TIMER

[DYann.1]

Hello,

I found an example on the internet of a project but I don't understand the usefulness of using a Timer 7. Could you tell me why ? Thanks in advance.

 

__IO uint32_t usTick;
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
 /* Prevent unused argument(s) compilation warning */
 if(htim==&htim7){
	usTick++;	
	}
 /* NOTE : This function Should not be modified, when the callback is needed,
 the __HAL_TIM_PeriodElapsedCallback could be implemented in the user file
 */
}

void delay_us(__IO uint32_t Delay){
uint32_t t=usTick;
uint32_t wait = Delay;
while( usTick - t < wait);

}
int main(void)
{

 /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
 HAL_Init();

 /* Configure the system clock */
 SystemClock_Config();

 /* Initialize all configured peripherals */
 MX_GPIO_Init();
 MX_TIM7_Init();
	/*if (HAL_TIM_Base_Start(&htim7) != HAL_OK) {
		 _Error_Handler(__FILE__, __LINE__);
 }*/
	if (HAL_TIM_Base_Start_IT(&htim7) != HAL_OK) {
		 _Error_Handler(__FILE__, __LINE__);
 }

 MX_I2C1_Init();
	 MX_I2S2_Init();

	HAL_Delay(100);

	audio.init();


	bool ptt=HAL_GPIO_ReadPin(GPIOE,PTT_SWITCH);
	bool pttstate=ptt;
	uint16_t index = 0;
	uint16_t buf = 0;
	audio.set_volume(0);
 /* Infinite loop */
 	while (1)//	read power switch
	{
		ptt=HAL_GPIO_ReadPin(GPIO_PINS,PTT_SWITCH);
		if(ptt!=pttstate){
			if(ptt==0){

				audio.start_receive();
				for(buf=0;buf<32;buf++){
					for(index=0;index < AUDIO_BUF_SIZE;index++){
						HAL_I2SEx_TransmitReceive(&hi2s2, &i2s_zero,&i2s_buf[buf][index], 1,0xFF);
					}
				}

				audio.start_play();
				for(buf=0;buf<32;buf++){
					for(index=0;index < AUDIO_BUF_SIZE;index++){
						HAL_I2SEx_TransmitReceive(&hi2s2, &i2s_buf[buf][index],&i2s_zero, 1,0xFF);
					}
				}
			}
			
			pttstate=ptt;
		}
 	}

}

 

 

[LCE]

> Of cours I'm a beginner... So you have a problem with theses people ?

Surely not, but most people here don't have the time to take you by the hand.
That's why I say, read the manual, check some tutorials, example code, etcpp...
It helps if there are at least some basics.
As AC/DC said, it's a long way to the top! ;)

The good thing: trial and error will (probably & hopefully) not kill your hardware.

[Pavel A.]

@DYann.1 Here is the official ST tutorial on the DMA :   https://wiki.st.com/stm32mcu/wiki/Getting_started_with_DMA

And there are so many folks ready to patiently help beginners .... they just expect something in return :) Care and share goes both ways.

 

ST official training on STM32L5: https://www.st.com/content/st_com/en/support/learning/stm32-education/stm32-online-training/stm32l5-online-training.html

Enjoy!

[DYann.1]

Thank you, I'll look at these 2 links.

[DYann.1]

Hi,

After reading the SAI and DMA documentation, I coded a piece of the program. I think I'm recovering data. Here is the code what do you think ? Thank you for your help.

 

int main(void)
{
 /* USER CODE BEGIN 1 */
	HAL_StatusTypeDef fresult;
	int32_t playbuf[4096*2] __attribute__ ((aligned (32)));
 /* 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();

/* Configure the peripherals common clocks */
 PeriphCommonClock_Config();

 /* USER CODE BEGIN SysInit */

 /* USER CODE END SysInit */

 /* Initialize all configured peripherals */
 MX_GPIO_Init();
 MX_DMA_Init();
 MX_SAI1_Init();
 MX_I2C1_Init();
 /* USER CODE BEGIN 2 */
 HAL_SAI_RegisterCallback(&hsai_BlockB1, HAL_SAI_TX_HALFCOMPLETE_CB_ID, HAL_SAI_TxHalfCpltCallback);
 HAL_SAI_RegisterCallback(&hsai_BlockB1, HAL_SAI_TX_COMPLETE_CB_ID, HAL_SAI_TxCpltCallback);
 fresult= HAL_SAI_Init(&hsai_BlockB1);
 if (fresult != HAL_OK)
	{
 	return HAL_ERROR;
	}
 fresult = HAL_SAI_Transmit_DMA(&hsai_BlockB1, (uint8_t *)playbuf , (sizeof(playbuf))/4);
 HAL_Delay(100);
 SGTL5000_init();
 set_volume(0);
 /* USER CODE END 2 */

 /* Infinite loop */
 /* USER CODE BEGIN WHILE */
 while (1)
 {
 /* USER CODE END WHILE */
	 start_receive();
	 HAL_Delay(100);
 /* USER CODE BEGIN 3 */
 }
 /* USER CODE END 3 */
}

Here is what I see in the table :

 

[Pavel A.]

The last image "Expressions" is indeed confusing. The values in the rightmost column are not values but addresses of 100-item slices of array playbuf.  If you expand any slice it will show the actual array elements.

