Posted on March 16, 2018 at 12:10Hi
I am still learning on the STM32, and currently working on the Nucleo-64 (STM32L073RZT6) board. I am currently trying to get the SPI to work, I am simply trying to send a byte out so I can capture it on my logic analyser to confirm its sending, just to confirm I have it correct, then can move onto proer communication with it. I am using SPI1, with pins PA5-CLK PA6-MISO PA7-MOSI PA8-CS. I have an SPI memory chip connected to these pins, which I use on another processor so I have used it for many years. My code is below, on my logic analyser I see the chip select drop , but there is nothing else, all other pins are low. Im not worried about timing at the moment, just want to see the output first...
Mnay thanks
Scott
void SPI()
{
RCC->IOPENR |= RCC_IOPENR_GPIOAEN;//enable GPIO port A clock
GPIOA->MODER &= ~GPIO_MODER_MODE8; //PA8 as output
GPIOA->MODER |= GPIO_MODER_MODE8_0;
GPIOA->BSRR |=GPIO_BSRR_BR_8;
GPIOA->BRR|=GPIO_BRR_BR_8;
GPIOA->ODR |= GPIO_ODR_OD8; //cs high
GPIOA->MODER &= ~GPIO_MODER_MODE5; //PA5 Alternate Function
GPIOA->MODER |= GPIO_MODER_MODE5_1;
GPIOA->MODER &= ~GPIO_MODER_MODE6; //PA6 Alternate Function
GPIOA->MODER |= GPIO_MODER_MODE6_1;
GPIOA->MODER &= ~GPIO_MODER_MODE7; //PA7 Alternate Function
GPIOA->MODER |= GPIO_MODER_MODE7_1;
//set alternate function AF0
GPIOB->AFR[1] &= ~GPIO_AFRL_AFRL5; //PA5-CLK
GPIOB->AFR[1] &= ~GPIO_AFRL_AFRL6; //PA6-MISO
GPIOB->AFR[1] &= ~GPIO_AFRL_AFRL7; //PA7-MOSI
RCC->APB2ENR |= RCC_APB2ENR_SPI1EN; //enable SPI1 clock
RCC->APB2RSTR |= RCC_APB2RSTR_SPI1RST; //reset SPI1
RCC->APB2RSTR &= ~RCC_APB2RSTR_SPI1RST; //reset SPI1
SPI1->CR1 &= ~SPI_CR1_SPE; //disable SPI
SPI1->CR1 &= ~SPI_CR1_RXONLY; //full duplex
SPI1->CR1 &= ~SPI_CR1_BIDIMODE; //bidirectional
SPI1->CR1 &= ~SPI_CR1_BIDIOE; //output disabled , received mode only
SPI1->CR1 &= ~SPI_CR1_DFF; //8 bit Data frame format
SPI1->CR1 &= ~SPI_CR1_LSBFIRST; //lsb first
SPI1->CR1 &= ~SPI_CR1_CPHA; //1st edge
SPI1->CR1 &= ~SPI_CR1_CPOL; //polarity low
SPI1->CR1 &= ~SPI_CR1_BR; //baud rate to clk/2
SPI1->CR1 &= ~SPI_CR1_CRCEN;//crc disabled
SPI1->CR2 &= ~SPI_CR2_FRF; //motorola mode
SPI1->CR1 |= SPI_CR1_MSTR; //set as master
SPI1->CR1 |= SPI_CR1_SPE; //enable SPI
unsigned char Tmp[5];Tmp[0]=0x55;
SPI_Write(&Tmp[0],1); //send 1 byte only....
}
void SPI_Write(unsigned char *txBuffer,int Size)
{
unsigned char dummy;
int i;
GPIOA->ODR &= ~GPIO_ODR_OD8; //cs low
for(i=0;i<Size;i++)
{
//wait for txe
while((SPI1->SR & SPI_SR_TXE) != SPI_SR_TXE);
SPI1->DR = txBuffer[i];
//wait for rxne
while((SPI1->SR & SPI_SR_RXNE) != SPI_SR_RXNE);
dummy=SPI1->DR;
}
//wait for BSY flag cleared
while((SPI1->SR & SPI_SR_BSY) != SPI_SR_BSY); //<<sticks here
//delay
GPIOA->ODR |= GPIO_ODR_OD8; //cs high
}
