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F4 and F7 SPI CLK waveform

Forum|Forum|5 years ago
October 8, 2020
7 replies
2042 views

During testing an SPI DAC (TI DAC8563) on an STM32F446RE (where it works) and on an STM32F767ZI (where output is always 0V), I noticed a different SPI clock waveform.

In F4 you have three "8 pulses" signals from CLK (the message from MOSI is 24 bit), while in F7 you can read a single 24-pulse signal on CLK. The two programs are quite the same (generated by CubeIDE), so I suspect that the DAC8533 doesn't recognize the different words. The duration of signals are quite the same for the two MCU (10-15us)

This is the F4:

This is the F7:

Then I modified the F7 config to have the same SYNC Low timing (40us) but nothing changed.

Any idea?

Thanks very much,

Mario

This topic has been closed for replies.

Best answer by Lagodolio

SOLVED!!! The overcurrent LED sometimes glowed up... I supplied the DAC with an external supply and all works great!

I'm sorry for not realized it immediately, but my F7 is quite hidden and I thought that it was the ST-LINK LED.

TDK

There are no errors in the waveforms here. The delay between bytes is just to let the cpu catch up. It can be eliminated by using DMA or by better optimizing the code. The F7 SPI peripheral has a FIFO which can help to eliminate the delay.

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LagodolioAuthor

Associate III

Thanks for your answer. I thought that the F7 features "caused" the different behavior, but I'm no able to understand why the F4 works while the F7 doesn't. DAC8563 SPI can transmit data @ 50Mhz clock so it shouldn't have problems.

My configuration is "basic", no DMA or other optimization, just code from CubeIde with the same parameters for the two MCU...

TDK

Not real sure of why it's not working, but this isn't an apples to apples comparison. The SPI clock on the F4 is way faster than the SPI clock on the F7. Just eyeballing, it appears to be a factor of 4 or more faster. I would sort out that difference first.

"If you feel a post has answered your question, please click ""Accept as Solution""."

LagodolioAuthor

Associate III

I tried different combinations to slow down F7 (by prescaler and insertions of delays) because I thought the problem was SPI speed. My idea was to have a transmission time about 10-15us long (as the F4, that works) and a SYNC low 30-35 us. Unfortunately, I hadn't success so I thought that it was caused by an erroneous waveform in CLK (the most evident thing I noticed : for my mistake, I inserted in my question a graph with slowed parameters because I focused on clock signal...).

I can post my final programs: both the F4 and the F7 are set @168Mhz, 16 Prescaler (5.25Mbit/s), generated by CubeIDE 1.4.2. I removed the delays in the F7 code as they are unuseful. The F4 works, the F7 ....not.

LagodolioAuthor

Associate III

This is the F4 code (that works):

#include "main.h"
 
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
float calib=0.965;
/* USER CODE END Includes */
 
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
 
/* USER CODE END PTD */
 
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
 
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
 
/* USER CODE END PM */
 
/* Private variables ---------------------------------------------------------*/
SPI_HandleTypeDef hspi1;
 
/* USER CODE BEGIN PV */
 
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_SPI1_Init(void);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
 
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
 
 
/* USER CODE END 0 */
 
/**
 * @brief The application entry point.
 * @retval int
 */
int main(void)
{
 /* USER CODE BEGIN 1 */
 
 /* 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_SPI1_Init();
 /* USER CODE BEGIN 2 */
 /* USER CODE END 2 */
 
 /* Infinite loop */
 /* USER CODE BEGIN WHILE */
 
dac_reg_write(0x28, 0x0001); //reset DAC
dac_reg_write(0x20, 0x0003); //power_up DAC
dac_reg_write(0x38, 0x0001); //internal ref
dac_reg_write(0x02, 0x0000);//gain a x 2, b x 2
dac_reg_write(0x30, 0x0003); //deactivate load trigger
 
