_FLASH_DRIVE_START 0x200000
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If this start address is set to 0, as in the default board configuration, the first possible multiple of 0x100000 (1 MiB) will be used in the free SPI flash memory determined from the partition table.
Please refer file `$RIOTBASE/tests/unittests/test-spiffs/tests-spiffs.c` for more information on how to use SPIFFS and VFS together with a MTD device `mtd0` alias `MTD_0`.
[Back to table of contents](#esp32_toc)
# Network Interfaces {#esp32_network_interfaces}
ESP32 provides different built-in possibilities to realize network devices:
- **EMAC**, an Ethernet MAC implementation (requires an external PHY module)
- **ESP WiFi**, usual AP-based wireless LAN
- **ESP-NOW**, a WiFi based AP-less and connectionless peer to peer communication protocol
- **ESP-MESH**, a WiFi based mesh technology (not yet supported)
[Back to table of contents](#esp32_toc)
## Ethernet MAC Network Interface {#esp32_ethernet_network_interface}
ESP32 provides an **Ethernet MAC layer module (EMAC)** according to the
IEEE 802.3 standard which can be used together with an external physical
layer chip (PHY) to realize a 100/10 Mbps Ethernet interface. Supported PHY
chips are the Microchip LAN8710/LAN8720, the IC Plus 101G, and the Texas
Instruments TLK110.
The RIOT port for ESP32 realizes with module `esp_eth` a `netdev` driver for
the EMAC which uses RIOT's standard Ethernet interface.
If the board has one of the supported PHY layer chips connected to the ESP32,
the `esp_eth` module should be enabled by default in board's `Makefile.dep`
when module `netdev_default` is used.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ifneq (,$(filter netdev_default,$(USEMODULE)))
USEMODULE += esp_eth
endif
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Otherwise, the application has to add the `esp_eth` module in its makefile when needed.
@note
The board has to have one of the supported PHY modules to be able to use the Ethernet MAC module.
[Back to table of contents](#esp32_toc)
## WiFi Network Interface {#esp32_wifi_network_interface}
The RIOT port for ESP32 implements a `netdev` driver for the built-in WiFi
interface. This `netdev` driver supports WPA2 personal mode as well as WPA2
enterprise mode.
[Back to table of contents](#esp32_toc)
### WPA2 personal mode
To use the WiFi `netdev` driver in WPA2 personal mode with a
preshared key (PSK), module `esp_wifi` has to be enabled.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += esp_wifi
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Furthermore, the following configuration parameters have to be defined:
<center>
Parameter | Default | Description
:-------------------|:--------------------------|:------------
#ESP_WIFI_SSID | "RIOT_AP" | SSID of the AP to be used.
#ESP_WIFI_PASS | - | Passphrase used for the AP as clear text (max. 64 chars).
#ESP_WIFI_STACKSIZE | #THREAD_STACKSIZE_DEFAULT | Stack size used for the WiFi netdev driver thread.
</center><br>
These configuration parameter definitions, as well as enabling the `esp_wifi`
module, can be done either in the makefile of the project or at make command
line, for example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE=esp_wifi \
CFLAGS='-DESP_WIFI_SSID=\"MySSID\" -DESP_WIFI_PASS=\"MyPassphrase\"' \
make -C examples/gnrc_networking BOARD=...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@note
- Module `esp_wifi` is not enabled automatically when module
`netdev_default` is used.
- Leave 'ESP_WIFI_PASS' undefined to connect to an open WiFi access point.
- The Wifi network interface (module `esp_wifi`) and the
[ESP-NOW network interface](#esp32_esp_now_network_interface) (module `esp_now`)
can be used simultaneously, for example, to realize a border router for
a mesh network which uses ESP-NOW.
[Back to table of contents](#esp32_toc)
### WPA2 Enterprise Mode
To use the WiFi `netdev` driver in WPA2 enterprise mode with IEEE 802.1X/EAP
authentication, module `esp_wifi_enterprise` has to be enabled.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += esp_wifi_enterprise
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It supports the following EAP authentication methods:
- PEAPv0
- PEAPv1
- TTLS
As inner (phase 2) EAP authentication method, only MSCHAPv2 is supported.
