/*
* The MySensors Arduino library handles the wireless radio link and protocol
* between your home built sensors/actuators and HA controller of choice.
* The sensors forms a self healing radio network with optional repeaters. Each
* repeater and gateway builds a routing tables in EEPROM which keeps track of the
* network topology allowing messages to be routed to nodes.
*
* Created by Henrik Ekblad <henrik.ekblad@mysensors.org>
* Copyright (C) 2013-2019 Sensnology AB
* Full contributor list: https://github.com/mysensors/MySensors/graphs/contributors
*
* Documentation: http://www.mysensors.org
* Support Forum: http://forum.mysensors.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
*******************************
*
* DESCRIPTION
*
* MH-Z14 CO2 sensor
*
* Wiring:
* Pad 1, Pad 5: Vin (Voltage input 4.5V-6V)
* Pad 2, Pad 3, Pad 12: GND
* Pad 6: PWM output ==> pin 6
*
* From: http://davidegironi.blogspot.fr/2014/01/co2-meter-using-ndir-infrared-mh-z14.html
* MH-Z14 has a PWM output, with a sensitivity range of 0ppm to 2000ppm CO2, an accuracy of ±200ppm.
* The cycle is 1004ms±5%, given the duty cicle Th (pulse high), Tl is 1004-Th, we can convert it to CO2 value using the formula:
* CO2ppm = 2000 * (Th - 2ms) /(Th + Tl - 4ms)
* From: http://airqualityegg.wikispaces.com/Sensor+Tests
* - response time is less than 30 s
* - 3 minute warm up time
* datasheet: http://www.futurlec.com/Datasheet/Sensor/MH-Z14.pdf
* Contributor: epierre
*/
// Enable debug prints to serial monitor
#define MY_DEBUG
// Enable and select radio type attached
#define MY_RADIO_RF24
//#define MY_RADIO_NRF5_ESB
//#define MY_RADIO_RFM69
//#define MY_RADIO_RFM95
#include <MySensors.h>
#define CHILD_ID_AIQ 0
#define AIQ_SENSOR_ANALOG_PIN 6
uint32_t SLEEP_TIME = 30*1000; // Sleep time between reads (in milliseconds)
float valAIQ =0.0;
float lastAIQ =0.0;
MyMessage msg(CHILD_ID_AIQ, V_LEVEL);
MyMessage msg2(CHILD_ID_AIQ, V_UNIT_PREFIX);
void setup()
{
pinMode(AIQ_SENSOR_ANALOG_PIN, INPUT);
}
void presentation()
{
// Send the sketch version information to the gateway and Controller
sendSketchInfo("AIQ Sensor CO2 MH-Z14", "1.0");
// Register all sensors to gateway (they will be created as child devices)
present(CHILD_ID_AIQ, S_AIR_QUALITY);
send(msg2.set("ppm"));
}
void loop()
{
//uint32_t duration = pulseIn(AIQ_SENSOR_ANALOG_PIN, HIGH);
while(digitalRead(AIQ_SENSOR_ANALOG_PIN) == HIGH) {
;
}
//wait for the pin to go HIGH and measure HIGH time
uint32_t duration = pulseIn(AIQ_SENSOR_ANALOG_PIN, HIGH);
//Serial.print(duration/1000); Serial.println(" ms ");
//from datasheet
//CO2 ppm = 2000 * (Th - 2ms) / (Th + Tl - 4ms)
// given Tl + Th = 1004
// Tl = 1004 - Th
// = 2000 * (Th - 2ms) / (Th + 1004 - Th -4ms)
// = 2000 * (Th - 2ms) / 1000 = 2 * (Th - 2ms)
long co2ppm = 2 * ((duration/1000) - 2);
//Serial.print(co2ppm);
if ((co2ppm != lastAIQ)&&(abs(co2ppm-lastAIQ)>=10)) {
send(msg.set((int32_t)ceil(co2ppm)));
lastAIQ = ceil(co2ppm);
}
//Serial.println();
// Power down the radio. Note that the radio will get powered back up
// on the next write() call.
sleep(SLEEP_TIME); //sleep for: sleepTime
}