Good day,
I'm trying to control this RGB leds N-PI55TAT
Datasheet
I'm using an STM32H753VIT6
To do that I have to create a fairly fast burst of data with pulses of 0.6, 0.3 and 0.9 us.
To achieve this I set timer 7 to have an update even every 100nS then I set DMA2 stream 0 in memory to peripheral configuration.
The idea is to create a buffer, with the signal timing, and then set the DMA2 to transfer that buffer to the BSRR register of the port I have connected to the leds.
And it works, It generates the pulses every 100nS and then writting to the buffer where the sets and resets are I got my signal with pretty ok timing.
The problem is that it only works once.
Since I won't be updating the leds often, I don't want to create a circular buffer and load the DMA all the time. That's why I wanted to do a normal buffer, execute it once and execute it again when I need to change the colors.
While loop:
while (1)
{
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
iled_rst(); //Just a 200us low to reset the led
HAL_DMA_Start(&hdma_tim7_up, (uint32_t)bf, (uint32_t)&(GPIOE->BSRR), 289); //transfer buffer to BSRR
TIM7->DIER |= (1<<8); //I don't know what this is, but I read it's necesary
HAL_Delay(10); //10 ms is more than enough for the DMA to finish, the whole transfer takes about 20us
}
Buffer:
uint32_t bf[289] = {0};
//the buffer is then loaded with the corresponding data to time the signal
Init:
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_DMA_Init();
MX_SPI1_Init();
MX_USART3_UART_Init();
MX_USART2_UART_Init();
MX_I2C3_Init();
MX_USART1_UART_Init();
MX_TIM7_Init();
MX_TIM6_Init();
/* USER CODE BEGIN 2 */
HAL_TIM_Base_Start(&htim6);
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
HAL_TIM_Base_Start(&htim7);
If I put an interrupt before the while loop and set the logic analyzer to trigger, I get the signal sent once, perfectly done. But if I set the analyzer to trigger again the DMA just won't send the data anymore.
I tried clearing the interrupt flags of the DMA:
DMA2->HIFCR = 0x0FFFFFFF;
DMA2->LIFCR = 0x0FFFFFFF;
I read the status of DMA2 after the 10ms time
HAL_DMA_GetState(&hdma_tim7_up);
And its 2 HAL_DMA_STATE_BUSY = 0x02U, /*!< DMA process is ongoing */
I tried aborting after the 10ms
HAL_DMA_Abort(&hdma_tim7_up);
With no success.
Can you please explain to me why the DMA only transmits once?
Thank you very much
