spi.c

/***********************************************************************************
 * @file        spi.c                                                              *
 * @author      Matt Ricci                                                         *
 * @addtogroup  SPI                                                                *
 * @brief       Implements functions for SPI device interface initialization and   *
 *              communication.                                                     *
 *                                                                                 *
 * @todo        Rewrite initialisation to implement enum check for 8/16 bit mode   *
 *                          and assign approprriate function pointers                                                *
 ***********************************************************************************/
 
#include "spi.h"
 
static void SPI_send8(SPI *, uint16_t);
static void SPI_send16(SPI *, uint16_t);
 
static void SPI_receive8(SPI *, volatile uint16_t *);
static void SPI_receive16(SPI *, volatile uint16_t *);
 
/* =============================================================================== */
void SPI_init(SPI *spi, DeviceType device, SPI_TypeDef *interface, DataFormat df, GPIO_TypeDef *port, unsigned long cs) {
  spi->device    = device;
  spi->interface = interface;
  spi->port      = port;
  spi->cs        = cs;
 
  spi->send      = (df == MODE8) ? SPI_send8 : SPI_send16;
  spi->receive   = (df == MODE8) ? SPI_receive8 : SPI_receive16;
  spi->transmit  = SPI_transmit;
}
 
/* =============================================================================== */
uint16_t SPI_transmit(SPI *spi, uint16_t data) {
  volatile uint16_t response;
  spi->send(spi, data);
  spi->receive(spi, &response);
  while (spi->interface->SR & SPI_SR_BSY);
  return response;
}
 
/* =============================================================================== */
static void SPI_send8(SPI *spi, uint16_t data) {
  while (!(spi->interface->SR & SPI_SR_TXE));
  spi->interface->DR = (uint8_t)data;
}
 
static void SPI_send16(SPI *spi, uint16_t data) {
  while (!(spi->interface->SR & SPI_SR_TXE));
  spi->interface->DR = data;
}
 
/* =============================================================================== */
static void SPI_receive8(SPI *spi, volatile uint16_t *data) {
  while (!(spi->interface->SR & SPI_SR_RXNE));
  *data = (uint8_t) spi->interface->DR;
}
 
static void SPI_receive16(SPI *spi, volatile uint16_t *data) {
  while (!(spi->interface->SR & SPI_SR_RXNE));
  *data = spi->interface->DR;
}