STM32F407xx SPI Slave usage - Polling method.

[pradeepsysargus]

Posted on July 09, 2016 at 08:03

I am working on establishing SPI communication between STM32F407ZET6 and NRF52832 chipsets.

Currently, I am configuring STM32F407ZET6 is the slave as I need to send the data continuously from NRF52832.

I found code in github for configuring STM32F407xx as master, not as slave.

https://github.com/g4lvanix/STM32F4-examples/blob/master/SPI/main.c

The main function in this example continuously sends SPI data. In the same way, if you could show me how I can configure SPI slave and also continuously check for arrived data, it will be great. I am going to use polling method.

I know there is example code in spi standard peripheral drivers from ST that use interrupt method, but I am looking for polling method, that continuously check for arrived data.

Rgds,

[Tesla DeLorean]

Posted on July 09, 2016 at 15:54

uint8_t GetSPIByte(void)
{ 
/*!< Wait to receive a byte */
while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
/*!< Return the byte read from the SPI bus */
return SPI_I2S_ReceiveData(SPI1);
}

[pradeepsysargus]

Posted on July 10, 2016 at 01:30

Hello Clive1,

Thanks for the reply.

Please correct me if I am wrong. You did not include the slave configuration.

Please look into the configuration and also corresponding main function that I am writing for SPI slave:

// this function initializes the SPI1 peripheral

void init_SPI1(void){

GPIO_InitTypeDef GPIO_InitStruct;

SPI_InitTypeDef SPI_InitStruct;

// enable clock for used IO pins

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

/* configure pins used by SPI1

* PA5 = SCK

* PA6 = MISO

* PA7 = MOSI

*/

GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_6 | GPIO_Pin_5;

GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;

GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;

GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;

GPIO_Init(GPIOA, &GPIO_InitStruct);

// connect SPI1 pins to SPI alternate function

GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_SPI1);

GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_SPI1);

GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_SPI1);

// enable clock for used IO pins

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE, ENABLE);

/* Configure the chip select pin

in this case we will use PE7 */

GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7;

GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;

GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;

GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;

GPIO_Init(GPIOE, &GPIO_InitStruct);

GPIOE->BSRRL |= GPIO_Pin_7; // set PE7 high

// enable peripheral clock

RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);

/* configure SPI1 in Mode 0

* CPOL = 0 --> clock is low when idle

* CPHA = 0 --> data is sampled at the first edge

*/

SPI_InitStruct.SPI_Direction = SPI_Direction_2Lines_FullDuplex; // set to full duplex mode, seperate MOSI and MISO lines

SPI_InitStruct.SPI_Mode = SPI_Mode_Slave; // slave mode.

SPI_InitStruct.SPI_DataSize = SPI_DataSize_8b; // one packet of data is 8 bits wide

SPI_InitStruct.SPI_CPOL = SPI_CPOL_Low; // clock is low when idle

SPI_InitStruct.SPI_CPHA = SPI_CPHA_1Edge; // data sampled at first edge

SPI_InitStruct.SPI_NSS = SPI_NSS_Soft | SPI_NSSInternalSoft_Set; // set the NSS management to internal and pull internal NSS high

SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;// data is transmitted MSB first

SPI_Init(SPI1, &SPI_InitStruct);

SPI_Cmd(SPI1, ENABLE); // enable SPI1

}

int main(void){

uint8_t received_val = 0;

init_SPI1();

while(1){

   received_val = GetSPIByte(); // receive data

}

}

In the above code, PA5,PA6,PA7 are configured as sck, miso, mosi. PE7 as chip select.

These pins are same as used in the master code that was there in the link I sent.

I changed SPI_InitStruct.SPI_Mode = SPI_Mode_Master; to  SPI_InitStruct.SPI_Mode = SPI_Mode_Slave;  and commented out the line:

SPI_InitStruct.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_4;

I am thinking slave need not give the frequency to the master, which is why I commented out the line that give frequency. In the main function while loop, I am continuously checking for received data, should I give some delay here?

Thanks,

From: clive1

Posted: Saturday, July 09, 2016 3:54 PM

Subject: STM32F407xx SPI Slave usage - Polling method.

uint8_t GetSPIByte(void)

{

   /*!< Wait to receive a byte */

  while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);

 

  /*!< Return the byte read from the SPI bus */

  return SPI_I2S_ReceiveData(SPI1);

}

From: ch.pradeep

Posted: Saturday, July 09, 2016 8:03 AM

Subject: STM32F407xx SPI Slave usage - Polling method.

I am working on establishing SPI communication between STM32F407ZET6 and NRF52832 chipsets.

