From fd13e0064db0f3c8ab0e73a71b4073d8e7a8c77b Mon Sep 17 00:00:00 2001 From: "Matthias P. Braendli" Date: Sun, 20 Dec 2015 16:29:02 +0100 Subject: Properly reset I2C bus in case of error --- src/fsm/i2c.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 98 insertions(+), 26 deletions(-) (limited to 'src/fsm/i2c.c') diff --git a/src/fsm/i2c.c b/src/fsm/i2c.c index b1b5e3a..8398b58 100644 --- a/src/fsm/i2c.c +++ b/src/fsm/i2c.c @@ -39,8 +39,72 @@ static I2C_TypeDef* const I2Cx = I2C1; static SemaphoreHandle_t i2c_semaphore; +static void i2c_device_init(void); + +/* According to I2C spec UM10204: + * 3.1.16 Bus clear + * In the unlikely event where the clock (SCL) is stuck LOW, the preferential + * procedure is to reset the bus using the HW reset signal if your I2C devices + * have HW reset inputs. If the I2C devices do not have HW reset inputs, cycle + * power to the devices to activate the mandatory internal Power-On Reset (POR) + * circuit. + * + * If the data line (SDA) is stuck LOW, the master should send nine clock + * pulses. The device that held the bus LOW should release it sometime within + * those nine clocks. If not, then use the HW reset or cycle power to clear the + * bus. + */ +static void i2c_recover_from_lockup(void) +{ + I2C_SoftwareResetCmd(I2Cx, ENABLE); + + // Configure I2C SCL and SDA pins. + GPIO_InitTypeDef GPIO_InitStructure; + GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_9; + GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; + GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; + GPIO_InitStructure.GPIO_OType = GPIO_OType_OD; + GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; + GPIO_Init(GPIOB, &GPIO_InitStructure); + + const uint16_t pin_sda = GPIO_Pin_9; + const uint16_t pin_scl = GPIO_Pin_6; + + const TickType_t delay = 5 / portTICK_PERIOD_MS; + + GPIO_SetBits(GPIOB, pin_sda | pin_scl); + vTaskDelay(delay); + + I2C_SoftwareResetCmd(I2Cx, ENABLE); + + for (int i = 0; i < 10; i++) { + GPIO_ResetBits(GPIOB, pin_scl); + vTaskDelay(delay); + GPIO_SetBits(GPIOB, pin_scl); + vTaskDelay(delay); + } + + i2c_device_init(); +} + static void i2c_device_init(void) { + // Configure I2C SCL and SDA pins. + GPIO_InitTypeDef GPIO_InitStructure; + GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_9; + GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; + GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF; + GPIO_InitStructure.GPIO_OType = GPIO_OType_OD; + GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; + GPIO_Init(GPIOB, &GPIO_InitStructure); + + GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_I2C1); + GPIO_PinAFConfig(GPIOB, GPIO_PinSource9, GPIO_AF_I2C1); + + // Reset I2C. + RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2C1, ENABLE); + RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2C1, DISABLE); + // configure I2C1 I2C_InitTypeDef I2C_InitStruct; I2C_InitStruct.I2C_ClockSpeed = 100000; //Hz @@ -76,24 +140,25 @@ void i2c_init() RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE); RCC_APB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE); - // Configure I2C SCL and SDA pins. - GPIO_InitTypeDef GPIO_InitStructure; - GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_9; - GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; - GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF; - GPIO_InitStructure.GPIO_OType = GPIO_OType_OD; - GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; - GPIO_Init(GPIOB, &GPIO_InitStructure); + i2c_device_init(); + i2c_init_done = 1; +} - GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_I2C1); - GPIO_PinAFConfig(GPIOB, GPIO_PinSource9, GPIO_AF_I2C1); +static int i2c_check_busy_flag(void) +{ + const TickType_t i2c_timeout = 1000ul / portTICK_PERIOD_MS; + const TickType_t time_start = xTaskGetTickCount(); - // Reset I2C. - RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2C1, ENABLE); - RCC_APB1PeriphResetCmd(RCC_APB1Periph_I2C1, DISABLE); + while (I2C_GetFlagStatus(I2Cx, I2C_FLAG_BUSY)) { + const TickType_t time_now = xTaskGetTickCount(); - i2c_device_init(); - i2c_init_done = 1; + if (time_now - time_start > i2c_timeout) { + i2c_error = 1; + return 0; + } + } + + return 1; } static int i2c_check_event(uint32_t event) @@ -105,6 +170,7 @@ static int i2c_check_event(uint32_t event) const TickType_t time_now = xTaskGetTickCount(); if (time_now - time_start > i2c_timeout) { + i2c_error = 1; return 0; } } @@ -161,11 +227,13 @@ int i2c_write(uint8_t device, const uint8_t *txbuf, int len) trigger_fault(FAULT_SOURCE_I2C); } - while (I2C_GetFlagStatus(I2Cx, I2C_FLAG_BUSY)); + int success = i2c_check_busy_flag(); - int success = 0; + if (success) { + success = i2c_start(device, I2C_Direction_Transmitter); + } - if (i2c_start(device, I2C_Direction_Transmitter)) { + if (success) { for (int i = 0; i < len; i++) { success = i2c_send(txbuf[i]); if (!success) { @@ -215,9 +283,13 @@ static int i2c_read_nobuscheck(uint8_t device, uint8_t *rxbuf, int len) int i2c_read(uint8_t device, uint8_t *rxbuf, int len) { - while (I2C_GetFlagStatus(I2Cx, I2C_FLAG_BUSY)); + int success = i2c_check_busy_flag(); - return i2c_read_nobuscheck(device, rxbuf, len); + if (success) { + success = i2c_read_nobuscheck(device, rxbuf, len); + } + + return success; } int i2c_read_from(uint8_t device, uint8_t address, uint8_t *rxbuf, int len) @@ -226,9 +298,12 @@ int i2c_read_from(uint8_t device, uint8_t address, uint8_t *rxbuf, int len) trigger_fault(FAULT_SOURCE_I2C); } - while (I2C_GetFlagStatus(I2Cx, I2C_FLAG_BUSY)); + int success = i2c_check_busy_flag(); + + if (success) { + success = i2c_start(device, I2C_Direction_Transmitter); + } - int success = i2c_start(device, I2C_Direction_Transmitter); if (success) { success = i2c_send(address); } @@ -258,10 +333,7 @@ void i2c_transaction_end() } if ( i2c_error ) { - I2C_SoftwareResetCmd(I2Cx, ENABLE); - I2C_SoftwareResetCmd(I2Cx, DISABLE); - - i2c_device_init(); + i2c_recover_from_lockup(); i2c_error = 0; } -- cgit v1.2.3