Posted on January 29, 2018 at 14:48Hello,
I am trying to set up a project using an STM32F746ZG and an external DAC communicated by the SPI3. The idea is to transmit data from the MCU to the DAC periodically (using a timer and its interrupt) and use the callback function for SPI transfer complete to check whether the data transmission has ended. I need to send 16 bits data with MSB first.
To send the data I use a buffer which I need to acces each of the elements load in an array and transmit every uint16_t value over the SPI. I need to transmit one 16-bit value at a time (controlled by the timer).
Here is some code snippet so you can take a look,
const uint16_t aTxBuffer[32] = {2047, 1648, 1264, 910, 600, 345,
156, 39, 0, 39, 156, 345,
600, 910, 1264, 1648, 2048, 2447,
2831, 3185, 3495, 3750, 3939, 4056,
4095, 4056, 3939, 3750, 3495, 3185,
2831, 2447};
uint8_t cont = 0;
...
...
int main(){
...
...
...
while (1)
{
/* is it time to send data? */
if(flagStartSPI_DAC){
if(HAL_SPI_Transmit_IT(&hspi3, (uint8_t*)aTxBuffer[cont], 1) != HAL_OK){
_Error_Handler(__FILE__, __LINE__);
}
flagStartSPI_DAC = 0;
}
/* has the data been transmited over SPI yet? then start timer again */
if(flagStart_TIM){
flagStart_TIM = 0;
HAL_TIM_Base_Start_IT(&htim6);
}
}
}
...
...
...
void HAL_SPI_TxCpltCallback(SPI_HandleTypeDef* hspi){
cont++;
/* is it the last values in the array? */
if(cont==32){
cont = 0;
}
/* led on for debugging pourposes */
HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_7);
/* start timer */
flagStart_TIM = 1;
}
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef* htim){
/* time to send data over the SPI? */
if(htim->Instance == TIM6){
/* set the flag */
flagStartSPI_DAC = 1;
}
}
The problem I am experimenting now is that the SPI values I read using an logic analyzer are not correct and the SPI interrupt takes place only the first 8 timer triggers.
Anyone can help with this?
Thanks in advanced,
Omar
#stm32f-spi #interrupts #stm32f7
