Electrical – STM32F407ZET6 and nordic nrf24l01+ communication with interrupt driven SPI

interruptsmicrocontrollerspistm32stm32f4

Currently working on STM32F407ZET6 MCU. I am trying to generate an interrupt based SPI communication with nordic nrf24l01+ chipset. The MCU is in Master mode. I am able to establish an SPI communication but looks like it is using polling method.

I use the api uint8_t SPI1_send(uint8_t data) to send and receive data with SPI.

Need help with generating code for Interrupt driven SPI. If I use the interrupt driven SPI, do I still need to use the SPI1_send() API that I mentioned?

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 PE7 , NOW PA4 */
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_4;
    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(GPIOA, &GPIO_InitStruct);

    GPIOA->BSRRL |= GPIO_Pin_4; // set PE7 high; NOW PA4

    // 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_Master;     // transmit in master 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_BaudRatePrescaler = SPI_BaudRatePrescaler_4; // SPI frequency is APB2 frequency / 4 = 84Mhz/4 = 21Mhz 
    SPI_InitStruct.SPI_FirstBit = SPI_FirstBit_MSB;// data is transmitted MSB first
    SPI_Init(SPI1, &SPI_InitStruct); 

    SPI_Cmd(SPI1, ENABLE); // enable SPI1     
}

/* This funtion is used to transmit and receive data 
* with SPI1
*           data --> data to be transmitted
*           returns received value
*/
uint8_t SPI1_send(uint8_t data){

    SPI1->DR = data; // write data to be transmitted to the SPI data register
    while( !(SPI1->SR & SPI_I2S_FLAG_TXE) ); // wait until transmit complete
    while( !(SPI1->SR & SPI_I2S_FLAG_RXNE) ); // wait until receive complete
    while( SPI1->SR & SPI_I2S_FLAG_BSY ); // wait until SPI is not busy anymore
    return SPI1->DR; // return received data from SPI data register  
}

The above code is self explanatory, it has init SPI function and Send/Receive function. I can add how I call these functions in main() also. When I need to send or receive data through SPI to nordic chip, I use the function SPI1_send(). As I said, If I use interrupt mode, do I still need to use the function SPI1_send() as ISR will take care of sending/receiving I suppose.

Best Answer

The HAL provides this functionality.

You would call HAL_SPI_Transmit_IT with a pointer to the SPI structure, a pointer to the data buffer, and the size of the data buffer. This will send your whole buffer, interrupt style.

Obviously this requires you to include/switch over to the HAL, and configure and initialize it properly.

See ST User Manual UM1725 for a description of the HAL SPI library.