To use module `esp_wifi_enterprise` with these authentication methods, the
following configuration parameters have to be defined:
<center>
Parameter | Default | Description
:-------------------|:----------|:------------
#ESP_WIFI_SSID | "RIOT_AP" | SSID of the AP to be used.
ESP_WIFI_EAP_ID | none | Optional anonymous identity used in phase 1 (outer) EAP authentication.[1]
ESP_WIFI_EAP_USER | none | User name used in phase 2 (inner) EAP authentication.
ESP_WIFI_EAP_PASS | none | Password used in phase 2 (inner) EAP authentication.
#ESP_WIFI_STACKSIZE | #THREAD_STACKSIZE_DEFAULT | Stack size used for the WiFi netdev driver thread.
</center><br>
[1] If the optional anonymous identy `ESP_WIFI_EAP_ID` is not defined, the user
name `ESP_WIFI_EAP_USER` defined for phase 2 (inner) EAP authentication is used
as identity in phase 1.
These configuration parameter definitions, as well as enabling the `esp_wifi`
module, can be done either in the makefile of the project or at make command
line, for example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE=esp_wifi_enterprise \
CFLAGS='-DESP_WIFI_SSID=\"MySSID\" -DESP_WIFI_EAP_ID=\"anonymous\" -DESP_WIFI_EAP_USER=\"MyUserName\" -DESP_WIFI_EAP_PASS=\"MyPassphrase\"' \
make -C examples/gnrc_networking BOARD=...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@note
- Since there is no possibility to add the CA certificate to the RIOT image,
the verification of the AP certificate is not yet supported.
- Module `esp_wifi_enterprise` is not enabled automatically when module
`netdev_default` is used.
- The Wifi network interface (module `esp_wifi_enterprise`) and the
[ESP-NOW network interface](#esp32_esp_now_network_interface) (module `esp_now`)
can be used simultaneously, for example, to realize a border router for
a mesh network which uses ESP-NOW.
In this case the ESP-NOW interface must use the same channel as the AP of the
infrastructure WiFi network. All ESP-NOW nodes must therefore be compiled with
the channel of the AP as value for the parameter 'ESP_NOW_CHANNEL'.
[Back to table of contents](#esp32_toc)
## WiFi SoftAP Network Interface {#esp32_wifi_ap_network_interface}
The RIOT port for the ESP32 supports a `netdev` interface for the ESP32 WiFi
SoftAP mode. Module `esp_wifi_ap` has to be enabled to use it.
The following parameters can be configured:
<center>
Parameter | Default | Description
:-------------------------|:--------------------------|:-------------
#ESP_WIFI_SSID | "RIOT_AP" | Static SSID definition for the SoftAP
#ESP_WIFI_PASS | none | The password for the WiFi SoftAP network interface.[1]
#ESP_WIFI_SSID_DYNAMIC | 0 | Defines whether dynamic SSID is used for the SoftAP [2].
#ESP_WIFI_SSID_HIDDEN | 0 | Defines whether the SoftAP SSID should be hidden.
#ESP_WIFI_MAX_CONN | 4 | The maximum number of connections for the SoftAP.
#ESP_WIFI_BEACON_INTERVAL | 100 | The beacon interval time in milliseconds for the SoftAP.
#ESP_WIFI_STACKSIZE | #THREAD_STACKSIZE_DEFAULT | Stack size used for the WiFi netdev driver thread.
</center><br>
[1] If no password is provided, the interface will be "open", otherwise it
uses WPA2-PSK authentication mode.<br>
[2] If `#ESP_WIFI_SSID_DYNAMIC` is set to 1, a dynamic SSID is generated for the
SoftAP by extending the defined SSID (`ESP_WIFI_SSID`) with the MAC address
of the SoftAP interface used, e.g.: `RIOT_AP_aabbccddeeff`
These configuration parameter definitions, as well as enabling the `esp_wifi_ap`
module, can be done either in the makefile of the project or at make command
line, for example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE=esp_wifi_ap \
CFLAGS='-DESP_WIFI_SSID=\"MySSID\" -DESP_WIFI_PASS=\"MyPassphrase\" -DESP_WIFI_MAX_CONN=1' \
make -C examples/gnrc_networking BOARD=...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@note
- The `esp_wifi_ap` module is not used by default when `netdev_default` is used.
