SPI_FullDuplex_ComDMA_Master Example Description

Data buffer transmission/reception between two boards via SPI using DMA.

   Board: NUCLEO-C031C6 (embeds a STM32C031C6 device)
   - CLK Pin: PB3 (CN9, pin 4)
   - MISO Pin: PB4 (CN9, pin 6)
   - MOSI Pin: PB5 (CN9, pin 7)

HAL architecture allows user to easily change code to move to Polling or IT mode.

At the beginning of the main program the HAL_Init() function is called to reset all the peripherals, initialize the Flash interface and the systick. Then the SystemClock_Config() function is used to configure the system clock (SYSCLK) to run at 48 MHz.

The SPI peripheral configuration is ensured by the HAL_SPI_Init() function. This later is calling the HAL_SPI_MspInit()function which core is implementing the configuration of the needed SPI resources according to the used hardware (CLOCK, GPIO, DMA and NVIC). You may update this function to change SPI configuration.

The SPI communication is then initiated. The HAL_SPI_TransmitReceive_DMA() function allows the reception and the transmission of a predefined data buffer at the same time (Full Duplex Mode). If the Master board is used, the project SPI_FullDuplex_ComDMA_Master must be used. If the Slave board is used, the project SPI_FullDuplex_ComDMA_Slave must be used.

For this example the aTxBuffer is predefined and the aRxBuffer size is same as aTxBuffer.

In a first step after the user press the User push-button, SPI Master starts the communication by sending aTxBuffer and receiving aRxBuffer through HAL_SPI_TransmitReceive_DMA(), at the same time SPI Slave transmits aTxBuffer and receives aRxBuffer through HAL_SPI_TransmitReceive_DMA(). The callback functions (HAL_SPI_TxRxCpltCallback and HAL_SPI_ErrorCallbackand) update the variable wTransferState used in the main function to check the transfer status. Finally, aRxBuffer and aTxBuffer are compared through Buffercmp() in order to check buffers correctness.

STM32 board’s LEDs can be used to monitor the transfer status:

Notes

  1. You need to perform a reset on Slave board, then perform it on Master board to have the correct behaviour of this example.

  2. Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds) based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower) than the peripheral interrupt. Otherwise the caller ISR process will be blocked. To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.

  3. The application need to ensure that the SysTick time base is always set to 1 millisecond to have correct HAL operation.

Keywords

Connectivity, SPI, Full-duplex, Interrupt, Transmission, Reception, Master, Slave, MISO, MOSI, DMA

Directory contents

Hardware and Software environment

How to use it ?

In order to make the program work, you must do the following: