Cannot get continuous data from SDADC

Perhaps I missed the USART stuff. The project is incomplete, and no point posting a copy of the unmodified example files. Find a better example for the task at hand.

If you want to capture wave forms you'd do much better using DMA to take periodic samples, not spin in a loop, somewhat asynchronously and post measurements to a slow serial connection.

You'd want a sample rate at least twice that of the wave form you're trying to capture to meet the Nyquist criterion

Tesla, Thank you for your reply!

Actually in the project, I create a global data array and put the array in the loop. During the loop, the data array will be updated every time after acquired a new value. I also add a timer to save the data every 100ms. The uart will transmit the saved data out when serial port receive a proper command byte.

​

As the original code is long and messy, I just collect some useful code here. Thanks for the help!

​

/* InjectedConvData contains the result of the conversion, updated in HAL_SDADC_InjectedConvCpltCallback*/
__IO int16_t InjectedConvData = 0;
 
/* Buffer used for reception */
uint8_t aRxCmd[RXCMDSIZE] = {0};
uint16_t aRxData[TXDATASIZE] = {0};
uint16_t data[TXDATASIZE + 1] = {0};
uint cnt_acq = 0;
uint cnt_data = 0; 
 
int main(void)
{
 __IO uint16_t newDigi = 0;
...................
...................
 
 while (endOfExample == 0)
 {
	/* Compute the input voltage */
	inputVoltageMv = (((InjectedConvData + 32768) * SDADC_VREF) / (SDADC_GAIN * SDADC_RESOL));
 
	/* Update new data to data array line */
	newDigi = 65536 * inputVoltageMv / 3300;
	if (cnt_data < TXDATASIZE)
	{
		aRxData[cnt_data] = newDigi;
	}
	else
	{
		cnt_data = 0;
	}
	cnt_data++;
 }
................
}
 
/**
 * @brief Injected conversion complete callback.
 * @param hsdadc : SDADC handle.
 * @retval None
 */
void HAL_SDADC_InjectedConvCpltCallback(SDADC_HandleTypeDef *hsdadc)
{
 /* Get conversion value */
 InjectedConvData = HAL_SDADC_InjectedGetValue(hsdadc, (uint32_t *) &InjChannel);
}
 
/**
 * @brief Period elapsed callback in non blocking mode
 * @param htim : TIM handle
 * @retval None
 */
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
	/* build data array line */
	int cnt;
	cnt = cnt_data - 1;
	if (cnt < 0) return;
 
	//rearrange data array line
	for (int i = cnt; i < TXDATASIZE; i++)
		data[i - cnt ] = aRxData[i];
	for (int j = 0; j < cnt; j++)
		data[TXDATASIZE - cnt + j] = aRxData[j];
}
 
/**
 * @brief Rx Transfer completed callback
 * @param huart: UART handle
 * @note This example shows a simple way to report end of DMA Rx transfer, and
 * you can add your own implementation.
 * @retval None
 */
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
 uint8_t SN[] = "***123456***";
 int cnt;
 switch(*aRxCmd)
 {
	case 0x96 : //Transmit data
	 	if (HAL_UART_Transmit(&UartHandle, (uint8_t*)data, TXDATASIZE, 500)!= HAL_OK)
	 	{
	 		Error_Handler();
	 	}
	 	break;
 
	default : //Return hex back if the received cmd is invalid
		if(HAL_UART_Transmit_DMA(&UartHandle, (uint8_t*)aRxCmd, RXCMDSIZE)!= HAL_OK)
		{
			Error_Handler();
		}
		break;
 }
 
 if (HAL_UART_Receive_DMA(&UartHandle, (uint8_t *)aRxCmd, RXCMDSIZE) != HAL_OK)
 {
	/* Transfer error in reception process */
	Error_Handler();
 }
}

Up to here, i just realized probably the global data array cannot save the real updated number as the loop runs too much faster...??? How do u think? Thanks!

​Kevin