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SPI clock frequency in STM32F769NI Disco board
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2017-12-11 09:35 PM
Posted on December 12, 2017 at 06:35
how to configure for SPI clock frequency in SPI example provided.
Example give below i am using
In atmel board we are using 5mhz or 50khz SPI clock frequency.
int main(void)
{
/* Enable the CPU Cache */
CPU_CACHE_Enable();
HAL_Init();
/* Configure the system clock to 216 MHz */
SystemClock_Config();
/*##-1- Configure the SPI peripheral #######################################*/
/* Set the SPI parameters */
SpiHandle.Instance = SPIx;
SpiHandle.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_32;
SpiHandle.Init.Direction = SPI_DIRECTION_2LINES;
SpiHandle.Init.CLKPhase = SPI_PHASE_1EDGE;
SpiHandle.Init.CLKPolarity = SPI_POLARITY_LOW;
SpiHandle.Init.DataSize = SPI_DATASIZE_8BIT;
SpiHandle.Init.FirstBit = SPI_FIRSTBIT_MSB;
SpiHandle.Init.TIMode = SPI_TIMODE_DISABLE;
SpiHandle.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
SpiHandle.Init.CRCPolynomial = 7;
SpiHandle.Init.NSS = SPI_NSS_SOFT;
#ifdef MASTER_BOARD
SpiHandle.Init.Mode = SPI_MODE_MASTER;
#else
SpiHandle.Init.Mode = SPI_MODE_SLAVE;
HAL_Delay(5);
#endif /* MASTER_BOARD */
if(HAL_SPI_Init(&SpiHandle) != HAL_OK)
{
/* Initialization Error */
Error_Handler();
}
#ifdef MASTER_BOARD
/* Configure User push-button button */
BSP_PB_Init(BUTTON_USER,BUTTON_MODE_GPIO);
/* Wait for User push-button press before starting the Communication */
while (BSP_PB_GetState(BUTTON_USER) != GPIO_PIN_SET)
{
HAL_Delay(100);
}
#endif /* MASTER_BOARD */
/* Synchronization between Master and Slave */
Slave_Synchro();
}
#ifdef MASTER_BOARD
static void Master_Synchro(void)
{
uint8_t txackbytes = SPI_MASTER_SYNBYTE, rxackbytes = 0x00;
do
{
/* Call SPI write function to send command to slave */
if(HAL_SPI_TransmitReceive(&SpiHandle, (uint8_t *)&txackbytes, (uint8_t *)&rxackbytes, 1, HAL_MAX_DELAY) != HAL_OK)
{
Error_Handler();
}
}while(rxackbytes != SPI_SLAVE_SYNBYTE);
}
#else
static void Slave_Synchro(void)
{
uint8_t txackbyte = SPI_SLAVE_SYNBYTE, rxackbyte = 0x00;
// do
{
if (HAL_SPI_TransmitReceive(&SpiHandle, (uint8_t *)&txackbyte, (uint8_t *)&rxackbyte, 1, HAL_MAX_DELAY) != HAL_OK)
{
Error_Handler();
}
}
// while (rxackbyte != SPI_MASTER_SYNBYTE);
}
#endif
/**
* @brief System Clock Configuration
* The system Clock is configured as follow :
* System Clock source = PLL (HSE)
* SYSCLK(Hz) = 216000000
* HCLK(Hz) = 216000000
* AHB Prescaler = 1
* APB1 Prescaler = 4
* APB2 Prescaler = 2
* HSE Frequency(Hz) = 25000000
* PLL_M = 25
* PLL_N = 432
* PLL_P = 2
* PLL_Q = 9
* PLL_R = 7
* VDD(V) = 3.3
* Main regulator output voltage = Scale1 mode
* Flash Latency(WS) = 7
* @param None
* @retval None
*/
void SystemClock_Config(void)
{
RCC_ClkInitTypeDef RCC_ClkInitStruct;
RCC_OscInitTypeDef RCC_OscInitStruct;
HAL_StatusTypeDef ret = HAL_OK;
/* Enable HSE Oscillator and activate PLL with HSE as source */
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 25;
RCC_OscInitStruct.PLL.PLLN = 432;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 9;
RCC_OscInitStruct.PLL.PLLQ = 7;
ret = HAL_RCC_OscConfig(&RCC_OscInitStruct);
if(ret != HAL_OK)
{
while(1) { ; }
}
/* Activate the OverDrive to reach the 216 MHz Frequency */
ret = HAL_PWREx_EnableOverDrive();
if(ret != HAL_OK)
{
while(1) { ; }
}
/* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | 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;
ret = HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_7);
if(ret != HAL_OK)
{
while(1) { ; }
}
}
6 REPLIES 6
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2017-12-11 10:00 PM
Posted on December 12, 2017 at 07:00
You can set the spi baud rate prescaler
SpiHandle.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_32;
You can select the prescaler value according to the APB clock source for the SPI peripheral.
