mirror of
https://github.com/RIOT-OS/RIOT.git
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sys/arduino: Added SPI interface
Added an Arduino compatible SPI API on top of RIOT's SPI API.
This commit is contained in:
Marian Buschsieweke
parent
00926221fd
commit
cc50da690b
@ -1,5 +1,6 @@
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ifneq (,$(filter arduino,$(USEMODULE)))
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FEATURES_OPTIONAL += periph_i2c
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FEATURES_OPTIONAL += periph_spi
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endif
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ifneq (,$(filter eepreg,$(USEMODULE)))
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149
sys/arduino/SPI.cpp
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149
sys/arduino/SPI.cpp
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@ -0,0 +1,149 @@
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/*
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* Copyright (C) 2019 Otto-von-Guericke-Universität Magdeburg
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*
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* This file is subject to the terms and conditions of the GNU Lesser General
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* Public License v2.1. See the file LICENSE in the top level directory for more
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* details.
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*/
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/**
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* @ingroup sys_arduino_api
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* @{
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*
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* @file
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* @brief Implementation of the Arduino 'SPI' interface
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*
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* @author Marian Buschsieweke <marian.buschsieweke@ovgu.de>
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*
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* @}
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*/
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#ifdef MODULE_PERIPH_SPI
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extern "C" {
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#include "assert.h"
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}
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#include "SPI.h"
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SPISettings::SPISettings(uint32_t clock_hz, uint8_t bitOrder, uint8_t dataMode)
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{
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static const spi_clk_t clocks[] = {
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SPI_CLK_10MHZ, SPI_CLK_5MHZ, SPI_CLK_1MHZ, SPI_CLK_400KHZ
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};
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static const uint32_t steps [] = {
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1000000, 5000000, 1000000, 400000
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};
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assert(bitOrder == MSBFIRST);
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switch(dataMode) {
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default:
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case SPI_MODE0:
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mode = SPI_MODE_0;
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break;
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case SPI_MODE1:
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mode = SPI_MODE_1;
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break;
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case SPI_MODE2:
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mode = SPI_MODE_2;
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break;
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case SPI_MODE3:
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mode = SPI_MODE_3;
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break;
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}
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for (uint8_t i = 0; i < ARRAY_SIZE(steps); i++) {
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if (clock_hz >= steps[i]) {
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clock = clocks[i];
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return;
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}
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}
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clock = SPI_CLK_100KHZ;
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}
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SPIClass::SPIClass(spi_t spi_dev)
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{
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/* Check if default SPI interface is valid */
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BUILD_BUG_ON(ARDUINO_SPI_INTERFACE >= SPI_NUMOF);
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this->spi_dev = spi_dev;
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this->settings = SPISettings();
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this->is_transaction = false;
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rmutex_init(&this->mut);
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}
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void SPIClass::beginTransaction(SPISettings settings)
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{
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rmutex_lock(&mut);
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/* Call spi_acquire first to prevent data races */
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int retval = spi_acquire(spi_dev, SPI_CS_UNDEF,
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settings.mode, settings.clock);
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/* No support for exceptions (at least on AVR), resort to assert() */
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assert(retval == SPI_OK);
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is_transaction = true;
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}
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void SPIClass::endTransaction()
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{
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spi_release(spi_dev);
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is_transaction = false;
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rmutex_unlock(&mut);
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}
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void SPIClass::transfer(void *buf, size_t count)
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{
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rmutex_lock(&mut);
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if (!is_transaction) {
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int retval = spi_acquire(spi_dev, SPI_CS_UNDEF,
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settings.mode, settings.clock);
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/* No support for exceptions (at least on AVR), resort to assert() */
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assert(retval == SPI_OK);
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}
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spi_transfer_bytes(spi_dev, SPI_CS_UNDEF, false, buf, buf, count);
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if (!is_transaction) {
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spi_release(spi_dev);
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}
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rmutex_unlock(&mut);
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}
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void SPIClass::setBitOrder(uint8_t order)
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{
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assert(order == MSBFIRST);
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}
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void SPIClass::setDataMode(uint8_t dataMode)
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{
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switch(dataMode) {
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default:
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case SPI_MODE0:
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settings.mode = SPI_MODE_0;
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break;
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case SPI_MODE1:
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settings.mode = SPI_MODE_1;
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break;
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case SPI_MODE2:
