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bugfix(i2c): reduce speed of I2C master bus reset routine and release SDA

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closes https://github.com/espressif/esp-idf/issues/2494
closes https://github.com/espressif/esp-idf/pull/2493
closes https://github.com/espressif/esp-idf/pull/2496

1. Change bus reset to handle interrupted READ sequences.
2. Slow down I2C to 100khz during reset
3. If a SLAVE device was in a read operation when the bus was interrupted, the SLAVE device is controlling SDA.The only bit during the 9 clock cycles of a byte READ the MASTER(ESP32) is guaranteed control over, is during the ACK bit period.
If the SLAVE is sending a stream of ZERO bytes, it will only release SDA during the ACK bit period. The master(ESP32) cannot generate a STOP unless SDA is HIGH. So, this reset code synchronizes the bit stream with, Either, the ACK bit, Or a 1 bit.
This commit is contained in:
Wangjialin 2018-11-28 15:41:46 +08:00 committed by morris
parent 929d98538e
commit 553ba51924
1 changed files with 7 additions and 6 deletions
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13
components/driver/i2c.c
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@ -80,6 +80,8 @@ static DRAM_ATTR i2c_dev_t* const I2C[I2C_NUM_MAX] = { &I2C0, &I2C1 };
#define I2C_MASTER_TOUT_CNUM_DEFAULT (8) /* I2C master timeout cycle number of I2C clock, after which the timeout interrupt will be triggered */
#define I2C_ACKERR_CNT_MAX (10)
#define I2C_FILTER_CYC_NUM_DEF (7) /* The number of apb cycles filtered by default*/
#define I2C_CLR_BUS_SCL_NUM (9)
#define I2C_CLR_BUS_HALF_PERIOD_US (5)
typedef struct {
uint8_t byte_num; /*!< cmd byte number */
@ -525,7 +527,9 @@ esp_err_t i2c_get_data_mode(i2c_port_t i2c_num, i2c_trans_mode_t *tx_trans_mode,
static esp_err_t i2c_master_clear_bus(i2c_port_t i2c_num)
{
I2C_CHECK(i2c_num < I2C_NUM_MAX, I2C_NUM_ERROR_STR, ESP_ERR_INVALID_ARG);
const int scl_half_period = I2C_CLR_BUS_HALF_PERIOD_US; // use standard 100kHz data rate
int sda_in_sig = 0, scl_in_sig = 0;
int i = 0;
if (i2c_num == I2C_NUM_0) {
sda_in_sig = I2CEXT0_SDA_IN_IDX;
scl_in_sig = I2CEXT0_SCL_IN_IDX;
@ -536,25 +540,22 @@ static esp_err_t i2c_master_clear_bus(i2c_port_t i2c_num)
int scl_io = GPIO.func_in_sel_cfg[scl_in_sig].func_sel;
int sda_io = GPIO.func_in_sel_cfg[sda_in_sig].func_sel;
I2C_CHECK((GPIO_IS_VALID_OUTPUT_GPIO(scl_io)), I2C_SCL_IO_ERR_STR, ESP_ERR_INVALID_ARG);
I2C_CHECK((GPIO_IS_VALID_GPIO(sda_io)), I2C_SDA_IO_ERR_STR, ESP_ERR_INVALID_ARG);
I2C_CHECK((GPIO_IS_VALID_OUTPUT_GPIO(sda_io)), I2C_SDA_IO_ERR_STR, ESP_ERR_INVALID_ARG);
gpio_set_direction(scl_io, GPIO_MODE_OUTPUT_OD);
gpio_set_direction(sda_io, GPIO_MODE_OUTPUT_OD);
gpio_set_direction(sda_io, GPIO_MODE_INPUT_OUTPUT_OD);
// If a SLAVE device was in a read operation when the bus was interrupted, the SLAVE device is controlling SDA.
// The only bit during the 9 clock cycles of a READ byte the MASTER(ESP32) is guaranteed control over is during the ACK bit
// period. If the slave is sending a stream of ZERO bytes, it will only release SDA during the ACK bit period.
// So, this reset code needs to synchronize the bit stream with, Either, the ACK bit, Or a 1 bit to correctly generate
// a STOP condition.
int scl_half_period = 5; // use standard 100kHz data rate
gpio_set_level(scl_io, 0);
gpio_set_level(sda_io, 1);
ets_delay_us(scl_half_period);
int i=0;
while( !gpio_get_level(sda_io) && (i<9)){ // cycle SCL until SDA is HIGH
while(!gpio_get_level(sda_io) && (i++ < I2C_CLR_BUS_SCL_NUM)) {
gpio_set_level(scl_io, 1);
ets_delay_us(scl_half_period);
gpio_set_level(scl_io, 0);
ets_delay_us(scl_half_period);
i++;
}
gpio_set_level(sda_io,0); // setup for STOP
gpio_set_level(scl_io,1);