SPI 1,4,5,6 are connected to APB2 and 2,3 to APB1
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2017-12-11 11:07 PM
Posted on December 12, 2017 at 07:07
can you please tell me what is the baudrate need to keep for 50kHZ and 5Mhz according to you said.
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2017-12-11 11:29 PM
Posted on December 12, 2017 at 07:29
Since the baudrate prescaler can only be set to values of 2,4,8,16,32,64,128,256 You'd need to change the APB frequency as well.
For example, to get a 5Mhz SPI CLK, (For example for SPI 1/4/5/6) you need to set the APB2 clock to some value like 80MHz, and then use a prescaler of 16 and you get 80M/16 = 5MHz.
To change the APB2, its prescalar can also only take a limited number of values. So you might have to decrease the HCLK.
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2017-12-11 11:58 PM
Posted on December 12, 2017 at 07:58
where we need to change the
APB frequency,
for given below example,
/**
* @brief System Clock Configuration
* The system Clock is configured as follow :
* System Clock source = PLL (HSE)
* SYSCLK(Hz) = 216000000
* HCLK(Hz) = 216000000
* AHB Prescaler = 1
* APB1 Prescaler = 4
* APB2 Prescaler = 2
* HSE Frequency(Hz) = 25000000
* PLL_M = 25
* PLL_N = 432
* PLL_P = 2
* PLL_Q = 9
* PLL_R = 7
* VDD(V) = 3.3
* Main regulator output voltage = Scale1 mode
* Flash Latency(WS) = 7
* @param None
* @retval None
*/
void SystemClock_Config(void)
{
RCC_ClkInitTypeDef RCC_ClkInitStruct;
RCC_OscInitTypeDef RCC_OscInitStruct;
HAL_StatusTypeDef ret = HAL_OK;
/* Enable HSE Oscillator and activate PLL with HSE as source */
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = 25;
RCC_OscInitStruct.PLL.PLLN = 432;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 9;
RCC_OscInitStruct.PLL.PLLQ = 7;
ret = HAL_RCC_OscConfig(&RCC_OscInitStruct);
if(ret != HAL_OK)
{
while(1) { ; }
}
/* Activate the OverDrive to reach the 216 MHz Frequency */
ret = HAL_PWREx_EnableOverDrive();
if(ret != HAL_OK)
{
while(1) { ; }
}
/* Select PLL as system clock source and configure the HCLK, PCLK1 and PCLK2 clocks dividers */
RCC_ClkInitStruct.ClockType = (RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_HCLK | 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;
ret = HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_7);
if(ret != HAL_OK)
{
while(1) { ; }
}
}
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2017-12-12 01:38 AM
Posted on December 12, 2017 at 10:38
Modify
QSPIHandle.Init.ClockPrescaler = 1; /* QSPI SCLK freq = 216 MHz/(1+1) = 108 Mhz */
In function : uint8_t BSP_QSPI_Init(void)
It located at D:\STM32Cube_FW_F7_V1.6.0\Drivers\BSP\STM32F769I-Discovery\stm32f769i_discovery_qspi.c
MX25L512 can run SCLK up to 100MHz. Support DTR also.
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2017-12-12 03:10 AM
Posted on December 12, 2017 at 11:10
,
,
I am using SPI full duplex example not QSPI example
/* ♯ ♯ -1- Configure the SPI peripheral ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ ♯ */
, /* Set the SPI parameters */
, SpiHandle.Instance , , , , , , , , , , , , , , = SPIx,
, SpiHandle.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_32,
, SpiHandle.Init.Direction , , , , , , , , = SPI_DIRECTION_2LINES,
, SpiHandle.Init.CLKPhase , , , , , , , , , = SPI_PHASE_1EDGE,
, SpiHandle.Init.CLKPolarity , , , , , , = SPI_POLARITY_HIGH,
, SpiHandle.Init.DataSize , , , , , , , , , = SPI_DATASIZE_8BIT,
, SpiHandle.Init.FirstBit , , , , , , , , , = SPI_FIRSTBIT_MSB,
, SpiHandle.Init.TIMode , , , , , , , , , , , = SPI_TIMODE_DISABLE,
, SpiHandle.Init.CRCCalculation , , , = SPI_CRCCALCULATION_DISABLE,
, SpiHandle.Init.CRCPolynomial , , , , = 7,
, SpiHandle.Init.NSS , , , , , , , , , , , , , , = SPI_NSS_SOFT,
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