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settings.mode = SPI_MODE_2;
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break;
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case SPI_MODE3:
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settings.mode = SPI_MODE_3;
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break;
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}
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}
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void SPIClass::setClockDivider(uint8_t divider)
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{
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static const spi_clk_t clocks[] = {
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SPI_CLK_5MHZ, SPI_CLK_1MHZ, SPI_CLK_400KHZ, SPI_CLK_100KHZ
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};
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assert(divider < ARRAY_SIZE(clocks));
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settings.clock = clocks[divider];
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}
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SPIClass SPI(SPI_DEV(ARDUINO_SPI_INTERFACE));
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#else /* MODULE_PERIPH_SPI */
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typedef int dont_be_pedantic;
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#endif /* MODULE_PERIPH_SPI */
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44
sys/arduino/include/SPI.h
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44
sys/arduino/include/SPI.h
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@ -0,0 +1,44 @@
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/*
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* Copyright (C) 2019 Otto-von-Guericke-Universität Magdeburg
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup sys_arduino
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* @{
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*
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* @file
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* @brief Wrapper to access the definition of the Arduino 'SPI' interface
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*
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* @author Marian Buschsieweke <marian.buschsieweke@ovgu.de>
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*/
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#ifndef SPI_H
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#define SPI_H
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#ifndef MODULE_PERIPH_SPI
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#error "No SPI support on your board"
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#endif
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#ifdef __cplusplus
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#include "spiport.hpp"
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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#ifndef ARDUINO_SPI_INTERFACE
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#define ARDUINO_SPI_INTERFACE 0 /**< Number of the SPI dev to make available to Arduino code */
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif /* SPI_H */
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/** @} */
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236
sys/arduino/include/spiport.hpp
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236
sys/arduino/include/spiport.hpp
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@ -0,0 +1,236 @@
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/*
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* Copyright (C) 2019 Otto-von-Guericke-Universität Magdeburg
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup sys_arduino_api
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* @{
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*
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* @file
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* @brief Definition of the Arduino 'SPI' interface
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*
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* @author Marian Buschsieweke <marian.buschsieweke@ovgu.de>
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*/
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#ifndef SPIPORT_H
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#define SPIPORT_H
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#include "arduino_board.h"
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#include "byteorder.h"
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#include "periph/spi.h"
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#include "rmutex.h"
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/**
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* @name Arduino compatible SPI modes
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* @{
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*/
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#define SPI_MODE0 (0) /**< CPOL=0, CPHA=0 */
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#define SPI_MODE1 (1) /**< CPOL=0, CPHA=1 */
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#define SPI_MODE2 (2) /**< CPOL=1, CPHA=0 */
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#define SPI_MODE3 (3) /**< CPOL=1, CPHA=1 */
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/** @} */
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/**
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* @name Arduino compatible SPI frequency selection via clock divider
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*
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* This API assumes the library was targeting a 16 MHz Arduino. It will choose
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* the SPI clock frequency matching the requested frequency best, but never
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* a frequency greater than the one it would have on Arduinos.
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* @{
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*/
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#define SPI_CLOCK_DIV2 (0) /**< Best match for 8 MHz: 5 MHz */
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#define SPI_CLOCK_DIV4 (1) /**< Best match for 4 MHz: 1 MHz */
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#define SPI_CLOCK_DIV8 (1) /**< Best match for 2 MHz: 1 MHz */
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#define SPI_CLOCK_DIV16 (1) /**< Best match for 1 MHz: 1 MHz */
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#define SPI_CLOCK_DIV32 (2) /**< Best match for 500 kHz: 400 kHz */
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#define SPI_CLOCK_DIV64 (3) /**< Best match for 250 kHZ: 100 kHz */
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#define SPI_CLOCK_DIV128 (3) /**< Best match for 125 kHz: 100 kHz */
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/** @} */
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/**
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* @name Arduino compatible bit order values for SPI
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* @{
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*/
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#define MSBFIRST (1) /**< most significat bit first */
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/** @} */
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/**
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* @brief Arduino SPI configuration interface
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*/
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class SPISettings {
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private:
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spi_mode_t mode;
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spi_clk_t clock;
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public:
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/**
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* @brief Create a new SPI settings instance
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*
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* @param clock_hz SPI clock in Hz to use
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* @param bitOrder Has to be `MSBFIST`, for compatibility only
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* @param dataMode SPI mode to use
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*
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* The RIOT SPI clock frequency best matching @p clock will be chosen,
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* but the frequency will never by greater than what is given in @p clock,
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* unless @p clock_hz is is lower than 100kHz, which is the lowest clock
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* frequency that will be used.
