co2monitor_fltk.cc

// g++ -s -O2 -o co2monitor main.cc -lfltk -lhidapi

#include <FL/Fl.H>
#include <FL/Fl_Box.H>
#include <FL/Fl_Double_Window.H>
#include <FL/Fl_Tile.H>
#include <hidapi/hidapi.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

#if _WIN32
#define WIN32_LEAN_AND_MEAN
#include <process.h>
#include <windows.h>

typedef unsigned long Fl_Thread;
extern "C" {
typedef void *(__cdecl Fl_Thread_Func)(void *);
}
static int fl_create_thread(Fl_Thread &t, Fl_Thread_Func *f, void *p) {
  return t = (Fl_Thread)_beginthread((void(__cdecl *)(void *))f, 0, p);
}
#elif HAVE_PTHREAD_H
typedef pthread_t Fl_Thread;
extern "C" {
typedef void *(Fl_Thread_Func)(void *);
}
static int fl_create_thread(Fl_Thread &t, Fl_Thread_Func *f, void *p) {
  return pthread_create((pthread_t *)&t, 0, f, p);
}
#else
#error "Install pthreads"
#endif

typedef struct {
  double TemperatureKelvin;
  uint16_t CO2PPM;
} Reading;

static double ReadingTemperatureCelcius(Reading &r) {
  return r.TemperatureKelvin - 273.15;
}

typedef struct {
  hid_device *dev;
  unsigned char key[9];
  unsigned char buf[8];
} CO2Monitor;

static void CO2MonitorInit(CO2Monitor *cm) {
  cm->dev = hid_open(0x04d9, 0xa052, NULL);
  hid_send_feature_report(cm->dev, cm->key, 9);
}

static void CO2MonitorClose(CO2Monitor *cm) { hid_close(cm->dev); }

static void CO2MonitorRead(CO2Monitor *cm, Reading *r) {
  bool readTemp = false;
  bool readCO2 = false;
  while (hid_read(cm->dev, cm->buf, sizeof(char) * 8) > 0) {
    uint8_t first = cm->buf[2] ^ cm->key[0];
    uint8_t last = cm->buf[3] ^ cm->key[7];
    uint8_t unit = ((first >> 3) | (last << 5)) - 0x84;
    if (unit == 0x50) {
      uint8_t second = cm->buf[4] ^ cm->key[1];
      uint8_t third = cm->buf[0] ^ cm->key[2];
      uint8_t high = ((second >> 3) | (first << 5)) - 0x47;
      uint8_t low = ((third >> 3) | (second << 5)) - 0x56;
      uint16_t value = (((uint16_t)high) << 8) | ((uint16_t)low);
      r->CO2PPM = value;
      if (readTemp)
        break;
      readCO2 = true;
    } else if (unit == 0x42) {
      uint8_t second = cm->buf[4] ^ cm->key[1];
      uint8_t third = cm->buf[0] ^ cm->key[2];
      uint8_t high = ((second >> 3) | (first << 5)) - 0x47;
      uint8_t low = ((third >> 3) | (second << 5)) - 0x56;
      uint16_t value = (((uint16_t)high) << 8) | ((uint16_t)low);
      r->TemperatureKelvin = ((double)(value)) / 16.0;
      if (readCO2)
        break;
      readTemp = true;
    }
  }
}

static Fl_Thread thread;
static Fl_Window *win;
static Fl_Box *tempBox;
static Fl_Box *co2Box;

extern "C" {
static void *readFunc(void *p) {
  CO2Monitor cm = {0};
  Reading r;
  hid_init();
  CO2MonitorInit(&cm);
  for (;;) {
    CO2MonitorRead(&cm, &r);
    char fullString[21]; // -20.16 C | 12345 PPM
    sprintf(fullString, "%0.2f C | %d PPM", ReadingTemperatureCelcius(r),
            r.CO2PPM);
    win->label(fullString);
    char *tempString = fullString;
    char *co2String = strchr(fullString, '|');
    tempString[(co2String - fullString) - 1] = 0;
    co2String++;
    Fl::lock();
    co2Box->label(co2String);
    if (r.CO2PPM < 400)
      co2Box->labelcolor(fl_rgb_color(0x29, 0xAB, 0x87));
    else if (r.CO2PPM < 600)
      co2Box->labelcolor(fl_rgb_color(0x22, 0x8B, 0x22));
    else if (r.CO2PPM < 800)
      co2Box->labelcolor(fl_rgb_color(0x56, 0x82, 0x03));
    else if (r.CO2PPM < 1000)
      co2Box->labelcolor(fl_rgb_color(0xFD, 0xFF, 0x00));
    else if (r.CO2PPM < 1200)
      co2Box->labelcolor(fl_rgb_color(0xFD, 0x32, 0x0C));
    else
      co2Box->labelcolor(fl_rgb_color(0xFF, 0x00, 0x00));
    tempBox->label(tempString);
    Fl::unlock();
    Fl::awake();
  }
}
}

int main(int argc, char **argv) {
  const int W = 560;
  const int H = 350;
  win = new Fl_Double_Window(W, H, "0.0 C | XXX PPM");
  {
    tempBox = new Fl_Box(10, 30, W - 20, 160, "0.0 C");
    tempBox->labelsize(120);
    co2Box = new Fl_Box(10, 170, W - 20, 160, "XXX PPM");
    co2Box->labelsize(120);
  }
  win->color(fl_rgb_color(0xcc, 0xcc, 0xcc));
  win->position((Fl::w() - win->w()) / 2, (Fl::h() - win->h()) / 2);
  Fl::lock();
  fl_create_thread(thread, readFunc, NULL);
  win->show(argc, argv);
  return Fl::run();
}