Posted on July 27, 2015 at 22:40I'm pretty sure I'm doing all that. Still no recognizable clock signal either from the PB13 pin or from pin 6 of CN1 (the NFC connector). I'm trying to interface to an ST MKI/160V1 accelerometer eval board, but if I can't even get a clock signal...
Below is my code in its entirety. I've tried adding pin 12 (which I don't need, and didn't make a difference), I've tried witching to the HSI clock (because the Snippets example used that)--made no difference. I get nothing but a nice level 0V on the scope, and waiting for TXE times out.
(BTW, I'm using an open-source library whose register names might not be exactly the same as yours, but nothing unrecognizable, and I did check the addresses and such).
<code>
int spi_setup(void) {
RCC->IOPENR |= (RCC_IOPENR_IOPAEN | RCC_IOPENR_IOPBEN);
RCC->APB1ENR |= RCC_APB1ENR_SPI2EN;
// Set up B13..B15 for SPI2 (AF 0)
uint32_t v = GPIOB->MODER;
v &= ~(MASK_GPIO_MODER_MODE13 | MASK_GPIO_MODER_MODE14 | MASK_GPIO_MODER_MODE15);
v |= ((2 << SHIFT_GPIO_MODER_MODE13) | (2 << SHIFT_GPIO_MODER_MODE14) | (2 << SHIFT_GPIO_MODER_MODE15));
GPIOB->MODER = v;
v = GPIOB->AFR[1];
v &= ~(MASK_GPIO_AFRH_AFSEL13 | MASK_GPIO_AFRH_AFSEL14 | MASK_GPIO_AFRH_AFSEL15);
GPIOB->AFR[1] = v;
// Set up GPIO A8 as chip select
v = GPIOA->MODER;
v &= ~MASK_GPIO_MODER_MODE8;
v |= (1 << SHIFT_GPIO_MODER_MODE8);
GPIOA->MODER = v;
GPIOA->BSRR = GPIO_BSRR_BS8;
int rate = 3;
SPI2->CR1 = (SPI_CR1_SSM | SPI_CR1_MSTR | (rate << SHIFT_SPI_CR1_BR));
SPI2->CR2 = 0;
SPI2->CR1 |= SPI_CR1_SPE;
return 0;
}
</code>
