树莓派3B验证SPI是否正常工作

用于测试树莓派的SPI接口是否正常工作，代码参考来自于

https://raw.githubusercontent.com/raspberrypi/linux/rpi-3.10.y/Documentation/spi/spidev_test.c

测试方法参考自：http://louisthiery.com/spi-Python-hardware-spi-for-raspi/

转载于：

http://blog.csdn.net/shenzhonglaoxu/article/details/44410985

代码:

/*  * SPI testing utility (using spidev driver)  *  * Copyright (c) 2007  MontaVista Software, Inc.  * Copyright (c) 2007  Anton Vorontsov <[e-mail]>  *  * This program is free software; you can redistribute it and/or modify  * it under the terms of the GNU General Public License as published by  * the Free Software Foundation; either version 2 of the License.  *  * Cross-compile with cross-gcc -I/path/to/cross-kernel/include  */    #include <stdint.h>  #include <unistd.h>  #include <stdio.h>  #include <stdlib.h>  #include <getopt.h>  #include <fcntl.h>  #include <sys/ioctl.h>  #include <linux/types.h>  #include <linux/spi/spidev.h>    #define ARRAY_SIZE(a) (sizeof(a)/sizeof((a)[0]))    static void pabort(const char *s)  {      perror(s);      abort();  }    static const char *device = "/dev/spidev0.1";  static uint8_t mode;  static uint8_t bits = 8;  static uint32_t speed = 500000;  static uint16_t delay;    static void transfer(int fd)  {  否则会出现以下结果：    int ret;      uint8_t tx[] = {          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,          0x40, 0x00, 0x00, 0x00, 0x00, 0x95,          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,          0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,          0xDE, 0xAD, 0xBE, 0xEF, 0xBA, 0xAD,          0xF0, 0x0D,      };      uint8_t rx[ARRAY_SIZE(tx)] = {0, };      struct spi_ioc_transfer tr = {          .tx_buf = (unsigned long)tx,          .rx_buf = (unsigned long)rx,          .len = ARRAY_SIZE(tx),          .delay_usecs = delay,          .speed_hz = speed,          .bits_per_word = bits,      };        ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);      if (ret < 1)          pabort("can't send spi message");        for (ret = 0; ret < ARRAY_SIZE(tx); ret++) {          if (!(ret % 6))              puts("");          printf("%.2X ", rx[ret]);      }      puts("");  }    static void print_usage(const char *prog)  {      printf("Usage: %s [-DsbdlHOLC3]\n", prog);      puts("  -D --device   device to use (default /dev/spidev1.1)\n"           "  -s --speed    max speed (Hz)\n"           "  -d --delay    delay (usec)\n"           "  -b --bpw      bits per word \n"           "  -l --loop     loopback\n"           "  -H --cpha     clock phase\n"           "  -O --cpol     clock polarity\n"           "  -L --lsb      least significant bit first\n"           "  -C --cs-high  chip select active high\n"           "  -3 --3wire    SI/SO signals shared\n");      exit(1);  }    static void parse_opts(int argc, char *argv[])  {      while (1)     {          static const struct option lopts[] = {              { "device",  1, 0, 'D' },              { "speed",   1, 0, 's' },              { "delay",   1, 0, 'd' },              { "bpw",     1, 0, 'b' },              { "loop",    0, 0, 'l' },              { "cpha",    0, 0, 'H' },              { "cpol",    0, 0, 'O' },              { "lsb",     0, 0, 'L' },              { "cs-high", 0, 0, 'C' },              { "3wire",   0, 0, '3' },              { "no-cs",   0, 0, 'N' },              { "ready",   0, 0, 'R' },              { NULL, 0, 0, 0 },          };                  int c;                  c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR", lopts, NULL);                  if (c == -1)              break;            switch (c) {          case 'D':              device = optarg;              break;          case 's':              speed = atoi(optarg);              break;          case 'd':              delay = atoi(optarg);              break;          case 'b':              bits = atoi(optarg);              break;          case 'l':              mode |= SPI_LOOP;              break;          case 'H':              mode |= SPI_CPHA;              break;          case 'O':              mode |= SPI_CPOL;              break;          case 'L':              mode |= SPI_LSB_FIRST;              break;          case 'C':              mode |= SPI_CS_HIGH;              break;          case '3':              mode |= SPI_3WIRE;              break;          case 'N':              mode |= SPI_NO_CS;              break;          case 'R':              mode |= SPI_READY;              break;          default:              print_usage(argv[0]);              break;          }      }  }    int main(int argc, char *argv[])  {      int ret = 0;      int fd;        parse_opts(argc, argv);        fd = open(device, O_RDWR);      if (fd < 0)          pabort("can't open device");        /*      * spi mode      */      ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);      if (ret == -1)          pabort("can't set spi mode");        ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);      if (ret == -1)          pabort("can't get spi mode");        /*      * bits per word      */      ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);      if (ret == -1)          pabort("can't set bits per word");        ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);      if (ret == -1)          pabort("can't get bits per word");        /*      * max speed hz      */      ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);      if (ret == -1)          pabort("can't set max speed hz");        ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);      if (ret == -1)          pabort("can't get max speed hz");        printf("spi mode: %d\n", mode);      printf("bits per word: %d\n", bits);      printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000);        transfer(fd);        close(fd);        return ret;  }  

1. 先用gcc编译

gcc spidev_test.c

得到一个a.out文件，后面会用到。

2. 将树莓派的MISO和MOSI引脚短接，运行命令

sudo modprobe spi_bcm2835

sudo ./a.out

如果SPI正常启用了的话，会出现以下结果：

否则会出现以下结果：