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raspberryPi3で温度測定

2016-10-17 18:07:32 | raspberry ...

raspberry Pi 3に熱電対式の温度計を接続して温度を測定するプログラムです。 熱電対温度計にはMAX31855を使用したＫ型熱電対アンプモジュールを用いました。


回路図

回路図はFritzingを使い描きました。

プログラム(C言語)

  1. #include <stdint.h>
  2. #include <unistd.h>
  3. #include <stdio.h>
  4. #include <stdlib.h>
  5. #include <getopt.h>
  6. #include <fcntl.h>
  7. #include <sys/ioctl.h>
  8. #include <linux/types.h>
  9. #include <linux/spi/spidev.h>
  11. #define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
  13. static void pabort(const char *s)
  14. {
  15.     perror(s);
  16.     abort();
  17. }
  19. static const char *device = "/dev/spidev0.0";
  20. static uint8_t mode;
  21. static uint8_t bits = 8;
  22. static uint32_t speed = 500000;
  23. static uint16_t delay;
  25. static void transfer(int fd)
  26. {
  27.     int ret;
  28.     unsigned tmp = 0;
  29.     double x;
  30.     uint8_t tx[] = {
  31.         0xFF, 0xFF, 0xFF, 0xFF
  32.     };
  33.     uint8_t rx[ARRAY_SIZE(tx)] = {0, };
  34.     struct spi_ioc_transfer tr = {
  35.         .tx_buf = (unsigned long)tx,
  36.         .rx_buf = (unsigned long)rx,
  37.         .len = ARRAY_SIZE(tx),
  38.         .delay_usecs = delay,
  39.         .speed_hz = speed,
  40.         .bits_per_word = bits,
  41.     };
  43.     ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
  44.     if (ret
  45.         pabort("can't send spi message");
  47.     if(rx[3]&0x01) printf("断線\n");
  48.     if(rx[3]&0x02) printf("GNDにショート\n");
  49.     if(rx[3]&0x04) printf("VCCにショート\n");
  51.     tmp = (rx[2] << 4) | (rx[3] >> 4);
  52.     if(tmp&0x800) {
  53.         tmp = (~tmp + 1) & 0x7FF;
  54.         x = (double)tmp*(-0.0625);
  55.     } else {
  56.         x = (double)tmp * 0.0625;
  57.     }
  58.     printf("現在の室温　%lf\n",x);
  60.       tmp = (rx[0] << 8) | (rx[1]);
  61.     tmp = tmp >> 2;
  62.     if(tmp&0x2000) {
  63.         tmp = (~tmp + 1) & 0x1FFF;
  64.         x = (double)tmp*(-0.25);
  65.     } else {
  66.         x = (double)tmp * 0.25;
  67.     }
  68.     printf("現在の熱電対の温度　%lf\n",x);
  69. }
  72. int main(int argc, char *argv[])
  73. {
  74.     int ret = 0;
  75.     int fd;
  77.     fd = open(device, O_RDWR);
  78.     if (fd < 0)
  79.         pabort("can't open device");
  81.     /*
  82.      * spi mode
  83.      */
  84.     ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
  85.     if (ret == -1)
  86.         pabort("can't set spi mode");
  88.     ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);
  89.     if (ret == -1)
  90.         pabort("can't get spi mode");
  92.     /*
  93.      * bits per word
  94.      */
  95.     ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
  96.     if (ret == -1)
  97.         pabort("can't set bits per word");
  99.     ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
  100.     if (ret == -1)
  101.         pabort("can't get bits per word");
  103.     /*
  104.      * max speed hz
  105.      */
  106.     ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
  107.     if (ret == -1)
  108.         pabort("can't set max speed hz");
  110.     ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);
  111.     if (ret == -1)
  112.         pabort("can't get max speed hz");
  114.     printf("spi mode: %d\n", mode);
  115.     printf("bits per word: %d\n", bits);
  116.     printf("max speed: %d Hz (%d KHz)\n\n", speed, speed/1000);
  118.     transfer(fd);
  120.     close(fd);
  122.     return ret;
  123. }


プログラムはSPIのサンプルコードを書き換えたものです。

プログラム(JavaScript)
SPIモジュールをインストールします。

  1.  $ npm install pi-spi


  1. var SPI = require('pi-spi');
  3. var spi = SPI.initialize("/dev/spidev0.0"),
  4.     test = Buffer("Hello, World!");
  5. var msg = Buffer("");
  7. // reads and writes simultaneously
  8. spi.read(4,function(e,d) {
  9.     if (e) console.error(e);
  10.     else {
  11. //--------------------
  12.     var tmp,x;
  13.     if(d[3]&0x01) console.log("断線\n");
  14.     if(d[3]&0x02) console.log("GNDにショート\n");
  15.     if(d[3]&0x04) console.log("VCCにショート\n");
  17.     tmp = (d[2] << 4) | (d[3] >> 4);
  18.     if( (tmp&0x800) != 0 ) {
  19.         tmp = (~tmp + 1) & 0x7FF;
  20.         x = tmp*(-0.0625);
  21.     } else {
  22.         x = tmp * 0.0625;
  23.     }
  24.     console.log("現在の室温　"+ x);
  27.       tmp = (d[0] << 8) | (d[1]);
  28.     tmp = tmp >> 2;
  29.     if((tmp&0x2000) != 0 ) {
  30.         tmp = (~tmp + 1) & 0x1FFF;
  31.         x = tmp*(-0.25);
  32.     } else {
  33.         x = tmp * 0.25;
  34.     }
  35.     console.log("現在の熱電対の温度　"+ x);
  37. //--------------------
  38.     }
  40. });