/*

Version: 1.0.3

Components:

- Arduino Nano

- CO2 - MH-Z19B

- Temperature, humidity, pressure - BME280

- OLED - SSD1306 128x32

- Code, fonts, layout etc - https://github.com/killadog/CO2meter

Mode 0 Mode 1

┌───────────────────────┬───────────────────────┐

Sensor 0 │ Current temperature | Min-Max temperature │

├───────────────────────┼───────────────────────┤

Sensor 1 │ Current humidity | Min-Max humidity │

├───────────────────────┼───────────────────────┤

Sensor 2 │ Current pressure | Min-Max pressure │

├───────────────────────┼───────────────────────┤

Sensor 3 │ Current CO2 | Min-Max CO2 │

├───────────────────────┼───────────────────────┤

Sensor 4 │ ALL sensors | Ver. & Year │

└───────────────────────┴───────────────────────┘

*/

#include <SparkFunBME280.h> // https://github.com/sparkfun/SparkFun_BME280_Arduino_Library

#include <U8g2lib.h> // https://github.com/olikraus/u8g2

#include <GyverButton.h> // https://github.com/AlexGyver/GyverLibs/tree/master/GyverButton

#include <MHZ19.h> // https://github.com/WifWaf/MH-Z19

#include <SoftwareSerial.h>

#define RX_PIN 4 // RX pin

#define TX_PIN 5 // TX pin

#define RED_PIN 6 // RED pin

#define YELLOW_PIN 7 // YELLOW pin

#define GREEN_PIN 8 // GREEN pin

#define BUTTON_PIN 9 // BUTTON pin

#define SDA_PIN A4 // SDA pin

#define SCL_PIN A5 // SCL pin

const uint8_t SENSORS = 4; // number of sensors

float VALUE[SENSORS]; // current value of each sensor

float CALIBRATION[SENSORS] = { -0.3, 0, 0, 0}; // calibration of each sensor (t,%,T,ppm)

uint16_t MIN[SENSORS]; // Min value of each sensor

uint16_t MAX[SENSORS]; // Max value of each sensor

boolean MODE = 0; // start mode (0 - normal, 1 - min/max)

uint8_t SENSOR_NUMBER = 4; // start sensor (screen)

uint32_t SENSORS_TIMESTAMP = millis();

#define CHECK_TIME 10000 // sensors check time in millis

boolean DISPLAY_MODE = 0; // normal (0) or rotate (1) screen

BME280 bme280;

U8G2_SSD1306_128X32_UNIVISION_1_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE, /* clock=*/ SCL, /* data=*/ SDA);

MHZ19 myMHZ19;

GButton button_select(BUTTON_PIN, LOW_PULL, NORM_OPEN);

SoftwareSerial co2(RX_PIN, TX_PIN);

const uint8_t lcdnums_10x16[330] U8G2_FONT_SECTION("lcdnums_10x16") =

"\26\0\4\3\5\4\3\4\6\26\17\0\373\12\0\0\0\0\0\0\0\1\61$ \365:\66\224\224\310\220"

"H\210HL\224H\210H\34\210H\210HHD\234\224\310P\251\241R#%\33\212;l\214\305D\305"

"\244\210\11\211\31\11\314d&$&*&*&l\2\0&\13\346\274)\34\224\10\351\4\0'\5\0"

"\210)(\5\0\210))\5\0\210)*\14\345\274gL\304\350&b\2\0+\5\0\210),\5\0"

"\210)-\5\0\210).\6b\70$\30/\5\0\210)\60\20\351\71k\134DTL\361\277\232\250\210"

"\270\0\61\13\346=+\320\14\351rP\62\24\351\71+\34\204X\304\351\302B\302BNw\21&\7"

"\1\63\24\351\71+\34\204X\304\351\244\42\342\62N\27\26\7\22\0\64\16\351\71+H\361\325DE\304"

"e\234>\65\24\351\71k\34HX\310i\27ar\20\247\27\26\7\22\0\66\25\351\71k\34HX\310"

