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169 lines
6.9 KiB
Plaintext
169 lines
6.9 KiB
Plaintext
/**
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@defgroup boards_rpi_pico Raspberry Pi Pico
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@ingroup boards
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@brief Support for the RP2040 based Raspberry Pi Pico board
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## Overview
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The Raspberry Pi Pico is sold by the Raspberry Pi foundation for about 4 USD. It features the
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RP2040 MCU, a custom dual core ARM Cortex-M0+ MCU with relatively high CPU clock, plenty of RAM and
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some unique peripheral (the Programmable IO).
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## Hardware
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### MCU
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The Programmable IO (PIO) peripheral and the SSI/QSPI peripheral that supports execution from
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flash (XIP) are the most distinguishing features of the MCU. The latter is especially important,
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since the RP2040 contains no internal flash.
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| MCU | RP2040 |
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|:-----------|:------------------------------------------------------------ |
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| Family | (2x) ARM Cortex-M0+ |
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| Vendor | Raspberry Pi |
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| RAM | 264 KiB |
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| Flash | 2 MiB (up to 16 MiB) |
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| Frequency | up to 133 MHz |
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| FPU | no |
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| PIOs | 8 |
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| Timers | 1 x 64-bit |
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| ADCs | 1x 12-bit (4 channels + temperature sensor) |
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| UARTs | 2 |
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| SPIs | 2 |
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| I2Cs | 2 |
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| RTCs | 1 |
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| USBs | 1 (USB 2.0) |
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| Watchdog | 1 |
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| SSI/QSPI | 1 (connected to flash, with XIP support) |
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| Vcc | 1.62V - 3.63V |
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| Datasheet | [Datasheet](https://datasheets.raspberrypi.com/pico/pico-datasheet.pdf) |
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### User Interface
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1 button (also used for boot selection) and 1 LED:
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| Device | PIN |
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|:------ |:---------------- |
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| LED0 | 25 |
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| SW0 | QSPI_SS_N (*) |
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(*) Since the switch is connected to the chip-select pin of the QSPI interface the flash chip RIOT
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is running from via XIP, the switch is difficult to read out from software. This is currently not
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supported.
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### Pinout
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## Flashing the Board
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### Flashing the Board Using the Bootloader
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Connect the device to your Micro-USB cable while the button (labeled `BOOTSEL`
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on the silkscreen of the PCB) is pressed to enter the bootloader. The pico
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will present itself as a storage medium to the system, to which a UF2 file
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can be copied perform the flashing of the device. This can be automated by
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running:
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```
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make BOARD=rpi-pico flash
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```
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This is default flashing option using elf2uf2 PROGRAMMER. If the storage is
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not automatically mounted to `/media/<USER_NAME>/RPI-RP2`, you can overwrite
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the path by exporting the shell environment variable `ELF2UF2_MOUNT_PATH`.
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### Flashing the Board Using OpenOCD
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Currently (June 2021), only two methods for debugging via OpenOCD are supported:
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1. Using a bit-banging low-level adapter, e.g. via the GPIOs of a Raspberry Pi 4B
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2. Using a virtual CMSIS-DAP adapter provided by the second CPU core via
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https://github.com/majbthrd/pico-debug
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Option 2 requires no additional hardware however, you need to
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first "flash" the gimme-cache variant of [pico-debug](https://github.com/majbthrd/pico-debug)
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into RAM using the UF2 bootloader. For this, plug in the USB cable while holding down the BOOTSEL
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button of the Pico and copy the `pico-debug-gimmecache.uf2` from the
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[latest pico-debug release](https://github.com/majbthrd/pico-debug/releases) into the virtual FAT
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formatted drive the bootloader provides. Once this drive is unmounted again, this will result in
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the Raspberry Pi Pico showing up as CMSIS-DAP debugger. Afterwards run:
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```
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make BOARD=rpi-pico PROGRAMMER=openocd flash
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```
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@warning The `rpi-pico` virtual debugger is not persistent and needs to be "flashed" into RAM
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again after each cold boot.
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@note As of July 2021, the latest stable release of OpenOCD does not yet support the RP2040
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MCU. Instead, compile the current `master` branch from the upstream OpenOCD source.
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The OpenOCD fork of the Raspberry Pi foundation is incompatible with OpenOCD
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configuration provided, so please stick with upstream OpenOCD.
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### Flashing the Board Using J-Link
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Connect the Board to an Segger J-Link debugger, e.g. the EDU mini debugger is relatively affordable,
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but limited to educational purposes. Afterwards run:
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```
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make BOARD=rpi-pico PROGRAMMER=jlink flash
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```
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## Accessing RIOT shell
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This board's default access to RIOT shell is via UART (UART0 TX - pin 1, UART0 RX - pin 2).
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The default baud rate is 115 200.
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The simplest way to connect to the shell is the execution of the command:
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```
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make BOARD=rpi-pico term
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```
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@warning Raspberry Pi Pico board is not 5V tolerant. Use voltage divider or logic level shifter when connecting to 5V UART.
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## On-Chip Debugging
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There are currently (June 2021) few hardware options for debugging the Raspberry Pi Pico:
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1. Via J-Link using one of Seggers debuggers
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2. Via OpenOCD using a low-level bit-banging debugger (e.g. a Raspberry Pi 4B with the GPIOs
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connected to the Raspberry Pi Pico via jump wires)
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3. Via a recently updated [Black Magic Probe](https://github.com/blacksphere/blackmagic)
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In addition, a software-only option is possible using
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[pico-debug](https://github.com/majbthrd/pico-debug). The default linker script reserved 16 KiB of
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RAM for this debugger, hence just "flash" the "gimme-cache" flavor into RAM using the UF2
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bootloader. Once this is done, debugging is as simple as running:
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```
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make BOARD=rpi-pico debug
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```
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***Beware:*** The `rpi-pico` virtual debugger is not persistent and needs to be "flashed" into RAM
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again after each cold boot. The initialization code of RIOT now seems to play well with the
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debugger, so it remains persistent on soft reboots. If you face issues with losing connection to
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the debugger on reboot, try `monitor reset init` in GDB to soft-reboot instead.
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## Known Issues / Problems
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### Early state Implementation
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Currently no support for the following peripherals is implemented:
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- Timers
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- ADC
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- SPI
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- I2C
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- USB
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- PIO
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- RTC
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- Watchdog
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- SMP support (multi CPU support is not implemented in RIOT)
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*/
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