I am having issues with my slave responding to my master. I am trying to lessen complexity by only using RXP on the slave, without TXP. The slave (Nucleo-H743ZI) responds one byte late.
On the CS interrupt I send 0 for the first byte and enable RXP.
*((__IO uint8_t *)&hspi1.Instance->TXDR) = 0;
__HAL_SPI_ENABLE_IT(&hspi1, SPI_IT_RXP);
__HAL_SPI_ENABLE(&hspi1);
I then receive a byte and set the next transmit byte. I use FPint so the master does not send data when it is low (used for later implementation).
void spiISRSTM(SPI_HandleTypeDef *hspi) {
//Receive if ready
if (hspi->Instance->SR & SPI_FLAG_RXP) {
HAL_GPIO_WritePin(nFPINT_GPIO_Port, nFPINT_Pin, GPIO_PIN_RESET);
rxBuffer = (*(__IO uint8_t *)&hspi->Instance->RXDR);
(*(__IO uint8_t *)&hspi->Instance->TXDR) = 1;
HAL_GPIO_WritePin(nFPINT_GPIO_Port, nFPINT_Pin, GPIO_PIN_SET);
}
__HAL_SPI_CLEAR_UDRFLAG(hspi);
__HAL_SPI_CLEAR_OVRFLAG(hspi);
__HAL_SPI_CLEAR_EOTFLAG(hspi);
__HAL_SPI_CLEAR_FREFLAG(hspi);
}
The MISO line for this setup is:
0011 1111
I would expect:
0111 1111
Any Ideas what is causing this?
