circuitpython/ports/stm32/i2c.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2018 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "py/mperrno.h"
#include "py/mphal.h"
#include "i2c.h"
#if MICROPY_HW_ENABLE_HW_I2C
#if defined(STM32F7)
#define I2C_POLL_TIMEOUT_MS (50)
int i2c_init(i2c_t *i2c, mp_hal_pin_obj_t scl, mp_hal_pin_obj_t sda, uint32_t freq) {
uint32_t i2c_id = ((uint32_t)i2c - I2C1_BASE) / (I2C2_BASE - I2C1_BASE);
// Init pins
if (!mp_hal_pin_config_alt(scl, MP_HAL_PIN_MODE_ALT_OPEN_DRAIN, MP_HAL_PIN_PULL_UP, AF_FN_I2C, i2c_id + 1)) {
return -MP_EPERM;
}
if (!mp_hal_pin_config_alt(sda, MP_HAL_PIN_MODE_ALT_OPEN_DRAIN, MP_HAL_PIN_PULL_UP, AF_FN_I2C, i2c_id + 1)) {
return -MP_EPERM;
}
// Enable I2C peripheral clock
RCC->APB1ENR |= RCC_APB1ENR_I2C1EN << i2c_id;
volatile uint32_t tmp = RCC->APB1ENR; // delay after RCC clock enable
(void)tmp;
// Initialise I2C peripheral
i2c->CR1 = 0;
i2c->CR2 = 0;
i2c->OAR1 = 0;
i2c->OAR2 = 0;
// These timing values are for f_I2CCLK=54MHz and are only approximate
if (freq >= 1000000) {
i2c->TIMINGR = 0x50100103;
} else if (freq >= 400000) {
i2c->TIMINGR = 0x70330309;
} else if (freq >= 100000) {
i2c->TIMINGR = 0xb0420f13;
} else {
return -MP_EINVAL;
}
i2c->TIMEOUTR = 0;
return 0;
}
STATIC int i2c_wait_cr2_clear(i2c_t *i2c, uint32_t mask) {
uint32_t t0 = HAL_GetTick();
while (i2c->CR2 & mask) {
if (HAL_GetTick() - t0 >= I2C_POLL_TIMEOUT_MS) {
i2c->CR1 &= ~I2C_CR1_PE;
return -MP_ETIMEDOUT;
}
}
return 0;
}
STATIC int i2c_wait_isr_set(i2c_t *i2c, uint32_t mask) {
uint32_t t0 = HAL_GetTick();
while (!(i2c->ISR & mask)) {
if (HAL_GetTick() - t0 >= I2C_POLL_TIMEOUT_MS) {
i2c->CR1 &= ~I2C_CR1_PE;
return -MP_ETIMEDOUT;
}
}
return 0;
}
// len = 0, 1 or N
int i2c_start_addr(i2c_t *i2c, int rd_wrn, uint16_t addr, size_t len, bool stop) {
// Enable the peripheral and send the START condition with slave address
i2c->CR1 |= I2C_CR1_PE;
i2c->CR2 = stop << I2C_CR2_AUTOEND_Pos
| (len > 1) << I2C_CR2_RELOAD_Pos
| (len > 0) << I2C_CR2_NBYTES_Pos
| rd_wrn << I2C_CR2_RD_WRN_Pos
| (addr & 0x7f) << 1;
i2c->CR2 |= I2C_CR2_START;
// Wait for address to be sent
int ret;
if ((ret = i2c_wait_cr2_clear(i2c, I2C_CR2_START))) {
return ret;
}
// Check if the slave responded or not
if (i2c->ISR & I2C_ISR_NACKF) {
// If we get a NACK then I2C periph unconditionally sends a STOP
i2c_wait_isr_set(i2c, I2C_ISR_STOPF); // Don't leak errors from this call
i2c->CR1 &= ~I2C_CR1_PE;
return -MP_ENODEV;
}
// Repurpose OAR1 to indicate that we loaded CR2
i2c->OAR1 = 1;
return 0;
}
STATIC int i2c_check_stop(i2c_t *i2c) {
if (i2c->CR2 & I2C_CR2_AUTOEND) {
// Wait for the STOP condition and then disable the peripheral
int ret;
if ((ret = i2c_wait_isr_set(i2c, I2C_ISR_STOPF))) {
return ret;
}
i2c->CR1 &= ~I2C_CR1_PE;
}
return 0;
}
// next_len = 0 or N
int i2c_read(i2c_t *i2c, uint8_t *dest, size_t len, size_t next_len) {
if (i2c->OAR1) {
i2c->OAR1 = 0;
} else {
goto load_cr2;
}
// Read in the data
while (len--) {
int ret;
if ((ret = i2c_wait_isr_set(i2c, I2C_ISR_RXNE))) {
return ret;
}
*dest++ = i2c->RXDR;
load_cr2:
if (len) {
i2c->CR2 = (i2c->CR2 & I2C_CR2_AUTOEND)
| (len + next_len > 1) << I2C_CR2_RELOAD_Pos
| 1 << I2C_CR2_NBYTES_Pos;
}
}
if (!next_len) {
int ret;
if ((ret = i2c_check_stop(i2c))) {
return ret;
}
}
return 0;
}
// next_len = 0 or N
int i2c_write(i2c_t *i2c, const uint8_t *src, size_t len, size_t next_len) {
int num_acks = 0;
if (i2c->OAR1) {
i2c->OAR1 = 0;
} else {
goto load_cr2;
}
// Write out the data
while (len--) {
int ret;
if ((ret = i2c_wait_isr_set(i2c, I2C_ISR_TXE))) {
return ret;
}
i2c->TXDR = *src++;
if ((ret = i2c_wait_isr_set(i2c, I2C_ISR_TCR | I2C_ISR_TC | I2C_ISR_STOPF))) {
return ret;
}
if (i2c->ISR & I2C_ISR_NACKF) {
// Slave did not respond to byte so stop sending
break;
}
++num_acks;
load_cr2:
if (len) {
i2c->CR2 = (i2c->CR2 & I2C_CR2_AUTOEND)
| (len + next_len > 1) << I2C_CR2_RELOAD_Pos
| 1 << I2C_CR2_NBYTES_Pos;
}
}
if (!next_len) {
int ret;
if ((ret = i2c_check_stop(i2c))) {
return ret;
}
}
return num_acks;
}
int i2c_readfrom(i2c_t *i2c, uint16_t addr, uint8_t *dest, size_t len, bool stop) {
int ret;
if ((ret = i2c_start_addr(i2c, 1, addr, len, stop))) {
return ret;
}
return i2c_read(i2c, dest, len, 0);
}
int i2c_writeto(i2c_t *i2c, uint16_t addr, const uint8_t *src, size_t len, bool stop) {
int ret;
if ((ret = i2c_start_addr(i2c, 0, addr, len, stop))) {
return ret;
}
return i2c_write(i2c, src, len, 0);
}
#endif // defined(STM32F7)
#endif // MICROPY_HW_ENABLE_HW_I2C