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STM32 I2C: Replace call to wait_us by a sw loop #6538

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STM32 I2C: Replace call to wait_us by a sw loop #6538

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83fe2ba
STM32 I2C: change the call to wait_us
bcostm Apr 3, 2018
3ffc588
STM32 I2C: use a function instead of a macro
bcostm Apr 5, 2018
4f966ed
STM32 I2C: use us_ticker_read
bcostm Apr 5, 2018
7e8a9a1
STM32 I2C: rename the wait function
bcostm Apr 10, 2018
e698f89
STM32 I2C: add timeout check and simplify wait loop
bcostm Apr 16, 2018
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54 changes: 34 additions & 20 deletions targets/TARGET_STM/i2c_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,17 +28,15 @@
*******************************************************************************
*/

#if DEVICE_I2C

#include "mbed_assert.h"
#include "i2c_api.h"
#include "platform/mbed_wait_api.h"

#if DEVICE_I2C

#include "cmsis.h"
#include "pinmap.h"
#include "PeripheralPins.h"
#include "i2c_device.h" // family specific defines
#include "hal/us_ticker_api.h"

#ifndef DEBUG_STDIO
# define DEBUG_STDIO 0
Expand All @@ -61,24 +59,40 @@
#define I2C_NUM (5)
static I2C_HandleTypeDef* i2c_handles[I2C_NUM];

/* Timeout values are based on core clock and I2C clock.
The BYTE_TIMEOUT is computed as twice the number of cycles it would
/* Timeout value based on Core and I2C clocks */
#define BYTE_TIMEOUT (SystemCoreClock / obj_s->hz)

/* The BYTE_TIMEOUT_20 is computed as twice the number of cycles it would
take to send 10 bits over I2C. Most Flags should take less than that.
This is for immediate FLAG or ACK check.
*/
#define BYTE_TIMEOUT ((SystemCoreClock / obj_s->hz) * 2 * 10)
/* Timeout values based on I2C clock.
The BYTE_TIMEOUT_US is computed as 3x the time in us it would
#define BYTE_TIMEOUT_20 (BYTE_TIMEOUT * 2 * 10)

/* The BYTE_TIMEOUT_30 is computed as 3x the time in us it would
take to send 10 bits over I2C. Most Flags should take less than that.
This is for complete transfers check.
*/
#define BYTE_TIMEOUT_US ((SystemCoreClock / obj_s->hz) * 3 * 10)
#define BYTE_TIMEOUT_30 (BYTE_TIMEOUT * 3 * 10)

/* Timeout values for flags and events waiting loops. These timeouts are
not based on accurate values, they just guarantee that the application will
not remain stuck if the I2C communication is corrupted.
*/
#define FLAG_TIMEOUT ((int)0x1000)

/* This function assumes the tick is 1 us */
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At a minimum should also comment that it assumes it's 32-bit - not sure if@LMESTM is happy with that assumption for this patch, given his comments.

static void wait_loop_us(uint32_t timeout)
{
uint32_t t1, t2, elapsed = 0;
if (timeout > 0) {
t1 = us_ticker_read();
do {
t2 = us_ticker_read();
elapsed = t2 - t1;
} while (elapsed < timeout);
}
}

/* GENERIC INIT and HELPERS FUNCTIONS */

#if defined(I2C1_BASE)
Expand Down Expand Up @@ -204,7 +218,7 @@ void i2c_hw_reset(i2c_t *obj) {
handle->Instance = (I2C_TypeDef *)(obj_s->i2c);

// wait before reset
timeout = BYTE_TIMEOUT;
timeout = BYTE_TIMEOUT_20;
while ((__HAL_I2C_GET_FLAG(handle, I2C_FLAG_BUSY)) && (--timeout != 0));
#if defined I2C1_BASE
if (obj_s->i2c == I2C_1) {
Expand Down Expand Up @@ -352,7 +366,7 @@ void i2c_frequency(i2c_t *obj, int hz)
I2C_HandleTypeDef *handle = &(obj_s->handle);

// wait before init
timeout = BYTE_TIMEOUT;
timeout = BYTE_TIMEOUT_20;
while ((__HAL_I2C_GET_FLAG(handle, I2C_FLAG_BUSY)) && (--timeout != 0));

#ifdef I2C_IP_VERSION_V1
Expand Down Expand Up @@ -751,10 +765,10 @@ int i2c_read(i2c_t *obj, int address, char *data, int length, int stop) {
ret = HAL_I2C_Master_Sequential_Receive_IT(handle, address, (uint8_t *) data, length, obj_s->XferOperation);

if(ret == HAL_OK) {
timeout = BYTE_TIMEOUT_US * (length + 1);
timeout = BYTE_TIMEOUT_30 * (length + 1);
/* transfer started : wait completion or timeout */
while(!(obj_s->event & I2C_EVENT_ALL) && (--timeout != 0)) {
wait_us(1);
wait_loop_us(1);
}

i2c_ev_err_disable(obj);
Expand Down Expand Up @@ -802,10 +816,10 @@ int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
ret = HAL_I2C_Master_Sequential_Transmit_IT(handle, address, (uint8_t *) data, length, obj_s->XferOperation);

if(ret == HAL_OK) {
timeout = BYTE_TIMEOUT_US * (length + 1);
timeout = BYTE_TIMEOUT_30 * (length + 1);
/* transfer started : wait completion or timeout */
while(!(obj_s->event & I2C_EVENT_ALL) && (--timeout != 0)) {
wait_us(1);
wait_loop_us(1);
}

i2c_ev_err_disable(obj);
Expand Down Expand Up @@ -984,9 +998,9 @@ int i2c_slave_read(i2c_t *obj, char *data, int length) {
ret = HAL_I2C_Slave_Sequential_Receive_IT(handle, (uint8_t *) data, length, I2C_NEXT_FRAME);

if(ret == HAL_OK) {
timeout = BYTE_TIMEOUT_US * (length + 1);
timeout = BYTE_TIMEOUT_30 * (length + 1);
while(obj_s->pending_slave_rx_maxter_tx && (--timeout != 0)) {
wait_us(1);
wait_loop_us(1);
}

if(timeout != 0) {
Expand All @@ -1009,9 +1023,9 @@ int i2c_slave_write(i2c_t *obj, const char *data, int length) {
ret = HAL_I2C_Slave_Sequential_Transmit_IT(handle, (uint8_t *) data, length, I2C_NEXT_FRAME);

if(ret == HAL_OK) {
timeout = BYTE_TIMEOUT_US * (length + 1);
timeout = BYTE_TIMEOUT_30 * (length + 1);
while(obj_s->pending_slave_tx_master_rx && (--timeout != 0)) {
wait_us(1);
wait_loop_us(1);
}

if(timeout != 0) {
Expand Down