MySensors Library & Examples  2.3.2
CO2Sensor.ino
1 /*
2  * The MySensors Arduino library handles the wireless radio link and protocol
3  * between your home built sensors/actuators and HA controller of choice.
4  * The sensors forms a self healing radio network with optional repeaters. Each
5  * repeater and gateway builds a routing tables in EEPROM which keeps track of the
6  * network topology allowing messages to be routed to nodes.
7  *
8  * Created by Henrik Ekblad <[email protected]>
9  * Copyright (C) 2013-2019 Sensnology AB
10  * Full contributor list: https://github.com/mysensors/MySensors/graphs/contributors
11  *
12  * Documentation: http://www.mysensors.org
13  * Support Forum: http://forum.mysensors.org
14  *
15  * This program is free software; you can redistribute it and/or
16  * modify it under the terms of the GNU General Public License
17  * version 2 as published by the Free Software Foundation.
18  *
19  *******************************
20  *
21  * DESCRIPTION
22  *
23  * MH-Z14 CO2 sensor
24  *
25  * Wiring:
26  * Pad 1, Pad 5: Vin (Voltage input 4.5V-6V)
27  * Pad 2, Pad 3, Pad 12: GND
28  * Pad 6: PWM output ==> pin 6
29  *
30  * From: http://davidegironi.blogspot.fr/2014/01/co2-meter-using-ndir-infrared-mh-z14.html
31  * MH-Z14 has a PWM output, with a sensitivity range of 0ppm to 2000ppm CO2, an accuracy of ±200ppm.
32  * 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:
33  * CO2ppm = 2000 * (Th - 2ms) /(Th + Tl - 4ms)
34  * From: http://airqualityegg.wikispaces.com/Sensor+Tests
35  * - response time is less than 30 s
36  * - 3 minute warm up time
37  * datasheet: http://www.futurlec.com/Datasheet/Sensor/MH-Z14.pdf
38  * Contributor: epierre
39  */
40 
41 // Enable debug prints to serial monitor
42 #define MY_DEBUG
43 
44 // Enable and select radio type attached
45 #define MY_RADIO_RF24
46 //#define MY_RADIO_NRF5_ESB
47 //#define MY_RADIO_RFM69
48 //#define MY_RADIO_RFM95
49 
50 #include <MySensors.h>
51 
52 #define CHILD_ID_AIQ 0
53 #define AIQ_SENSOR_ANALOG_PIN 6
54 
55 uint32_t SLEEP_TIME = 30*1000; // Sleep time between reads (in milliseconds)
56 
57 float valAIQ =0.0;
58 float lastAIQ =0.0;
59 
60 MyMessage msg(CHILD_ID_AIQ, V_LEVEL);
61 MyMessage msg2(CHILD_ID_AIQ, V_UNIT_PREFIX);
62 
63 void setup()
64 {
65  pinMode(AIQ_SENSOR_ANALOG_PIN, INPUT);
66 }
67 
69 {
70  // Send the sketch version information to the gateway and Controller
71  sendSketchInfo("AIQ Sensor CO2 MH-Z14", "1.0");
72 
73  // Register all sensors to gateway (they will be created as child devices)
74  present(CHILD_ID_AIQ, S_AIR_QUALITY);
75  send(msg2.set("ppm"));
76 }
77 
78 void loop()
79 {
80 
81  //uint32_t duration = pulseIn(AIQ_SENSOR_ANALOG_PIN, HIGH);
82  while(digitalRead(AIQ_SENSOR_ANALOG_PIN) == HIGH) {
83  ;
84  }
85  //wait for the pin to go HIGH and measure HIGH time
86  uint32_t duration = pulseIn(AIQ_SENSOR_ANALOG_PIN, HIGH);
87 
88  //Serial.print(duration/1000); Serial.println(" ms ");
89  //from datasheet
90  //CO2 ppm = 2000 * (Th - 2ms) / (Th + Tl - 4ms)
91  // given Tl + Th = 1004
92  // Tl = 1004 - Th
93  // = 2000 * (Th - 2ms) / (Th + 1004 - Th -4ms)
94  // = 2000 * (Th - 2ms) / 1000 = 2 * (Th - 2ms)
95  long co2ppm = 2 * ((duration/1000) - 2);
96  //Serial.print(co2ppm);
97  if ((co2ppm != lastAIQ)&&(abs(co2ppm-lastAIQ)>=10)) {
98  send(msg.set((int32_t)ceil(co2ppm)));
99  lastAIQ = ceil(co2ppm);
100  }
101 
102  //Serial.println();
103 
104  // Power down the radio. Note that the radio will get powered back up
105  // on the next write() call.
106  sleep(SLEEP_TIME); //sleep for: sleepTime
107 }
MyMessage is used to create, manipulate, send and read MySensors messages.
Definition: MyMessage.h:289
bool sendSketchInfo(const char *name, const char *version, const bool requestEcho=false)
API declaration for MySensors.
bool send(MyMessage &msg, const bool requestEcho=false)
bool present(const uint8_t sensorId, const mysensors_sensor_t sensorType, const char *description="", const bool requestEcho=false)
void setup()
Called after node initialises but before main loop.
Definition: CO2Sensor.ino:63
int8_t sleep(const uint32_t sleepingMS, const bool smartSleep=false)
void presentation()
Node presentation.
Definition: CO2Sensor.ino:68
#define HIGH
Definition: bcm2835.h:572
MyMessage & set(const void *payload, const size_t length)
Set entire payload.
void loop()
Main loop.
Definition: CO2Sensor.ino:78