- Supports open and WPA2-PSK authentication modes.
- The ESP-NOW network interface and the WiFi SoftAP network interface can not
be used simultaneously.
@warning
The SoftAP may or may not be at all reliable sometimes, this is a known
problem with the Wi-Fi network interface, even on the official ESP-IDF.
The problem is that the AP doesn't cache multicast data for connected
stations, and if stations connected to the AP are power save enabled,
they may experience multicast packet loss. This affects RIOT, because
NDP relies on multicast packets to work correctly.
Refer to the SDK documentation from Espressif on
[AP Sleep](https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/wifi.html#ap-sleep)
for more information.
[Back to table of contents](#esp32_toc)
## ESP-NOW Network Interface {#esp32_esp_now_network_interface}
With ESP-NOW, the ESP32 provides a connectionless communication technology,
featuring short packet transmission. It applies the IEEE802.11 Action Vendor
frame technology, along with the IE function developed by Espressif, and CCMP
encryption technology, realizing a secure, connectionless communication
solution.
The RIOT port for ESP32 implements in module `esp_now` a `netdev`
driver which uses ESP-NOW to provide a link layer interface to a meshed network
of ESP32 nodes. In this network, each node can send short packets with up to
250 data bytes to all other nodes that are visible in its range.
@note Module `esp_now`module is not enabled automatically if the
`netdev_default` module is used. Instead, the application has to add the
`esp_now` module in its makefile when needed.<br>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += esp_now
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For ESP-NOW, ESP32 nodes are used in WiFi SoftAP + Station mode to advertise
their SSID and become visible to other ESP32 nodes. The SSID of an ESP32 node
is the concatenation of the prefix `RIOT_ESP_` with the MAC address of its
SoftAP WiFi interface. The driver periodically scans all visible ESP32 nodes.
The following parameters are defined for ESP-NOW nodes. These parameters can be overridden by
[application-specific board configurations](#esp32_application_specific_board_configuration).
<center>
Parameter | Default | Description
:-----------------------|:--------------------------|:-----------
ESP_NOW_SCAN_PERIOD_MS | 10000UL | Defines the period in ms at which an node scans for other nodes in its range. The default period is 10 s.
ESP_NOW_SOFT_AP_PASS | "ThisistheRIOTporttoESP" | Defines the passphrase as clear text (max. 64 chars) that is used for the SoftAP interface of ESP-NOW nodes. It has to be same for all nodes in one network.
ESP_NOW_CHANNEL | 6 | Defines the channel that is used as the broadcast medium by all nodes together.
ESP_NOW_KEY | NULL | Defines a key that is used for encrypted communication between nodes. If it is NULL, encryption is disabled. The key has to be of type `uint8_t[16]` and has to be exactly 16 bytes long.
</center><br>
@note The ESP-NOW network interface (module `esp_now`) and the
[Wifi network interface](#esp32_wifi_network_interface) (module `esp_wifi` or `esp_wifi_enterprise`)
can be used simultaneously, for example, to realize a border router for
a mesh network which uses ESP-NOW.
In this case the ESP-NOW interface must use the same channel as the AP of the
infrastructure WiFi network. All ESP-NOW nodes must therefore be compiled with
the channel of the AP asvalue for the parameter 'ESP_NOW_CHANNEL'.
[Back to table of contents](#esp32_toc)
## Other Network Devices {#esp32_other_network_devices}
RIOT provides a number of driver modules for different types of network
devices, e.g., IEEE 802.15.4 radio modules and Ethernet modules. The RIOT port
for ESP32 has been tested with the following network devices:
- \ref drivers_mrf24j40 "mrf24j40" (driver for Microchip MRF24j40 based IEEE 802.15.4)
- \ref drivers_enc28j60 "enc28j60" (driver for Microchip ENC28J60 based Ethernet modules)
[Back to table of contents](#esp32_toc)
### Using MRF24J40 (module mrf24j40) {#esp32_using_mrf24j40}
To use MRF24J40 based IEEE 802.15.4 modules as network device, the
`mrf24j40` driver module has to be added to the makefile of the
application:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += mrf24j40
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The driver parameters that have to be defined by the board configuration for
the MRF24J40 driver module are:
Parameter | Description
-----------------------|------------
MRF24J40_PARAM_CS | GPIO used as CS signal
MRF24J40_PARAM_INT | GPIO used as interrupt signal
MRF24J40_PARAM_RESET | GPIO used as reset signal
Since each board has different GPIO configurations, refer to the board
documentation for the GPIOs recommended for the MRF24J40.