Currently, I am configuring STM32F407ZET6 is the slave as I need to send the data continuously from NRF52832.

I found code in github for configuring STM32F407xx as master, not as slave.

https://github.com/g4lvanix/STM32F4-examples/blob/master/SPI/main.c

The main function in this example continuously sends SPI data. In the same way, if you could show me how I can configure SPI slave and also continuously check for arrived data, it will be great. I am going to use polling method.

I know there is example code in spi standard peripheral drivers from ST that use interrupt method, but I am looking for polling method, that continuously check for arrived data.

Rgds,

[Tesla DeLorean]

Posted on July 10, 2016 at 15:33

The initialization for a Polling Slave should be nearly identical to that of an IRQ Slave.

I don't have any hardware set up to evaluate this, but there should be several slave examples within the SPL for EVAL or DISCO boards.

[pradeepsysargus]

Posted on August 08, 2016 at 14:56

Hello Clive1,

I am using the below SPI Slave configuration, Please look into it:

void init_SPI1(void){

GPIO_InitTypeDef GPIO_InitStruct;

SPI_InitTypeDef SPI_InitStruct;

// enable clock for used IO pins

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

/* configure pins used by SPI1

* PA5 = SCK

* PA6 = MISO

* PA7 = MOSI

*/

GPIO_InitStruct.GPIO_Pin = GPIO_Pin_7 | GPIO_Pin_6 | GPIO_Pin_5;

GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;

GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;

GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;

GPIO_Init(GPIOA, &GPIO_InitStruct);

// connect SPI1 pins to SPI alternate function

GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_SPI1);

GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_SPI1);

GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_SPI1);

// enable clock for used IO pins

//RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOE, ENABLE); COMMENT THIS LINE AS PORTE IS NOT NEEDED NOW

/* Configure the chip select pin

  in this case we will use PA4 */

GPIO_InitStruct.GPIO_Pin = GPIO_Pin_4;

GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN;

GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;

GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;

GPIO_Init(GPIOA, &GPIO_InitStruct);

// enable peripheral clock

RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE); // 84 Mhz

/* configure SPI1 in Mode 0 

* CPOL = 0 --> clock is low when idle

* CPHA = 0 --> data is sampled at the first edge

*/

SPI_InitStruct.SPI_Direction = SPI_Direction_2Lines_FullDuplex; // set to full duplex mode, seperate MOSI and MISO lines

SPI_InitStruct.SPI_Mode = SPI_Mode_Slave;     // transmit in slave mode, NSS pin has to be always high

SPI_InitStruct.SPI_DataSize = SPI_DataSize_8b; // one packet of data is 8 bits wide

SPI_InitStruct.SPI_CPOL = SPI_CPOL_Low;        // clock is low when idle

SPI_InitStruct.SPI_CPHA = SPI_CPHA_1Edge;      // data sampled at first edge

SPI_InitStruct.SPI_NSS = SPI_NSS_Soft | SPI_NSSInternalSoft_Set; // set the NSS management to internal and pull internal NSS high

SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;// data is transmitted MSB first

SPI_Init(SPI1, &SPI_InitStruct); 

SPI_Cmd(SPI1, ENABLE); // enable SPI1

}

uint8_t GetSPI1Byte(void)

{

   /*!< Wait to receive a byte */ 

 // while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);

  /*!< Return the byte read from the SPI bus */

  return SPI_I2S_ReceiveData(SPI1);

}

My main function is:

void main()

{

        init_SPI1();

uint8_t rcd_data = 0;

 

         while (1) 

{

if(!(GPIOA->IDR & 0x0010))

{

  rcd_data = GetSPI1Byte();

  printf(''Data Received: %x\r\n'',rcd_data);   

}

 

} // end of while loop

 }

As I said, I am trying to establish SPI communication between NRF52832 and STM32F407ZET6. 

I am able to see the clock and Chip select signals on the Oscilloscope from NRF chip. I checked that data is also sent from NRF chip. On slave side, the chipselect is going low, but a NULL(0x00) data is received all the time.

I configured Chip select as Input on Slave side. I am reading the Chipselect signal going low, and printing that value (NULL).

Can you please check my configuration and my main() code as well.?

Thanks,

Pradeep Ch.

[Tesla DeLorean]

Posted on August 08, 2016 at 18:21

Can you please check my configuration and my main() code as well?

I can only offer you a quick static analysis. Code looks to be reasonable. Make sure the data from the Master (it's Output) goes the the PA7 (the Slave's Input).

The cross-check would be to pull PA7 high and low and confirm 0xFF and 0x00 are observed.