This is how the Eclipse debugger behaves ((

[LCE]

For simple testing without the Codec, you could directly connect SAI data output to data input, then compare transmit buffer ("playbuf")  with the receive buffer.

Start with a simple signal in playbuf, like playbuf[i] = i; i++;

 

 

[DYann.1]

Hi,

It's a good idea but after my configuration :

Right for SAI data output to data input but what should I do for the other 3 connections ? Which are :

SAI1_MCLK_B (Master CLK)

SAI1_FS_B (Frame Synchro)

SAI1_SCK_B (Bit Clock).

I still let them connect to the CODEC, it seems to me, right ? In my case I just connect

SAI1_SD_B with SAI1_SD_A. Right ?  

[DYann.1]

After connecting SAI1_SD_B with SAI1_SD_A and do the for loop.

But now How to check if I have theses values via SAI1_SD_B ?

I wonder what is the meaning of 'Memory To Peripheral'. After me the DMA stores data in a device but what is this device? A user-defined memory area ?

[LCE]

The SAI blocks can be synchronized internally.

Connection: I mean a hardware connection from pin to pin, don't know if that is feasible on your board, there might be some soldering involved.

Memory: internal SRAM buffer, those you assign by calling the DMA start function

Peripheral: all that stuff not CPU or memory, like interfaces (in your case the SAI), ADC, DAC, Timers, ...

Data go this way:

• ext. ADC -> SAI RX -> DMA -> SRAM AD buffers
• SRAM DA buffers (your "playbuf") -> DMA -> SAI TX -> ext. DAC

[DYann.1]

Thank you for your helps, this information is very clear (for me) compared to the numerous videos or code examples that I have seen. No problem for the connection, I've the evaluation board STM32L5 and the CODEC so I use this jump between 2 connections  :

 

Sorry In my program I did not call the DMA Start function as you say. I configured the DMA in circular mode only :

I don't know if this is the right method but I have no errors when my program runs.

[DYann.1]

Here is my Main for this moment :

int main(void)
{
 /* USER CODE BEGIN 1 */
	HAL_StatusTypeDef fresult;
	int32_t playbuf[4096*2] __attribute__ ((aligned (32)));
 /* 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();

/* Configure the peripherals common clocks */
 PeriphCommonClock_Config();

 /* USER CODE BEGIN SysInit */

 /* USER CODE END SysInit */

 /* Initialize all configured peripherals */
 MX_GPIO_Init();
 MX_DMA_Init();
 MX_SAI1_Init();
 MX_I2C1_Init();
 /* USER CODE BEGIN 2 */
 HAL_SAI_RegisterCallback(&hsai_BlockB1, HAL_SAI_TX_HALFCOMPLETE_CB_ID, HAL_SAI_TxHalfCpltCallback);
 HAL_SAI_RegisterCallback(&hsai_BlockB1, HAL_SAI_TX_COMPLETE_CB_ID, HAL_SAI_TxCpltCallback);
 fresult= HAL_SAI_Init(&hsai_BlockB1);
 if (fresult != HAL_OK)
	{
 	return HAL_ERROR;
	}
 fresult = HAL_SAI_Transmit_DMA(&hsai_BlockB1, (uint8_t *)playbuf , (sizeof(playbuf))/4);
 HAL_Delay(100);
 SGTL5000_init();
 set_volume(0);
 /* USER CODE END 2 */

 /* Infinite loop */
 /* USER CODE BEGIN WHILE */
 while (1)
 {
 /* USER CODE END WHILE */
	 int32_t i;

	 for (i=0;i<100;i++)
	 {playbuf[i]=i;}
	 start_receive();
	 HAL_Delay(100);
 /* USER CODE BEGIN 3 */
 }
 /* USER CODE END 3 */
}

[LCE]

I'd rather fill the buffer once, before the while loop, and fill it completely.

[DYann.1]

Yes of course, you're right about this buffer. But I would like to have a little precision please. After your explanation

So when I fill the array (playbuf) with the values, I only check the way

SRAM DA buffer -> DMA -> SAI TX -> ext. DAC (not for me). In this case why to connect SAI1_SD_B with SAI1_SD_A ? Is this really necessary ?

I can't verify for the moment the way : ext.ADC -> SAI RX -> DMA -> SRAM AD buffers. Right ? 

[LCE]

What kind of of hardware do you actually have?

Is a Codec connected, and if yes, how?

How are the SAI blocks set up? Which is transmitter, which is receiver?

 

[DYann.1]

"What kind of of hardware do you actually have ?" 

I have a STM32L552E-EV evaluation board with audio board (CODEC SGTL5000, Audio Adaptor Rev D for Teensy 4.0).  

https://www.pjrc.com/store/teensy3_audio.html

"Is a Codec connected, and if yes, how?"

Yes the CODEC is connect to the STM32 and my configuration with the CODEC is :

According to my knowledge via the documentation

FSx - Frame Synchronisation

SCKx - bit Clock

SDx - Serial data line

MCLK - Master Clock

And for I2S LRCLK is equivalent FS for SAI.

"How are the SAI blocks set up?"

I have this configuration but I don't know if I answer your question ?

Which is transmitter, which is receiver?

The transmitter is SAI B and the receiver is SAI A (so CODEC is the slave after me). I hope I answered your questions.