Posted on May 07, 2016 at 16:00
Reference manual RM0383, ''STM32F411xC/E advanced ARM®-based 32-bit MCUs'', says:
6.7 I2C Status register 2 (I2C_SR2)
Note: Reading I2C_SR2 after reading I2C_SR1 clears the ADDR flag, even if the ADDR flag wasset after reading I2C_SR1. Consequently, I2C_SR2 must be read only when ADDR is foundset in I2C_SR1 or when the STOPF bit is cleared.
But theSTM32F4 DSP and standard peripherals library, STSW-STM32065,
does not do this in I2C_CheckEvent():
ErrorStatus I2C_CheckEvent(I2C_TypeDef* I2Cx, uint32_t I2C_EVENT)
{
uint32_t lastevent = 0;
uint32_t flag1 = 0, flag2 = 0;
ErrorStatus status = ERROR;
/* Check the parameters */
assert_param(IS_I2C_ALL_PERIPH(I2Cx));
assert_param(IS_I2C_EVENT(I2C_EVENT));
/* Read the I2Cx status register */
flag1 = I2Cx->SR1;
flag2 = I2Cx->SR2;
flag2 = flag2 << 16;
It will always read SR2 immediately after SR1 - without any attempt to check ADDR or STOPF.
I guess it should look something like this:
/* Read the I2Cx status registers */
flag1 = I2Cx->SR1;
/*
* RM0383 states, ''I2C_SR2 must be read only when ADDR is found
* set in I2C_SR1 or when the STOPF bit is cleared''
* See section 6.7 I2C Status register 2 (I2C_SR2) on page 492 (Rev 1).
*/
if( (flag1 & I2C_SR1_ADDR) ||
(flag1 & ~I2C_SR1_STOPF) )
{
flag2 = I2Cx->SR2;
}
else
{
return ERROR;
}
(can't raise a ticket on this as the system is down for ''upgrades'').
This is in the current 1.7.0 library release, and previous releases.
#library #stm32f4 #i2c
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