@note The reset signal of the MRF24J40 based network device can be connected
with the ESP32 RESET/EN pin which is broken out on most boards. This keeps the
GPIO free defined by `MRF24J40_PARAM_RESET` free for other purposes.
[Back to table of contents](#esp32_toc)
### Using ENC28J60 (module enc28j60) {#esp32_using_enc28j60}
To use ENC28J60 Ethernet modules as network device, the `enc28j60` driver
module has to be added to the makefile of the application:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
USEMODULE += enc28j60
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The parameters that have to be defined by board configuration for the ENC28J60 driver module are:
Parameter | Description
---------------------|------------
ENC28J60_PARAM_CS | GPIO used as CS signal
ENC28J60_PARAM_INT | GPIO used as interrupt signal
ENC28J60_PARAM_RESET | GPIO used as reset signal
Since each board has different GPIO configurations, refer to the board
documentation for the GPIOs recommended for the ENC28J60.
@note The reset signal of the ENC28J60 based network device can be connected
with the ESP32 RESET/EN pin which is broken out on most boards. This keeps the
GPIO free defined by `#ENC28J60_PARAM_RESET` free for other purposes.
[Back to table of contents](#esp32_toc)
# Application-Specific Configurations {#esp32_application_specific_configurations}
The board-specific configuration files `board.h` and `periph_conf.h` as
well well as the driver parameter configuration files `<driver>_params.h`
define the default configurations for peripherals and device driver modules.
These are, for example, the GPIOs used, bus interfaces used or available bus
speeds. Because there are many possible configurations and many different
application requirements, these default configurations are usually only a
compromise between different requirements.
Therefore, it is often necessary to change some of these default configurations
for individual applications. For example, while many PWM channels are needed in
one application, another application does not need PWM channels, but many ADC
channels.
There are two ways to give the application the ability to change some of these
default configurations:
- make variable `CFLAGS`
- application-specific board or driver configuration file
[Back to table of contents](#esp32_toc)
## Make Variable CFLAGS {#esp32_config_make_variable}
Using the `CFLAGS` make variable at the command line, board or driver parameter
definitions can be overridden.
Example:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CFLAGS='-DESP_LCD_PLUGGED_IN=1 -DLIS3DH_PARAM_INT2=GPIO4'
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When a larger number of board definitions needs be overridden, this approach
becomes impractical. In that case, an application-specific board configuration
file located in application directory can be used, see sections below.
[Back to table of contents](#esp32_toc)
## Application-Specific Board Configuration {#esp32_application_specific_board_configuration}
To override default board configurations, simply create an application-specific
board configuration file `$APPDIR/board.h` in the source directory
`$APPDIR` of the application and add the definitions to be overridden. To
force the preprocessor to include board's original `board.h` after that,
add the `include_next` preprocessor directive as the **last** line.
For example to override the default definition of the GPIOs that are used as
PWM channels, the application-specific board configuration file
`$APPDIR/board.h` could look like the following:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#ifdef CPU_ESP32
#define PWM0_CHANNEL_GPIOS { GPIO12, GPIO13, GPIO14, GPIO15 }
#endif
#include_next "board.h"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It is important to ensure that the application-specific board
configuration `$APPDIR/board.h` is included first. Insert the following
line as the **first** line to the application makefile `$APPDIR/Makefile`.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
INCLUDES += -I$(APPDIR)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@note To make such application-specific board configurations dependent on the
ESP32 MCU or a particular ESP32 board, you should always enclose these
definitions in the following constructs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#ifdef CPU_ESP32
...
