Posted on May 17, 2011 at 14:19Hello,
The initialization code is basically the same than AN:
void TIMEOUT_Init(TIM_TypeDef *tim) {
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_ICInitTypeDef TIM_ICInitStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
if (tim == NULL) {
return;
}
/* Stop timer */
TIM_Cmd(tim, DISABLE);
/* UEV disabled */
TIM_UpdateDisableConfig(tim, ENABLE);
/* Timer base configuration */
TIM_TimeBaseStructure.TIM_Prescaler = 0x1; /* Ignored in Slave Mode */
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period = 65535; /* Maximum period */
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseInit(tim, &TIM_TimeBaseStructure);
/* Enable One-Pulse mode, so counter stops at UEV */
TIM_SelectOnePulseMode(tim, TIM_OPMode_Single);
/* Input Capture Configuration: Channel 1 */
TIM_ICStructInit(&TIM_ICInitStructure);
TIM_ICInitStructure.TIM_Channel = TIM_Channel_1;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM_ICInitStructure.TIM_ICFilter = 0;
TIM_ICInit(tim, &TIM_ICInitStructure);
/* Output Compare Mode configuration: Channel2 */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Timing;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Disable;
TIM_OCInitStructure.TIM_Pulse = (uint16_t)0xFFFF; /* Timeout value */
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
TIM_OC2Init(tim, &TIM_OCInitStructure);
/* Timer Input trigger configuration: input connected to TI1 */
TIM_SelectInputTrigger(tim, TIM_TS_TI1FP1);
/* Timer configuration in slave reset mode where the timer counter is
re-initialized in response to rising edges on the input capture (TI1) */
TIM_SelectSlaveMode(tim, TIM_SlaveMode_Reset);
/* Global Interrupt mode */
tim->CR1 &= (~TIM_CR1_URS);
/* Update ARR, PSC and CCR shadow regs by setting UG bit in EGR reg */
TIM_GenerateEvent(tim, TIM_EventSource_Update);
}
Interrupt handler starts the counter when the first byte is received (first rising edge in Rx input) until the counter matchs OC value. The problem is that TIM_Prescaler is ignored in slave mode (as mentioned in the reference manual), so counter frequency is too fast for UART common baudrates. If you could find a workaround to fix this, it will be really appreciated.
Thank you.
