Raspberry PI Model B+ (LCD显示CPU温度)

Title:Raspberry PI Model B+ (LCD显示CPU温度)  --2015-01-29 17:44

买了块连接Raspberry PI Model B+的LCD显示器，上面没写CPU温度，就加工了下。

修改后的pcd8544_rpi.c:

/*
=================================================================================
 Name        : pcd8544_rpi.c
 Version     : 0.1

 Copyright (C) 2012 by Andre Wussow, 2012, [email protected]

 Description :
     A simple PCD8544 LCD (Nokia3310/5110) for Raspberry Pi for displaying some system informations.
     Makes use of WiringPI-library of Gordon Henderson (https://projects.drogon.net/raspberry-pi/wiringpi/)

     Recommended connection (http://www.raspberrypi.org/archives/384):
     LCD pins      Raspberry Pi
     LCD1 - GND    P06  - GND
     LCD2 - VCC    P01 - 3.3V
     LCD3 - CLK    P11 - GPIO0
     LCD4 - Din    P12 - GPIO1
     LCD5 - D/C    P13 - GPIO2
     LCD6 - CS     P15 - GPIO3
     LCD7 - RST    P16 - GPIO4
     LCD8 - LED    P01 - 3.3V

================================================================================
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.
================================================================================
 */
#include <wiringPi.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/sysinfo.h>
#include "PCD8544.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define TEMP_FILE_PATH "/sys/class/thermal/thermal_zone0/temp"
#define MAX_SIZE 32 

// pin setup
int _din = 1;
int _sclk = 0;
int _dc = 2;
int _rst = 4;
int _cs = 3;

// lcd contrast
//may be need modify to fit your screen!  normal: 30- 90 ,default is:45 !!!maybe modify this value!
int contrast = 55; 

int main (void)
{
  // print infos
  printf("Raspberry Pi PCD8544 sysinfo display\n");
  printf("========================================\n");

  // check wiringPi setup
  if (wiringPiSetup() == -1)
  {
    printf("wiringPi-Error\n");
    exit(1);
  }

  // init and clear lcd
  LCDInit(_sclk, _din, _dc, _cs, _rst, contrast);
  LCDclear();

  // show logo
  LCDshowLogo();

  delay(2000);

  for (;;)
  {
      // clear lcd
      LCDclear();

      // get system usage / info
      struct sysinfo sys_info;
      if(sysinfo(&sys_info) != 0)
      {
        printf("sysinfo-Error\n");
      }

      // uptime
      char uptimeInfo[15];
      unsigned long uptime = sys_info.uptime / 60;
      sprintf(uptimeInfo, "Uptime %ld min.", uptime);

      // cpu info
      char cpuInfo[10];
      unsigned long avgCpuLoad = sys_info.loads[0] / 1000;
      sprintf(cpuInfo, "CPU %ld%%", avgCpuLoad);

      // ram info
      char ramInfo[10];
      unsigned long totalRam = sys_info.freeram / 1024 / 1024;
      sprintf(ramInfo, "RAM %ld MB", totalRam);

      // cpu Temperature
      char cputemperature[15];
      float cpu_temperature_Result = Get_Cpu_Temperature();
      sprintf(cputemperature, "TEMP %.2f ^C", cpu_temperature_Result);

      // build screen
      LCDdrawstring(0, 0, "Raspberry Pi:");
      LCDdrawline(0, 10, 83, 10, BLACK);
      LCDdrawstring(0, 12, uptimeInfo);
      LCDdrawstring(0, 20, cpuInfo);
      LCDdrawstring(0, 28, ramInfo);
      LCDdrawstring(0, 36, cputemperature);
      LCDdisplay();

      delay(1000);
  }

    //for (;;){
  //  printf("LED On\n");
  //  digitalWrite(pin, 1);
  //  delay(250);
  //  printf("LED Off\n");
  //  digitalWrite(pin, 0);
  //  delay(250);
  //}

  return 0;
}

int Get_Cpu_Temperature(void)
{
    int fd;
    double temp = 0;
    char buf[MAX_SIZE]; 

    // 打开/sys/class/thermal/thermal_zone0/temp
    fd = open(TEMP_FILE_PATH, O_RDONLY);
    if (fd < 0) {
        fprintf(stderr, "failed to open thermal_zone0/temp\n");
        return -1;
    } 

    // 读取内容
    if (read(fd, buf, MAX_SIZE) < 0) {
        fprintf(stderr, "failed to read temp\n");
        return -1;
    } 

    // 转换为浮点数打印
    temp = atoi(buf) / 1000.0; 

    // 关闭文件
    close(fd);
    return temp;
}

编译执行下：

cc -o cpushow pcd8544_rpi.c PCD8544.c  -L/usr/local/lib -lwiringPi

./cpushow

因为℃跟°C显示有问题，就用^代替那个点了。