"ix\21Q\61\305\253\211\212\210\13\0\67\16\351\71+\34\204X\304)\323\235~\4\70\27\351\71k\134"

"DTLq\65Q\21q\21\67\305\325DE\304\5\0\71\25\351\71k\134DTLq\65Q\21q\31"

"\247\13\213\3\11\0\0\0\0";

const uint8_t lcdnums_12x32[407] U8G2_FONT_SECTION("lcdnums_12x32") =

"\26\0\4\3\4\6\4\6\6\21 \0\354\14\0\0\0\0\0\0\0\1~$%\237(\23\303\310H\214"

"HDH\204\304HDH\204\304HDHD\12\222\221\210\10\241\64Bi\204\322\10\245\11%%Y-"

"\303\306TLPLPLPLPLPL\324L\134\276\231\212\11\212\11\212\11\212\11\212\11\212\211\232"

"\0&\13\226\354\230\302A\211\220>\1'\6\0 \10\2(\6\0 \10\2)\6\0 \10\2*\14"

"\226\354\230\6E\220>\212\240\0+\6\0 \10\2,\6\0 \10\2-\10\66\350\246\302\3\2.\10"

"R\60\243\302\301\0/\6\0 \10\2\60\25\12*\343\306AD\204\305\30\377\377\377g\23\26\21\7\21"

"\0\61\16\6\62\343\2\315\220\376\377\377O\16\12\62\30\12*\343\302\201\310E\240\376/,&,&,"

"\4\365\30qr \63\34\12*\343\302\3\212\210\3A\375\207\7\23\7\23\7\21\201\372\277\70\70\230"

"\70\230\0\64\23\12*\343\202\30\377\277\240\230\260\210\70\210\24\324\377\7\65\30\12*\343\306\301\304\205\240"

"\376/,\42,\42,\4\365\377\342\301\4\0\66\32\12*\343\306\301\304\205\240\376\207\21'\27\22\25d"

"\374?\233\260\210\70\210\0\67\26\12*\343\302\201\310E\240\356\4\345\4\345\4\345\4\365\377?\2\70\35"

"\12*\343\306AD\204\305\30\377g\23\26\21\7\21\21\26c\374?\233\260\210\70\210\0\71\30\12*\343"

"\306AD\204\305\30\377/*$N.\2\365\377\342\301\4\0\0\0\0";

void setup()

{

Serial.begin(9600);

pinMode(SDA_PIN, INPUT_PULLUP);

pinMode(SCL_PIN, INPUT_PULLUP);

pinMode(GREEN_PIN, OUTPUT);

pinMode(YELLOW_PIN, OUTPUT);

pinMode(RED_PIN, OUTPUT);

button_select.setDebounce(50); // настройка антидребезга (default 80 ms)

button_select.setTimeout(1500); // настройка таймаута на удержание (default 500 ms)

button_select.setClickTimeout(200); // настройка таймаута между кликами (default 300 ms)

digitalWrite(GREEN_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(RED_PIN, LOW);

u8g2.begin();

u8g2.setDrawColor(1);

bme280.settings.I2CAddress = 0x76;

bme280.settings.commInterface = I2C_MODE;

bme280.begin();

if (!bme280.beginI2C()) //Begin communication over I2C

{

Serial.println(F("BME280 did not respond. Please check wiring."));

while (1); //Freeze

}

co2.begin(9600); // Begin Stream with MHZ19 baudrate

myMHZ19.begin(co2); // *Important, Pass your Stream reference

myMHZ19.setRange(2000); // 2000ppm is the most accurate and advised

myMHZ19.autoCalibration(0); // Turn auto calibration OFF (disable with autoCalibration(false))

for (uint8_t s = 0; s < SENSORS; s++)

{

MIN[s] = 3000; //INCORRECT(!) values for minimums

}

START_SCREEN();

}

void loop()

{

u8g2.firstPage();

do {

draw();

} while (u8g2.nextPage());

