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.