How to config multi slave using SPI in STM32?

[HAlau.1]

Hello I'm try to connect 1 master and 2 slave, but failed, I use stm32f427VI, and use Truestudio for programing, thanks for your help.

/* SPI4 init function */ //SLAVE1
static void MX_SPI4_Init(void)
{
 
 /* SPI4 parameter configuration*/
 hspi4.Instance = SPI4;
 hspi4.Init.Mode = SPI_MODE_SLAVE;
 hspi4.Init.Direction = SPI_DIRECTION_2LINES;
 hspi4.Init.DataSize = SPI_DATASIZE_8BIT;
 hspi4.Init.CLKPolarity = SPI_POLARITY_LOW;
 hspi4.Init.CLKPhase = SPI_PHASE_2EDGE;
 hspi4.Init.NSS = SPI_NSS_SOFT;
 hspi4.Init.FirstBit = SPI_FIRSTBIT_MSB;
 hspi4.Init.TIMode = SPI_TIMODE_DISABLE;
 hspi4.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
 hspi4.Init.CRCPolynomial = 10;
 if (HAL_SPI_Init(&hspi4) != HAL_OK)
 {
 _Error_Handler(__FILE__, __LINE__);
 }
 
}

/* SPI4 init function */ //SLAVE2
static void MX_SPI4_Init(void)
{
 
 /* SPI4 parameter configuration*/
 hspi4.Instance = SPI4;
 hspi4.Init.Mode = SPI_MODE_SLAVE;
 hspi4.Init.Direction = SPI_DIRECTION_2LINES;
 hspi4.Init.DataSize = SPI_DATASIZE_8BIT;
 hspi4.Init.CLKPolarity = SPI_POLARITY_LOW;
 hspi4.Init.CLKPhase = SPI_PHASE_2EDGE;
 hspi4.Init.NSS = SPI_NSS_SOFT;
 hspi4.Init.FirstBit = SPI_FIRSTBIT_MSB;
 hspi4.Init.TIMode = SPI_TIMODE_DISABLE;
 hspi4.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
 hspi4.Init.CRCPolynomial = 10;
 if (HAL_SPI_Init(&hspi4) != HAL_OK)
 {
 _Error_Handler(__FILE__, __LINE__);
 }
 
}

/* SPI1 init function */ //MASTER
static void MX_SPI1_Init(void)
{
 
 /* 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_2EDGE;
 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(__FILE__, __LINE__);
 {
 asm("bkpt 255");
 }
 }
 
}

/* Includes --------------------Receive from slave2----------------------------------------*/
	 __HAL_SPI_ENABLE(&hspi1);
	 HAL_GPIO_WritePin(GPIOE, GPIO_PIN_8,GPIO_PIN_RESET);
	 HAL_SPI_Receive (&hspi1, outputBuffer2, 6, 50);
	 HAL_GPIO_WritePin(GPIOE, GPIO_PIN_8,GPIO_PIN_SET);
	 STM_Serial_Print("|");
	 STM_Serial_Print(outputBuffer2);
	 STM_Serial_Print("\r\n");
	 HAL_Delay(1000);
	 STM_Serial_Print("|");
	 STM_Serial_Print("data slave2");
	 STM_Serial_Print("\r\n");
	 HAL_Delay(1000);
/* Includes --------------------Receive from slave1----------------------------------------*/
	 __HAL_SPI_ENABLE(&hspi1);
	 HAL_GPIO_WritePin(GPIOE, GPIO_PIN_7,GPIO_PIN_RESET);
	 HAL_SPI_Receive (&hspi1, outputBuffer, 6, 50);
	 HAL_GPIO_WritePin(GPIOE, GPIO_PIN_7,GPIO_PIN_SET);
	 STM_Serial_Print("|");
	 STM_Serial_Print(outputBuffer);
	 STM_Serial_Print("\r\n");
	 HAL_Delay(1000);
	 STM_Serial_Print("|");
	 STM_Serial_Print("data slave1");
	 STM_Serial_Print("\r\n");
	 HAL_Delay(1000);

[KnarfB]

Don't see an error in your setup. How is your wiring? Star-topology? What are the GPIOs you are toggling?

[HAlau.1]

thank you, yes i use star wiring, i try to transmit character from slave but master only reads slave 1 and slave 2 unreadable

[HAlau.1]

can you tell me the problem and are there any suggestions?

[KnarfB]

How do you select a slave?

[HAlau.1]

by setting the pin as output and connecting to the ss pin on the master

[HAlau.1]

hou about vcc and gnd? does it need to be connected to the same source?

[KnarfB]

gnd: yes. Don't tie several vcc supplies together, vcc can be local to each board.

[HAlau.1]

ok thank you, Does it mean I can't use the same battery source for every board?

[KnarfB]

The same source for several boards is fine.

[HAlau.1]

thank you, I tried it but it still hasn't worked

[S.Ma]

All devices should use same digital output voltages as SPI is push pull type.

Master use SW NSS and you can use any 2 GPIO for NSS1 and NSS2

Slaves should use HW NSS to make sure their outputs automatically disable themselves when not selected. (otherwise, both slaves will talk simultaneously)

Create an EXTI interrupt on slaves' NSS pin (yes you can even if it maynot be a HAL or LL function) to get event when the comm just started or has just finished.

The Cube examples shows the peripheral is working, not how to use it in a typical application.

Note: If the bitrate is above 2MHz and packet size can be over 256, you could use DMA with cyclic buffer (no interrupt) on the slave side, and regular DMA for master side (interrupt when communication is complete).

For master, the communication completion and events should be on the reception complete, not the transmission.

[HAlau.1]

thank you, I new for this, what do you mean SW NSS, HW NSS and how to use it in program?

and how to make interrupt on the slave whether by making the SS slave pin which was previously only GPIO output becomes EXTI?