CHECK_BUTTON();

if (CHECK_TIME < millis() - SENSORS_TIMESTAMP)

{

CHECK_SENSORS();

}

}

void draw()

{

u8g2.setFont(lcdnums_12x32);

switch (SENSOR_NUMBER)

{

case 0: SENSOR_0(); break;

case 1: SENSOR_1(); break;

case 2: SENSOR_2(); break;

case 3: SENSOR_3(); break;

case 4: SENSOR_4(); break;

}

}

void SENSOR_0() //Temperature

{

switch (MODE)

{

case 0:

u8g2.setCursor(32, 12);

u8g2.print(VALUE[0], 1);

u8g2.print(F("*")); //degree symbol

break;

case 1:

u8g2.setCursor(0, 12);

u8g2.print(MIN[0]);

u8g2.print(F("-"));

u8g2.print(MAX[0]);

u8g2.print(F("*")); //degree symbol

break;

}

}

void SENSOR_1() //Humidity

{

switch (MODE)

{

case 0:

u8g2.setCursor(32, 12);

u8g2.print(VALUE[1], 1);

u8g2.print(F("%"));

break;

case 1:

u8g2.setCursor(0, 12);

u8g2.print(MIN[1]);

u8g2.print(F("-"));

u8g2.print(MAX[1]);

u8g2.print(F("%"));

break;

}

}

void SENSOR_2() //Pressure

{

switch (MODE)

{

case 0:

u8g2.setCursor(26, 12);

u8g2.print(VALUE[2], 1);

u8g2.print(F("&")); //Torr symbol

break;

case 1:

u8g2.setCursor(0, 12);

u8g2.print(MIN[2]);

u8g2.print(F("-"));

u8g2.print(MAX[2]);

u8g2.print(F("&")); //Torr symbol

break;

}

}

void SENSOR_3() //CO2

{

switch (MODE)

{

case 0:

u8g2.setCursor(32, 12);

u8g2.print(VALUE[3], 0);

u8g2.print(F("$")); //ppm symbol

break;

case 1:

u8g2.setCursor(0, 12);

u8g2.print(MIN[3]);

u8g2.print(F("-"));

u8g2.print(MAX[3]);

u8g2.print(F("$")); //ppm symbol

break;

}

}

void SENSOR_4()

{

switch (MODE)

{

case 0: //show all sensors

u8g2.setFont(lcdnums_10x16);

u8g2.setCursor(0, 10);

u8g2.print(VALUE[0], 1);

u8g2.print(F("*")); //degree symbol

u8g2.setCursor(0, 27);

u8g2.print(VALUE[1], 1);

u8g2.print(F("%"));

u8g2.setCursor(60, 10);

u8g2.print(VALUE[2], 1);

u8g2.print(F("&")); //Torr symbol

u8g2.setCursor(60, 27);

u8g2.print(VALUE[3], 0);

u8g2.print(F("$")); //ppm symbol

break;

case 1:

u8g2.setFont(lcdnums_10x16);

u8g2.setCursor(50, 10);

u8g2.print(" 1.0.3"); //version

u8g2.setCursor(10, 27);

u8g2.print("2019---2020"); //years

break;

}

}

void CHECK_BUTTON()

{

button_select.tick();

if (button_select.isSingle())

{

SENSOR_NUMBER++;

if (SENSOR_NUMBER > SENSORS) SENSOR_NUMBER = 0;

Serial.print(F("Single click. Sensor "));

Serial.print(SENSOR_NUMBER);

Serial.print(F(" Mode "));

Serial.println(MODE);

}

if (button_select.isDouble())

{

MODE = !MODE;

Serial.print(F("Double click. Sensor "));

Serial.print(SENSOR_NUMBER);

Serial.print(F(" Mode "));

Serial.println(MODE);

}

if (button_select.isHolded())

{

DISPLAY_MODE = !DISPLAY_MODE;

if (DISPLAY_MODE) u8g2.setDisplayRotation(U8G2_R0);

else u8g2.setDisplayRotation(U8G2_R2);