 //dac_reg_write(0x18, 32768); //center zero
//dac_reg_write(0x19,32768); //turn on internal ref
 
while (1)
 {
 /* USER CODE END WHILE */
 
 /* USER CODE BEGIN 3 */
	float voltage = 5.2;
 
	set_Voltage_A(voltage);
	dac_reg_write(0x19, 42768); //just to test B channel
 
 }
 /* USER CODE END 3 */
}
 
/**
 * @brief System Clock Configuration
 * @retval None
 */
void SystemClock_Config(void)
{
 RCC_OscInitTypeDef RCC_OscInitStruct = {0};
 RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
 /** Configure the main internal regulator output voltage
 */
 __HAL_RCC_PWR_CLK_ENABLE();
 __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
 /** Initializes the RCC Oscillators according to the specified parameters
 * in the RCC_OscInitTypeDef structure.
 */
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
 RCC_OscInitStruct.HSIState = RCC_HSI_ON;
 RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
 RCC_OscInitStruct.PLL.PLLM = 8;
 RCC_OscInitStruct.PLL.PLLN = 168;
 RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
 RCC_OscInitStruct.PLL.PLLQ = 2;
 RCC_OscInitStruct.PLL.PLLR = 2;
 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
 {
 Error_Handler();
 }
 /** Initializes the CPU, AHB and APB buses clocks
 */
 RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
 |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
 
 if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
 {
 Error_Handler();
 }
}
 
/**
 * @brief SPI1 Initialization Function
 * @param None
 * @retval None
 */
static void MX_SPI1_Init(void)
{
 
 /* USER CODE BEGIN SPI1_Init 0 */
 
 /* USER CODE END SPI1_Init 0 */
 
 /* USER CODE BEGIN SPI1_Init 1 */
 
 /* USER CODE END SPI1_Init 1 */
 /* SPI1 parameter configuration*/
 hspi1.Instance = SPI1;
 hspi1.Init.Mode = SPI_MODE_MASTER;
 hspi1.Init.Direction = SPI_DIRECTION_2LINES;
 hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
 hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;
 hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;
 hspi1.Init.NSS = SPI_NSS_SOFT;
 hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_16;
 hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;
 hspi1.Init.TIMode = SPI_TIMODE_DISABLE;
 hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
 hspi1.Init.CRCPolynomial = 10;
 if (HAL_SPI_Init(&hspi1) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN SPI1_Init 2 */
 
 /* USER CODE END SPI1_Init 2 */
 
}
 
/**
 * @brief GPIO Initialization Function
 * @param None
 * @retval None
 */
static void MX_GPIO_Init(void)
{
 GPIO_InitTypeDef GPIO_InitStruct = {0};
 
 /* GPIO Ports Clock Enable */
 __HAL_RCC_GPIOH_CLK_ENABLE();
 __HAL_RCC_GPIOA_CLK_ENABLE();
 __HAL_RCC_GPIOC_CLK_ENABLE();
 
 /*Configure GPIO pin Output Level */
 HAL_GPIO_WritePin(SYNC_GPIO_Port, SYNC_Pin, GPIO_PIN_RESET);
 
 /*Configure GPIO pin : SYNC_Pin */
 GPIO_InitStruct.Pin = SYNC_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 HAL_GPIO_Init(SYNC_GPIO_Port, &GPIO_InitStruct);
 
}
 
/* USER CODE BEGIN 4 */
void dac_reg_write(uint8_t command, uint16_t data)
{
 
	HAL_Delay(1);
 
	HAL_GPIO_WritePin(SYNC_GPIO_Port, SYNC_Pin, GPIO_PIN_RESET); //Sync Low
 
			// uint8_t value_bytes[2]={data,data >> 8};
	uint8_t value_bytes[2]={((data>>8) & 0xff),(data & 0xFF)}; // 16bit output value
	uint8_t mybytes[3] = { command, value_bytes[0] , value_bytes[1] };
 
		 if( HAL_SPI_Transmit(&hspi1, mybytes, 3, 0XFF)!= HAL_OK)
		 {
	 Error_Handler();
	 }
 
		HAL_GPIO_WritePin(SYNC_GPIO_Port, SYNC_Pin, GPIO_PIN_SET); //Sync High
}
void set_Voltage_A(float voltage_A)
{
	if (voltage_A<0)
	{
		voltage_A=0;
	}
	uint16_t data=32765+((uint16_t)((voltage_A/10)*(32765*calib)));
	dac_reg_write(0x18, data);
}
void set_Voltage_B(float voltage_B)
{
	if (voltage_B<0)
	{
		voltage_B=0;
	}
	uint16_t data=32765+((uint16_t)((voltage_B/10)*(32765*calib)));
	dac_reg_write(0x19, data);
}
/* USER CODE END 4 */
 
/**
 * @brief This function is executed in case of error occurrence.
 * @retval None
 */
void Error_Handler(void)
{
 /* USER CODE BEGIN Error_Handler_Debug */
 /* User can add his own implementation to report the HAL error return state */
 
 /* USER CODE END Error_Handler_Debug */
}
 
#ifdef USE_FULL_ASSERT
/**
 * @brief Reports the name of the source file and the source line number
 * where the assert_param error has occurred.
 * @param file: pointer to the source file name
 * @param line: assert_param error line source number
 * @retval None
 */
void assert_failed(uint8_t *file, uint32_t line)
{
 /* USER CODE BEGIN 6 */
 /* User can add his own implementation to report the file name and line number,
 tex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
 /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
 
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

LagodolioAuthor

Associate III

... and this is the F7 code (it doesn't work!)

