STM32H750 Discovery kit Clock Generation on GPIO Pin @ 10Mhz speed using DMA (Memory to peripheral copy).
Timer 5 is configured for 10 MHZ speed to trigger the DMA. In the DMA transfer (Memory to Peripheral) we are using the GPIO PB4 for clock generation. Clock is generated but it is not proper. We would like to the know the reason for it and any precautions/setting we have to follow to get the proper clock.
Source code main.c
int main(void)
{
/* USER CODE BEGIN 1 */
HAL_StatusTypeDef dataTransferStatus;
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_DMA_Init();
MX_TIM1_Init();
MX_USART1_UART_Init();
MX_TIM2_Init();
MX_TIM5_Init();
printf("entered into main\r\n");
//Timer Clock 240 MHZ .//Set 20 MHZ speed
htim5.Init.Prescaler=0;
htim5.Init.Period = 12-1;
//Enable timer
HAL_TIM_Base_Init(&htim5);
__HAL_TIM_ENABLE_DMA(&htim5, TIM_DMA_UPDATE);
__HAL_TIM_ENABLE(&htim5);
//loading GPIO high and low to DMA buffer
for(int i=0;i<32;i++)
{
if(i%2){
gpioFirstBuf[i] = (uint32_t)GPIOB->ODR | (1<<4) ; //1 -> pulls the line low
}
else{
gpioFirstBuf[i] = (uint32_t)GPIOB->ODR & ~(1<<4) ;
}
}
//Start DMA toggle GPIO -> PB4
dataTransferStatus = HAL_DMA_Start_IT(&hdma_tim5_up, (uint32_t)gpioFirstBuf, (uint32_t)&GPIOB->ODR, 24);
if(dataTransferStatus != HAL_OK){
HAL_DMA_Abort(&hdma_tim1_up);
}
/* USER CODE END 2 */
/* USER CODE BEGIN WHILE */
while (1)
{
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
}
/* USER CODE END 3 */
}Captured picture using CRO.
"Clock is not observed properly"
So observe it properly, then! ;p
Seriously,
- How, exactly, are you generating this?
- How, exactly, are you observing it?
- What are you seeing?
- What is "wrong" about what you are seeing?
It would help to see your code, and a 'scope trace of the output (if possible, get a screen capture - not a photo); maybe also a good, clear, in-focus photograph of your setup.
Is there a particular reason for using DMA rather than, say, a timer ... ?