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*/
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SPISettings(uint32_t clock_hz, uint8_t bitOrder, uint8_t dataMode);
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/**
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* @brief Create a new SPI settings instance with default settings
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*/
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SPISettings() : SPISettings(4000000, MSBFIRST, SPI_MODE0) { }
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friend class SPIClass;
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};
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/**
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* @brief Arduino SPI interface
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*
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* @warning Wrap all SPI transfers in `SPI.beginTransaction()` and `SPI.endTransaction()`
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*
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* The official Arduino SPI-API allows to use SPI transfers without having to
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* call `SPI.beginTransaction()`, but discourages to do so. The RIOT API does
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* not provide this feature, instead a call to `SPI.beginTransaction()` is
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* mandatory. However, most Arduino code already does this and the remaining
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* code should be fixed anyway.
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*/
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class SPIClass {
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private:
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spi_t spi_dev;
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SPISettings settings;
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bool is_transaction;
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rmutex_t mut;
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public:
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/**
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* @brief Create a new SPI interface instance
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* @param spi_dev The RIOT SPI device to use under the hood
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*/
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explicit SPIClass(spi_t spi_dev);
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/**
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* @brief Create a new SPI interface instance for SPI device 0
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* @param uc_pinMISO Ignored, for compatibility only
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* @param uc_pinSCK Ignored, for compatibility only
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* @param uc_pinMOSI Ignored, for compatibility only
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* @param uc_pinSS Ignored, for compatibility only
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* @param uc_mux Ignored, for compatibility only
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*/
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SPIClass(uint8_t uc_pinMISO, uint8_t uc_pinSCK, uint8_t uc_pinMOSI,
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uint8_t uc_pinSS, uint8_t uc_mux) : SPIClass(SPI_DEV(0))
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{
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(void)uc_pinMISO;
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(void)uc_pinSCK;
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(void)uc_pinMOSI;
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(void)uc_pinSS;
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(void)uc_mux;
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}
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/**
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* @brief Transfer a single byte of data
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* @param[in] data Byte to send
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* @return The received byte
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*/
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uint8_t transfer(uint8_t data)
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{
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transfer(&data, sizeof(data));
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return data;
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}
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/**
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* @brief Transfer two bytes of data
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* @param[in] data The two bytes to send
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* @return The received two bytes
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*
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* Arduino is sending the most significant byte first, if the SPI interface
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* is configured to send the most significant bit first. If the least
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* significant bit is send first, Arduino will also send the least
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* significant byte first.
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*
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* This wrapper currently only supports sending the most significant bit
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* first over the wire, so this function will also always send the most
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* significant byte first.
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*/
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uint16_t transfer16(uint16_t data)
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{
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data = htons(data);
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transfer(&data, sizeof(data));
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return ntohs(data);
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}
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/**
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* @brief Transfer data
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* @param[inout] buf Buffer containing the data to send, received
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* data will be written here
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* @param[in] count Number of bytes to send
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*/
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void transfer(void *buf, size_t count);
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/**
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* @brief Doesn't do anything, for compatibility only
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*/
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void begin() { }
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/**
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* @brief Doesn't do anything, for compatibility only
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*/
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void end() { }
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/**
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* @brief Acquires the SPI interface and applies the given settings
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* @param[in] settings Settings to apply
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*/
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void beginTransaction(SPISettings settings);
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/**
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* @brief Releases the SPI interface
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*/
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void endTransaction();
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/**
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* @brief Sets the bit order to the given value
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*
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* @details Currently only most significant bit first is supported, as
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* practically no hardware exists using lsbfirst. An assertion
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* is triggered if lsbfirst is requested.
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* @deprecated This function is deprecated in the official Arduino API,
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* so it is a good idea to not use it. In RIOT, this function
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* is not yet scheduled for removal to allow using Arduino
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* libraries using it.
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*/
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void setBitOrder(uint8_t order);
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/**
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* @brief Sets the SPI mode (clock phase and polarity)
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*
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* @deprecated This function is deprecated in the official Arduino API,
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* so it is a good idea to not use it. In RIOT, this function
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* is not yet scheduled for removal to allow using Arduino
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* libraries using it.
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*/
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void setDataMode(uint8_t mode);
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/**
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* @brief Sets the SPI clock in an archaic manner
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*
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* @deprecated This function is deprecated in the official Arduino API,
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* so it is a good idea to not use it. In RIOT, this function
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* is not yet scheduled for removal to allow using Arduino
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* libraries using it.
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*/
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void setClockDivider(uint8_t divider);
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};
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/**
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* @brief: Instance of the SPI interface as required by the Arduino API
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*/
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extern SPIClass SPI;
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#endif /* SPIPORT_H */
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/** @} */
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