Posted by nmigliorini on 2019-04-01 11:32

I get the reply signal as I expect it on the gpio pin (baud rate, logic, and timing are ok) but for some reason the data is never moved to the RDR register of the USART (RXNE flag is set only with the first receive but when I try to read it I just get zeroes. after the first try I get only timeouts (polling mode)).

After filling the IRDA handle structure I call HAL_IRDA_DeInit() and HAL_IRDA_Init(). I configure the GPIO in HAL_IRDA_MSP_Init() and send the first message that reaches the target (with HAL_IRDA_Transmit() ). The target then is sending a reply that I can check on the UART_RX pin. And here something happens.. or better doesn’t happen. If I read the UART with HAL_IRDA_Receive() (1 byte at a time) I get only zero and then timeouts.

IRDA_HandleTypeDef hirda4;

void vIrdaInit(void)
{
hirda.Instance = USART3;
hirda.Init.BaudRate = 60100;
hirda.Init.WordLength = IRDA_WORDLENGTH_9B;
hirda.Init.Parity = IRDA_PARITY_NONE;
hirda.Init.Mode = IRDA_MODE_TX_RX;
hirda.Init.Prescaler = 1;
hirda.Init.PowerMode = IRDA_POWERMODE_NORMAL;

/* Initialize the IRDA registers. Here also HAL_IRDA_MspInit() will be called */
if (HAL_IRDA_Init(&hirda4) != HAL_OK)
{
Error_Handler();
}

}
/* Initialize IrDA low level resources. This function is called by HAL_IRDA_Init() */
void HAL_IRDA_MspInit(IRDA_HandleTypeDef* irdaHandle)
{

GPIO_InitTypeDef GPIO_InitStruct = {0};
if(irdaHandle->Instance==USART3)
{
/* UART4 clock enable */
__HAL_RCC_USART3_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();

/**UART4 GPIO Configuration
PB10 --> USART3_RX
PB11 --> USART3_TX
*/
GPIO_InitStruct.Pin = GPIO_PIN_10;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF7_UART3;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

GPIO_InitStruct.Pin = GPIO_PIN_11;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
}
}

here the call to HAL_IRDA_Transmit()/HAL_IRDA_Receive():

if(HAL_IRDA_Transmit(&hirda (uint8_t*)TxBuf, sizeof(RxBuf), 5000)!= HAL_OK)
{
Error_Handler();
}

memset(RxBuf, ‘\0’, sizeof(RxBuf));
for (i = 0; i < 8; i++)
{
// blocks here until timeout or data
if(HAL_IRDA_Receive(&hirda, (uint8_t*)RxBuf, 1, 500)!= HAL_OK)
{
Error_Handler();
}
}

With the first time in the loop, I have the RXNE flag raised but in RDR there is only 0. The following iterations are resulting always in a timeout (from IRDA_WaitOnFlagUntilTimeout()). I have no idea where to look... The pulses I receive are bigger than the 3/16 of a period, the levels are ok but seem I cannot get the message through the SIR receive decoder and in the data register.

I attach a screenshot with the received signal: IrDA_RX. Baud rate is fine, start and stop bits are present and the message (9 bits) is what I am waiting for. But is not recognized by the decoder and passed to the UART.