#endif
#ifdef BOARD_ESP32_WROVER_KIT
...
#endif
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[Back to table of contents](#esp32_toc)
## Application-Specific Driver Configuration {#esp32_application_specific_driver_configuration}
Using the approach for overriding board configurations, the parameters of
drivers that are typically defined in
`drivers/<device>/include/<device>_params.h` can be overridden. For that
purpose just create an application-specific driver parameter file
`$APPDIR/<device>_params.h` in the source directory `$APPDIR` of the
application and add the definitions to be overridden. To force the preprocessor
to include driver's original `<device>_params.h` after that, add the
`include_next` preprocessor directive as the **last** line.
For example, to override a GPIO used for LIS3DH sensor, the
application-specific driver parameter file `$APPDIR/<device>_params.h`
could look like the following:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#ifdef CPU_ESP32
#define LIS3DH_PARAM_INT2 (GPIO_PIN(0, 4))
#endif
#include_next "lis3dh_params.h"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It is important to ensure that the application-specific driver parameter file
`$APPDIR/<device>_params.h` is included first. Insert the following line as
the *first* line to the application makefile `$APPDIR/Makefile`.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
INCLUDES += -I$(APPDIR)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
\note To make such application-specific board configurations dependent on the ESP32 MCU or a
particular ESP32 board, you should always enclose these definitions in
the following constructs:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.c}
#ifdef CPU_ESP32
...
#endif
#ifdef BOARD_ESP32_WROVER_KIT
...
#endif
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[Back to table of contents](#esp32_toc)
# Debugging {#esp32_debugging}
## JTAG Debugging {#esp32_jtag_debugging}
ESP32 provides a JTAG interface at GPIOs 12 ... 15 for On-Chip Debugging.
ESP32 Pin | JTAG Signal
:-------------|:-----------
CHIP_PU | TRST_N
GPIO15 (MTDO) | TDO
GPIO12 (MTDI) | TDI
GPIO13 (MTCK) | TCK
GPIO14 (MTMS) | TMS
GND | GND
This JTAG interface can be used with OpenOCD and GDB for On-Chip debugging
of your software on instruction level. When you compile your software with
debugging information (module `esp_gdb`) you can debug on source code
level as well.
@note
When debugging, the GPIOs used for the JTAG interface must not be used for
anything else.
Some boards like the \ref esp32_wrover_kit_toc "ESP-WROVER-KIT V3" or the
\ref esp32-ethernet-kit-v1_0 "ESP32-Ethernet-Kit " have a USB bridge with
JTAG interface on-board that can be directly used for JTAG debugging.
To use the JTAG debugging, the precompiled version of OpenOCD for ESP32 has to
be installed using the install script while being in RIOT's
root directory, see also section
[Using Local Toolchain Installation](#esp32_local_toolchain_installation).
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ dist/tools/esptools/install.sh openocd
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Before OpenOCD can be used, the `PATH` variable has to be set correctly
and the `OPENOCD` variable has to be exported using the following command.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ . dist/tools/esptools/export.sh openocd
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Once the `PATH` variable as well as the `OPENOCD` variable are set, the
debugging session can be started using either
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ PROGRAMMER=openocd USEMODULE=esp_jtag \
make debug BOARD=esp32-wrover-kit
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
if the board defines an OpenOCD board configuration file or using
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ PROGRAMMER=openocd USEMODULE=esp_jtag OPENOCD_CONFIG=board/esp-wroom-32.cfg \
make debug BOARD=esp32-wroom-32
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
if the board does not define an OpenOCD board configuration file.
@note
The board will be reset, but not flashed with this command. However, flashing
would be also possible with OpenOCD and the JTAG interface using command:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ PROGRAMMER=openocd USEMODULE=esp_jtag \
make flash BOARD=esp32-wrover-kit
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Detailed information on how to configure the JTAG interface of the ESP32
can be found in section JTAG Debugging in the [ESP-IDF Programming Guide]
(https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-guides/jtag-debugging/index.html).
