133 lines
2.6 KiB
C
133 lines
2.6 KiB
C
/* Raspberry Pi SPI */
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#include <stdio.h>
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#include <stdint.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <linux/types.h>
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#include <linux/spi/spidev.h>
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#include "spi.h"
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#define SPI_DEVICE "/dev/spidev0.0"
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/*
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* Pinout config for this example
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*
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* MOSI - GPIO 10 (physical pin 19)
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* MISO - GPIO 9 (physical pin 21)
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* SCLK - GPIO 11 (physical pin 23)
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* CE0 - GPIO 8 (physical pin 24)
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*
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*/
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#define SPI_MODE 0
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#define SPI_BITS 8
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#define SPI_SPEED 500 * 1000 /* 500 KHz */
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#define SPI_DELAY 0
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static int fd;
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int spi_init(void) {
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uint8_t mode = SPI_MODE;
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uint8_t bits = SPI_BITS;
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uint32_t speed = SPI_SPEED;
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if ((fd = open(SPI_DEVICE, O_RDWR)) < 0) {
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fprintf(stderr, "spi open(%s)\n", SPI_DEVICE);
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return 1;
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}
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if (ioctl(fd, SPI_IOC_RD_MODE, &mode) == -1) {
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fprintf(stderr, "SPI_IOC_RD_MODE\n");
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return 1;
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}
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if (ioctl(fd, SPI_IOC_WR_MODE, &mode) == -1) {
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fprintf(stderr, "SPI_IOC_WR_MODE\n");
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return 1;
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}
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if (ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits) == -1) {
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fprintf(stderr, "SPI_IOC_WR_BITS_PER_WORD\n");
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return 1;
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}
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if (ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits) == -1) {
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fprintf(stderr, "SPI_IOC_RD_BITS_PER_WORD\n");
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return 1;
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}
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if (ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed) == -1) {
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fprintf(stderr, "SPI_IOC_WR_MAX_SPEED_HZ\n");
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return 1;
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}
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if (ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed) == -1) {
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fprintf(stderr, "SPI_IOC_RD_MAX_SPEED_HZ\n");
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return 1;
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}
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return 0;
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}
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/* bme680 auto-increments for spi reads */
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int spi_read(uint8_t reg, uint8_t *dst, uint32_t size) {
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struct spi_ioc_transfer tr[2] = {0};
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reg |= 0x80;
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/* write first msg for the register addr */
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tr[0].tx_buf = (unsigned long) ®
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tr[0].rx_buf = (unsigned long) 0;
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tr[0].len = 1;
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/* write second msg for rx data */
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tr[1].tx_buf = (unsigned long) 0;
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tr[1].rx_buf = (unsigned long) dst;
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tr[1].len = size;
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if (ioctl(fd, SPI_IOC_MESSAGE(2), tr) < 0) {
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fprintf(stderr, "spi_read()\n");
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return 1;
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}
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return 0;
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}
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/* bme680 does NOT auto-increment for spi writes, so one at a time */
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int spi_write(uint8_t reg, uint8_t value) {
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struct spi_ioc_transfer tr[2] = {0};
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reg &= 0x7F;
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/* write first msg for the register addr */
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tr[0].tx_buf = (unsigned long) ®
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tr[0].rx_buf = (unsigned long) 0;
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tr[0].len = (uint32_t) 1;
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/* write second msg for the tx data */
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tr[1].tx_buf = (unsigned long) &value;
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tr[1].rx_buf = (unsigned long) 0;
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tr[1].len = (uint32_t) 1;
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if (ioctl(fd, SPI_IOC_MESSAGE(2), tr) < 0) {
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fprintf(stderr, "spi_write()\n");
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return 1;
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}
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return 0;
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}
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int spi_deinit(void) {
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if (fd) {
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close(fd);
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}
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return 0;
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}
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