#include "main.h"
 
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
float calib=0.965;
/* USER CODE END Includes */
 
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
 
/* USER CODE END PTD */
 
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
 
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
 
/* USER CODE END PM */
 
/* Private variables ---------------------------------------------------------*/
 
SPI_HandleTypeDef hspi4;
 
TIM_HandleTypeDef htim6;
 
/* USER CODE BEGIN PV */
 
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_SPI4_Init(void);
static void MX_TIM6_Init(void);
/* USER CODE BEGIN PFP */
 
/* USER CODE END PFP */
 
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
 
/* USER CODE END 0 */
 
/**
 * @brief The application entry point.
 * @retval int
 */
int main(void)
{
 /* USER CODE BEGIN 1 */
 
 /* 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_SPI4_Init();
 MX_TIM6_Init();
 /* USER CODE BEGIN 2 */
 dac_reg_write(0x28, 0x0001); //reset DAC
 dac_reg_write(0x20, 0x0003); //power_up DAC
 dac_reg_write(0x38, 0x0001); //internal ref
 dac_reg_write(0x02, 0x0000);//gain a x 2, b x 2
 dac_reg_write(0x30, 0x0003); //deactivate load trigger
 
 /* USER CODE END 2 */
 
 /* Infinite loop */
 /* USER CODE BEGIN WHILE */
 while (1)
 {
 /* USER CODE END WHILE */
 
 /* USER CODE BEGIN 3 */
	 float voltage = 5.2;
	 	set_Voltage_A(voltage);
	 	dac_reg_write(0x19, 42768);//just to test B channel
 }
 /* USER CODE END 3 */
}
 
/**
 * @brief System Clock Configuration
 * @retval None
 */
void SystemClock_Config(void)
{
 RCC_OscInitTypeDef RCC_OscInitStruct = {0};
 RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
 /** Configure the main internal regulator output voltage
 */
 __HAL_RCC_PWR_CLK_ENABLE();
 __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE2);
 /** Initializes the RCC Oscillators according to the specified parameters
 * in the RCC_OscInitTypeDef structure.
 */
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
 RCC_OscInitStruct.HSIState = RCC_HSI_ON;
 RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
 RCC_OscInitStruct.PLL.PLLM = 8;
 RCC_OscInitStruct.PLL.PLLN = 168;
 RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
 RCC_OscInitStruct.PLL.PLLQ = 2;
 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
 {
 Error_Handler();
 }
 /** Initializes the CPU, AHB and APB buses clocks
 */
 RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
 |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
 
 if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
 {
 Error_Handler();
 }
}
 
/**
 * @brief SPI4 Initialization Function
 * @param None
 * @retval None
 */
static void MX_SPI4_Init(void)
{
 
 /* USER CODE BEGIN SPI4_Init 0 */
 
 /* USER CODE END SPI4_Init 0 */
 
 /* USER CODE BEGIN SPI4_Init 1 */
 
 /* USER CODE END SPI4_Init 1 */
 /* SPI4 parameter configuration*/
 hspi4.Instance = SPI4;
 hspi4.Init.Mode = SPI_MODE_MASTER;
 hspi4.Init.Direction = SPI_DIRECTION_2LINES;
 hspi4.Init.DataSize = SPI_DATASIZE_8BIT;
 hspi4.Init.CLKPolarity = SPI_POLARITY_LOW;
 hspi4.Init.CLKPhase = SPI_PHASE_1EDGE;
 hspi4.Init.NSS = SPI_NSS_SOFT;
 hspi4.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_16;
 hspi4.Init.FirstBit = SPI_FIRSTBIT_MSB;
 hspi4.Init.TIMode = SPI_TIMODE_DISABLE;
 hspi4.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
 hspi4.Init.CRCPolynomial = 7;
 hspi4.Init.CRCLength = SPI_CRC_LENGTH_DATASIZE;
 hspi4.Init.NSSPMode = SPI_NSS_PULSE_DISABLE;
 if (HAL_SPI_Init(&hspi4) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN SPI4_Init 2 */
 