[Back to table of contents](#esp32_wrover_kit_toc)
## QEMU Mode and GDB {#esp32_qemu_mode_and_gdb}
RIOT applications that do not require interaction with real hardware such as
GPIOs, I2C or SPI devices, WiFi interface, etc. can also be debugged using
QEMU for ESP32. For this purpose, either QEMU for ESP32 must be installed,
see section [Local Toolchain Installation](#esp32_local_toolchain_installation)
or the RIOT Docker build image has to be used in which QEMU for ESP32 is already
installed.
To use QEMU for ESP32, an application has to be built with `esp_qemu` module
enabled, for example with local toolchain installation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ USEMODULE=esp_qemu make flash BOARD=esp32-wroom-32 -C tests/shell
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
or with RIOT Docker build image
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ BUILD_IN_DOCKER=1 DOCKER="sudo docker" \
USEMODULE=esp_qemu make flash BOARD=esp32-wroom-32 -C tests/shell
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Instead of flashing the image to the target hardware, a binary image named
`qemu_flash_image.bin` is created in the target directory. In addition, two ROM
files `rom.bin` and `rom1.bin` are copied to the target directory. These
files can then be used with QEMU for ESP32 to debug the application in GDB
without having the hardware. The binary image `qemu_flash_image.bin`
represents a 4 MByte Flash image.
QEMU for ESP32 can then be started with command:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ qemu-system-xtensa \
-s -machine esp32 \
-drive file=tests/shell/bin/esp32-wroom-32/qemu_flash_image.bin,if=mtd,format=raw \
-serial tcp::5555,server,nowait
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
To interact with the application on the emulated ESP32 in QEMU, a second
terminal is required in which the `telnet` command is used to communicate
with the application on `localhost` using TCP port 5555:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ telnet localhost 5555
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
main(): This is RIOT! (Version: 2022.04)
test_shell.
> help
help
Command Description
---------------------------------------
bufsize Get the shell's buffer size
start_test starts a test
...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
To debug the application in QEMU for ESP32, another terminal is required:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ xtensa-esp32-elf-gdb tests/shell/bin/esp32-wroom-32/tests_shell.elf
GNU gdb (crosstool-NG crosstool-ng-1.22.0-80-g6c4433a5) 7.10
Copyright (C) 2015 Free Software Foundation, Inc.
...
Reading symbols from tests/shell/bin/esp32-wroom-32/tests_shell.elf...done.
(gdb) target remote :1234
Remote debugging using :1234
pm_set (mode=2) at cpu/esp32/periph/pm.c:117
117 return;
(gdb)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
QEMU for ESP32 can also be used in RIOT Docker build image. For that purpose
QEMU has to be started in the Docker container.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ sudo docker run --rm -i -t -u $UID -v $(pwd):/data/riotbuild riot/riotbuild
riotbuild@container-id:~$ USEMODULE=esp_qemu make flash BOARD=esp32-wroom-32 -C tests/shell
riotbuild@container-id:~$ qemu-system-xtensa \
-s -machine esp32 \
-drive file=tests/shell/bin/esp32-wroom-32/qemu_flash_image.bin,if=mtd,format=raw \
-serial tcp::5555,server,nowait
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In a second and a third terminal, you need to execute a shell in the same RIOT
Docker container where QEMU for ESP32 was started. The required container ID
`<container-id>` is shown in the prompt of the terminal in which QEMU for ESP32
was started.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ sudo docker docker exec -it <container-id> bash
riotbuild@container-id:~$telnet localhost 5555
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
main(): This is RIOT! (Version: 2022.04)
test_shell.
>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ sudo docker docker exec -it <container-id> bash
riotbuild@container-id:~$ xtensa-esp32-elf-gdb tests/shell/bin/esp32-wroom-32/tests_shell.elf
GNU gdb (crosstool-NG crosstool-ng-1.22.0-80-g6c4433a5) 7.10
Copyright (C) 2015 Free Software Foundation, Inc.
...
Reading symbols from tests/shell/bin/esp32-wroom-32/tests_shell.elf...done.
(gdb) target remote :1234
Remote debugging using :1234
pm_set (mode=2) at cpu/esp32/periph/pm.c:117
117 return;
(gdb)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
[Back to table of contents](#esp32_toc)
*/
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