Hi all,
I am using the NUCLEO-F446RE with the STM32F446RE. I am trying to interface with an external dual sampling differential ADC: ADS9224R.
ADC Timing Diagram
I have been struggling to meet the timing that I require and can only reach ~180kHz with the STM32. My problem is that initiating separate SPI receive calls takes too long between commands.
Running the following code to initiate back to back SPI reads:
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_6, GPIO_PIN_RESET); //CS LOW
HAL_SPI_Receive(&hspi1, (uint8_t *)spi_buffer, 1,40);
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_6, GPIO_PIN_SET); //CS high
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_6, GPIO_PIN_RESET); //CS LOW
HAL_SPI_Receive(&hspi1, (uint8_t *)spi_buffer, 1,40);
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_6, GPIO_PIN_SET); //CS highProduces the following timing:
The STM32 is operating at 180MHz, and the SPI CLK is at ~30MHz. You can see that once the SPI initiates it is very fast, but the time to initiate the next SPI read is taking too long (~6us) which is limiting the rate at which I can read from the ADC.
I understand that this approach will only read ADC-0A, and not ADC-0B simultaneously. I have an implementation that uses QSPI but suffers from the same problem. I have simplified to single line SPI in hope that more people can provide help and I can transfer this to a dual line implementation.
Thank you all for your help!
Here are my settings and waveforms:
I've replicated this on my side now! The red and blue waveforms are the dual ADC outputs.
I'm going to try and implement the 2 slave SPI with DMA now! I'll let you know how I get on.
Thanks again.
Thanks, I will give that a try tomorrow when I have access to the oscilloscope, although I thought I had already tried that...
My SPI DMA receive callback does not seem to run. I am configuring a single SPI currently as shown below:
With the following code:
//before main:
uint16_t buffer[100];
__HAL_SPI_ENABLE(&hspi2);
HAL_SPI_Receive_DMA(&hspi2, (uint8_t *)&buffer, 1);
//after main:
void HAL_SPI_RxCpltCallback(SPI_HandleTypeDef * hspi)
{
int a; //BREAKPOINT HERE
}When running the code in debug mode with a breakpoint on line 9, I would expect the callback to run because data will be read by the slave SPI.
In hardware I have connected:
SPI2_SCLK -> Timer 1 pulse output
SPI2_INPUT -> ADC_output_A
Do I need to trigger the read of the SPI? Or should this happen automatically if it is fed the clock? Do I need to enable hardware NSS, and also connect the CS, I tried this but got the same result?
Thanks!
Hello ,
I am using stm32h7 and needs to read data from ads8661, I followed the above and managed to get the following graph. what I noticed is I also get the data value in the MISO line as shown.
GREEN is the CS pin connected to TIM2_CH1
BLUE is the MISO pin
when I configure the SPI as and how it is done above i.e Recieve only slave mode with DMA I am reading garbage values.
I used the following code
__HAL_SPI_ENABLE(&hspi2);
HAL_SPI_Receive_DMA(&hspi2, (uint8_t *)&buffer, 2);
HAL_TIM_PWM_Start(&htim1, TIM_CHANNEL_1);
HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_1);
while(1)
{
HAL_Delay(1000);
HAL_TIM_PWM_Stop(&htim1, TIM_CHANNEL_1);
HAL_TIM_PWM_Stop(&htim2, TIM_CHANNEL_1);
HAL_UART_Transmit(&huart3,"-------------------------------\n", 30, 10);
for(int i=0;i<100;i++)
{
sprintf(UART3_rxBuffer2,"=%05d\n",spibuffer[i]);
HAL_UART_Transmit(&huart3, UART3_rxBuffer2, 7, 10);
}
memset(buffer,0,99);
HAL_Delay(10);
HAL_TIM_PWM_Start(&htim1, TIM_CHANNEL_1);
HAL_TIM_PWM_Start(&htim2, TIM_CHANNEL_1);
}In hardware I have connected:
SPI2_SCLK -> Timer 1 ch 1
SPI2_INPUT -> MISO
screen shot of Garbage values printed on console
why the value read are garbage values ? shouldnt it be a constant according to the MISO line in the scope?
Thanks!
