Solved
SPI on STM32G031
I'm attempting to configure SPI1 on an STM32G031. However I must be missing something because there is no data being output. I am trying setup SPI to transmit 16 bits at a time. Any suggestions would be appreciated. I'm running the uC at 64Mhz.
// Configure PA4 as the SPI select pin
//-----------------------------------------------------------------------------
void spi::nss( ) {
GPIOA->MODER &= ~(GPIO_MODER_MODE4); // clear the mode bits for PA4
GPIOA->MODER |= GPIO_MODER_MODE4_0; // Set PA4 as output mode
GPIOA->OTYPER &= ~(GPIO_OTYPER_OT4); // Push-pull output on PA4
GPIOA->OSPEEDR |= GPIO_OSPEEDR_OSPEED4; // Set PA4 for High Speed
GPIOA->PUPDR &= ~(GPIO_PUPDR_PUPD4); // No pull-up/pull-down on PA4
}; // end css
// Configure pin PA5 as the SPI clock pin
//-----------------------------------------------------------------------------
void spi::sck( ) {
GPIOA->MODER &= ~(GPIO_MODER_MODE5); // clear the mode bits for PA5
GPIOA->MODER |= GPIO_MODER_MODE5_1; // Set PA5 to Alternate Function Mode
GPIOA->OTYPER &= ~(GPIO_OTYPER_OT5); // Push-pull output on PA5
GPIOA->OSPEEDR |= GPIO_OSPEEDR_OSPEED5; // Set speed of PA5 to Very High
GPIOA->AFR[ 0 ] &= ~(GPIO_AFRL_AFSEL5); // Set PA5 Alt Function to SPI1_SCK
}; // end clock
// Configure pin PA7 as the SPI Master-Out-Slave-In pin
//-----------------------------------------------------------------------------
void spi::mosi( ) {
GPIOA->MODER &= ~(GPIO_MODER_MODE7); // clear the mode bits for PA5
GPIOA->MODER |= GPIO_MODER_MODE7_1; // Set PA7 to Alternate Function Mode
GPIOA->OTYPER &= ~(GPIO_OTYPER_OT7); // Push-pull output on PA5
GPIOA->OSPEEDR |= GPIO_OSPEEDR_OSPEED7; // Set speed of PA5 to Very High
GPIOA->AFR[ 0 ] &= ~(GPIO_AFRL_AFSEL7); // Set PA7 Alt Function to SPI1_SCK
}; // end mosi
// Write 16 bits to SPI
//-----------------------------------------------------------------------------
void spi::write16( uint16_t data ) {
printf( "spi::write16 data: %lx\r\n", data );
select(); // NSS pin to low
while( !( SPI1->SR & SPI_SR_TXE ) ) __NOP();
*(volatile uint16_t*)&SPI1->DR = data;
while( SPI1->SR & SPI_SR_BSY ) __NOP();
deselect(); // NSS pin to high
}; // end write16
//-----------------------------------------------------------------------------
spi::spi( ) {
printf( "spi::spi\r\n" );
// Enable the RCC clocks for both GPIOA and SPI1
RCC->IOPENR |= RCC_IOPENR_GPIOAEN; // enable the GPIOA clock
RCC->APBENR2 |= RCC_APBENR2_SPI1EN; // enable the SPI1 clock
// GPIO settings
nss();
sck();
mosi();
// Configure SPI1
SPI1->CR1 &= SPI_CR1_SPE; // disable SPI1
SPI1->CR1 = 0; // clear out the cr1 register
SPI1->CR1 |= SPI_CR1_MSTR; // Master mode for SPI1
SPI1->CR1 |= SPI_CR1_SSM | SPI_CR1_MSTR | SPI_CR1_SSI;
SPI1->CR1 &= ~( SPI_CR1_CPOL | SPI_CR1_CPHA );
SPI1->CR1 &= ~SPI_CR1_LSBFIRST; // MSB first
SPI1->CR1 &= ~SPI_CR1_BR; // Clear BR bits
SPI1->CR1 |= ( SPI_CR1_BR_2 | SPI_CR1_BR_0 ); // 101 -> /64
SPI1->CR2 = 0; // clear cr2 register
SPI1->CR2 |= SPI_CR2_DS; // Set 16-bit data
SPI1->CR2 &= ~SPI_CR2_FRXTH; // RXNE set at 16-bits
SPI1->CR1 |= SPI_CR1_SPE; // enable SPI1
}; // end spi