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abort an attempted i2c hard reset if attempted toggling of SDA, SCL does not free up lines.

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This commit is contained in:
Andre Devitt
2012-02-20 16:57:25 -05:00
parent 0c2b9bdb05
commit 0de495c4a0
1 changed files with 20 additions and 4 deletions
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sw/airborne/arch/stm32/mcu_periph/i2c_arch.c
+20 -4
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@@ -13,6 +13,10 @@ static inline void i2c_reset_init(struct i2c_periph *p);
#define I2C_BUSY 0x20
// If a hard reset cannot free up SDA, SCL lines abort. Previously stm32 would hang
// when lines stuck i.e. no pullups on I2C lines
#define I2C_MAX_RESET_FAIL_COUNT 20
#ifdef DEBUG_I2C
#define SPURIOUS_INTERRUPT(_periph, _status, _event) { while(1); }
#define OUT_OF_SYNC_STATE_MACHINE(_periph, _status, _event) { while(1); }
@@ -355,6 +359,7 @@ static inline void i2c_error(struct i2c_periph *p)
static inline void i2c_hard_reset(struct i2c_periph *p)
{
uint8_t timeout_fails=0;
I2C_TypeDef *regs = (I2C_TypeDef *) p->reg_addr;
I2C_DeInit(p->reg_addr);
@@ -366,10 +371,13 @@ static inline void i2c_hard_reset(struct i2c_periph *p)
GPIO_SetBits(GPIOB, p->scl_pin | p->sda_pin);
GPIO_Init(GPIOB, &GPIO_InitStructure);
while(GPIO_ReadInputDataBit(GPIOB, p->sda_pin) == Bit_RESET) {
while((GPIO_ReadInputDataBit(GPIOB, p->sda_pin) == Bit_RESET) && timeout_fails < I2C_MAX_RESET_FAIL_COUNT) {
// Raise SCL, wait until SCL is high (in case of clock stretching)
GPIO_SetBits(GPIOB, p->scl_pin);
while (GPIO_ReadInputDataBit(GPIOB, p->scl_pin) == Bit_RESET);
while ((GPIO_ReadInputDataBit(GPIOB, p->scl_pin) == Bit_RESET) && timeout_fails < I2C_MAX_RESET_FAIL_COUNT) {
i2c_delay();
timeout_fails++;
}
i2c_delay();
// Lower SCL, wait
@@ -379,6 +387,7 @@ static inline void i2c_hard_reset(struct i2c_periph *p)
// Raise SCL, wait
GPIO_SetBits(GPIOB, p->scl_pin);
i2c_delay();
timeout_fails++;
}
// Generate a start condition followed by a stop condition
@@ -391,10 +400,17 @@ static inline void i2c_hard_reset(struct i2c_periph *p)
// Raise both SCL and SDA and wait for SCL high (in case of clock stretching)
GPIO_SetBits(GPIOB, p->scl_pin | p->sda_pin);
while (GPIO_ReadInputDataBit(GPIOB, p->scl_pin) == Bit_RESET);
while (GPIO_ReadInputDataBit(GPIOB, p->scl_pin) == Bit_RESET && timeout_fails < I2C_MAX_RESET_FAIL_COUNT) {
i2c_delay();
timeout_fails++;
}
// Wait for SDA to be high
while (GPIO_ReadInputDataBit(GPIOB, p->sda_pin) != Bit_SET);
while (GPIO_ReadInputDataBit(GPIOB, p->sda_pin) != Bit_SET && timeout_fails < I2C_MAX_RESET_FAIL_COUNT)
{
i2c_delay();
timeout_fails++;
}
// SCL and SDA should be high at this point, bus should be free
// Return the GPIO pins to the alternate function