 /* USER CODE END SPI4_Init 2 */
 
}
 
/**
 * @brief TIM6 Initialization Function
 * @param None
 * @retval None
 */
static void MX_TIM6_Init(void)
{
 
 /* USER CODE BEGIN TIM6_Init 0 */
 
 /* USER CODE END TIM6_Init 0 */
 
 TIM_MasterConfigTypeDef sMasterConfig = {0};
 
 /* USER CODE BEGIN TIM6_Init 1 */
 
 /* USER CODE END TIM6_Init 1 */
 htim6.Instance = TIM6;
 htim6.Init.Prescaler = 0;
 htim6.Init.CounterMode = TIM_COUNTERMODE_UP;
 htim6.Init.Period = 65535;
 htim6.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
 if (HAL_TIM_Base_Init(&htim6) != HAL_OK)
 {
 Error_Handler();
 }
 sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
 sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
 if (HAL_TIMEx_MasterConfigSynchronization(&htim6, &sMasterConfig) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN TIM6_Init 2 */
 
 /* USER CODE END TIM6_Init 2 */
 
}
 
/**
 * @brief GPIO Initialization Function
 * @param None
 * @retval None
 */
static void MX_GPIO_Init(void)
{
 GPIO_InitTypeDef GPIO_InitStruct = {0};
 
 /* GPIO Ports Clock Enable */
 __HAL_RCC_GPIOE_CLK_ENABLE();
 __HAL_RCC_GPIOF_CLK_ENABLE();
 __HAL_RCC_GPIOH_CLK_ENABLE();
 
 /*Configure GPIO pin Output Level */
 HAL_GPIO_WritePin(SYNC_GPIO_Port, SYNC_Pin, GPIO_PIN_RESET);
 
 /*Configure GPIO pin : SYNC_Pin */
 GPIO_InitStruct.Pin = SYNC_Pin;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 HAL_GPIO_Init(SYNC_GPIO_Port, &GPIO_InitStruct);
 
}
 
/* USER CODE BEGIN 4 */
void dac_reg_write(uint8_t command, uint16_t data)
{
 
	HAL_Delay(1);
 
	HAL_GPIO_WritePin(SYNC_GPIO_Port, SYNC_Pin, GPIO_PIN_RESET); //Sync Low
 
	//	uint8_t value_bytes[2]={data,data >> 8};
	uint8_t value_bytes[2]={((data>>8) & 0xff),(data & 0xFF)}; // 16bit output value
	uint8_t mybytes[3] = { command, value_bytes[0] , value_bytes[1] };
		 if( HAL_SPI_Transmit(&hspi4, mybytes,3, 0XCC)!= HAL_OK)
		 {
	 Error_Handler();
	 }
 
		HAL_GPIO_WritePin(SYNC_GPIO_Port, SYNC_Pin, GPIO_PIN_SET); //Sync High
}
void set_Voltage_A(float voltage_A)
{
	if (voltage_A<0)
	{
		voltage_A=0;
	}
	uint16_t data=32765+((uint16_t)((voltage_A/10)*(32765*calib)));
	dac_reg_write(0x18, data);
}
void set_Voltage_B(float voltage_B)
{
	if (voltage_B<0)
	{
		voltage_B=0;
	}
	uint16_t data=32765+((uint16_t)((voltage_B/10)*(32765*calib)));
	dac_reg_write(0x19, data);
}
/* USER CODE END 4 */
 
/**
 * @brief This function is executed in case of error occurrence.
 * @retval None
 */
void Error_Handler(void)
{
 /* USER CODE BEGIN Error_Handler_Debug */
 /* User can add his own implementation to report the HAL error return state */
 
 /* USER CODE END Error_Handler_Debug */
}
 
#ifdef USE_FULL_ASSERT
/**
 * @brief Reports the name of the source file and the source line number
 * where the assert_param error has occurred.
 * @param file: pointer to the source file name
 * @param line: assert_param error line source number
 * @retval None
 */
void assert_failed(uint8_t *file, uint32_t line)
{
 /* USER CODE BEGIN 6 */
 /* User can add his own implementation to report the file name and line number,
 tex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
 /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
 
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

LagodolioAuthorBest answer

Associate III

SOLVED!!! The overcurrent LED sometimes glowed up... I supplied the DAC with an external supply and all works great!

I'm sorry for not realized it immediately, but my F7 is quite hidden and I thought that it was the ST-LINK LED.

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