Serial.println(F("Holded. Rotate display."));

}

}

void CHECK_SENSORS()

{

for (uint8_t s = 0; s < SENSORS; s++)

{

switch (s)

{

case 0:

VALUE[s] = bme280.readTempC() + CALIBRATION[s];

if (VALUE[s] < MIN[s]) MIN[s] = VALUE[s];

if (VALUE[s] > MAX[s]) MAX[s] = VALUE[s];

Serial.print (F("T: "));

Serial.print(VALUE[s], 1);

Serial.print (F("°C ("));

Serial.print(MIN[s], 1);

Serial.print(F("/"));

Serial.print(MAX[s], 1);

Serial.print(F(") "));

break;

case 1:

VALUE[s] = bme280.readFloatHumidity() + CALIBRATION[s];

if (VALUE[s] < MIN[s]) MIN[s] = VALUE[s];

if (VALUE[s] > MAX[s]) MAX[s] = VALUE[s];

Serial.print (F("H: "));

Serial.print(VALUE[s], 1);

// Serial.print (F("% (")); //it breaks chrome extension

Serial.print (F(" (")); //that's why

Serial.print(MIN[s], 1);

Serial.print(F("/"));

Serial.print(MAX[s], 1);

Serial.print(F(") "));

break;

case 2:

VALUE[s] = bme280.readFloatPressure() / 133.3224 + CALIBRATION[s];

if (VALUE[s] < MIN[s]) MIN[s] = VALUE[s];

if (VALUE[s] > MAX[s]) MAX[s] = VALUE[s];

Serial.print (F("P: "));

Serial.print(VALUE[s], 1);

Serial.print (F("T ("));

Serial.print(MIN[s], 1);

Serial.print(F("/"));

Serial.print(MAX[s], 1);

Serial.print(F(") "));

break;

case 3:

VALUE[s] = myMHZ19.getCO2() + CALIBRATION[s];

if (VALUE[s] == 0) RESTART(); //Error in MHZ19. Restart if ppm is 0

if (VALUE[s] < MIN[s]) MIN[s] = VALUE[s];

if (VALUE[s] > MAX[s]) MAX[s] = VALUE[s];

Serial.print (F("CO2:"));

Serial.print(VALUE[s], 0);

Serial.print (F(" ppm ("));

Serial.print(MIN[s], 1);

Serial.print(F("/"));

Serial.print(MAX[s], 1);

Serial.println(F(")"));

break;

}

}

CHECK_DANGER();

SENSORS_TIMESTAMP = millis();

}

void CHECK_DANGER()

{

uint16_t VALUE = myMHZ19.getCO2() + CALIBRATION[3] ;

if (VALUE < 800)

{

digitalWrite(GREEN_PIN, HIGH);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(RED_PIN, LOW);

}

if ((VALUE >= 800) && (VALUE < 1000))

{

digitalWrite(GREEN_PIN, LOW);

digitalWrite(YELLOW_PIN, HIGH);

digitalWrite(RED_PIN, LOW);

}

if (VALUE >= 1000)

{

digitalWrite(GREEN_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(RED_PIN, HIGH);

}

}

void START_SCREEN() //Countdown. Center text

{

u8g2.setFont(lcdnums_12x32);

uint32_t START_TIME = millis();

while (millis() < START_TIME + CHECK_TIME)

{

u8g2.firstPage();

do {

char charBuf[3];

String COUNTDOWN = String((CHECK_TIME + 1000 - millis()) / 1000);

COUNTDOWN.toCharArray(charBuf, 3);

u8g2_uint_t TEXT_WIDTH = u8g2.getStrWidth(charBuf);

u8g2.drawStr((128 - TEXT_WIDTH) / 2, 12, charBuf);

} while (u8g2.nextPage());

}

}

void RESTART() //FULL RESTART

{

Serial.println(F("RESTART"));

asm("JMP 0");

}