101 lines
2.4 KiB
C++
101 lines
2.4 KiB
C++
#include <Arduino.h>
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#include "MHZ19.h"
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#include "SSD1306Wire.h"
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#include <Adafruit_NeoPixel.h>
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// Maximum CO² levels for green and yellow, everything above is considered red.
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#define GREEN_CO2 800
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#define YELLOW_CO2 1500
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// Measurement interval in miliseconds
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#define INTERVAL 10000
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// Pins for MH-Z19
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#define RX_PIN 16
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#define TX_PIN 17
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// Pins for SD1306
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#define SDA_PIN 21
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#define SCL_PIN 22
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// Pin for LED
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#define LED_PIN 4
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MHZ19 myMHZ19;
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HardwareSerial mySerial(1);
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SSD1306Wire display(0x3c, SDA_PIN, SCL_PIN);
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Adafruit_NeoPixel pixels = Adafruit_NeoPixel(1, LED_PIN, NEO_RGB + NEO_KHZ400);
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unsigned long getDataTimer = 0;
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int lastvals[120];
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int dheight;
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void setup() {
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Serial.begin(9600);
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mySerial.begin(9600, SERIAL_8N1, RX_PIN, TX_PIN);
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myMHZ19.begin(mySerial);
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display.init();
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display.setContrast(255);
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delay(1000);
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display.clear();
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dheight = display.getHeight();
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myMHZ19.autoCalibration();
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// Fill array of last measurements with -1
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for (int x = 0; x <= 119; x = x + 1) {
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lastvals[x] = -1;
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}
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pixels.begin();
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pixels.setPixelColor(0, 30,0,0);
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pixels.show();
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}
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int calc_vpos_for_co2(int co2val, int display_height) {
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return display_height - int((float(display_height) / 3000) * co2val);
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}
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void set_led_color(int co2) {
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if (co2 < GREEN_CO2) {
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// Green
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pixels.setPixelColor(0, 30,0,0);
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} else if (co2 < YELLOW_CO2) {
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// Yellow
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pixels.setPixelColor(0, 40,40, 0);
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} else {
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// Red
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pixels.setPixelColor(0, 0,90,0);
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}
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pixels.show();
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}
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void loop() {
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if (millis() - getDataTimer >= INTERVAL) {
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// Get new CO² value.
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int CO2 = myMHZ19.getCO2();
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// Shift entries in array back one position.
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for (int x = 1; x <= 119; x = x + 1) {
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lastvals[x - 1] = lastvals[x];
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}
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// Add new measurement at the end.
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lastvals[119] = CO2;
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// Clear display and redraw whole graph.
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display.clear();
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for (int h = 1; h < 120; h = h + 1) {
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int curval = lastvals[h];
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if (curval > 0) {
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int vpos = calc_vpos_for_co2(lastvals[h], dheight);
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int vpos_last = calc_vpos_for_co2(lastvals[h - 1], dheight);
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display.drawLine(h - 1, vpos_last, h, vpos);
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}
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}
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// Set LED color and print value on display
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set_led_color(CO2);
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display.setLogBuffer(1, 30);
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display.println(CO2);
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display.drawLogBuffer(0, 0);
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display.display();
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// Debug output
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Serial.print("CO2 (ppm): ");
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Serial.println(CO2);
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getDataTimer = millis();
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}
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} |