Posted on December 30, 2014 at 19:38 Hi Folks:
I modified I2C_CheckEvent(), as illustrated below, to prevent
the I2C SR1 register from being read twice in the case of
overly anxious compilers and optimizers. The solution is
not elegant or sophisticated but works. Basically, it
involves using the volatile qualifier and computing the
register address before accessing the register. A potential
drawback is the use of a hardcoded register offset.
Best Regards,
Paul R.
ErrorStatus I2C_CheckEvent(I2C_TypeDef* I2Cx, uint32_t I2C_EVENT)
{
uint32_t lastevent = 0;
volatile uint32_t flag1 = 0, flag2 = 0;
volatile uint32_t *p_sr1;
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 */
p_sr1 = (volatile uint32_t *) ((void *) I2Cx + I2C_Register_SR1);
flag1 = *p_sr1;
flag2 = I2Cx->SR2;
flag2 = flag2 << 16;
/* Get the last event value from I2C status register */
lastevent = (flag1 | flag2) & FLAG_MASK;
/* Check whether the last event contains the I2C_EVENT */
if ((lastevent & I2C_EVENT) == I2C_EVENT)
{
/* SUCCESS: last event is equal to I2C_EVENT */
status = SUCCESS;
}
else
{
/* ERROR: last event is different from I2C_EVENT */
status = ERROR;
}
/* Return status */
return status;
}
