MH-Z14 ESP8266 Arduino example
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#include <ESP8266WiFi.h> | |
#include <WiFiClient.h> | |
#include <ESP8266WebServer.h> | |
#include <ESP8266mDNS.h> | |
#include <time.h> | |
const char* ssid = "co2_sensor"; | |
const char* password = "1qazxsw2"; | |
ESP8266WebServer server(80); | |
const int led = BUILTIN_LED; | |
int getCO2(); | |
int pwm_co2 = 0; | |
void pwm_in_interrupt() { | |
static int t_last = 0; | |
int t = micros(); | |
if (digitalRead(D5) == 0) { | |
pwm_co2 = (t - t_last - 2) * 4 / 1000; | |
} | |
t_last = t; | |
} | |
void setup(void) { | |
WiFi.mode(WIFI_AP); | |
pinMode(led, OUTPUT); | |
digitalWrite(led, 0); | |
Serial.begin(9600); | |
Serial.swap(); | |
WiFi.softAP(ssid, password); | |
attachInterrupt(D5, pwm_in_interrupt, CHANGE); | |
// // Wait for connection | |
// while (WiFi.status() != WL_CONNECTED) { | |
// digitalWrite(led, 1); | |
// delay(400); | |
// digitalWrite(led, 0); | |
// delay(100); | |
// } | |
// if (MDNS.begin("esp8266-mh-z14")) { | |
// MDNS.addService("http", "tcp", 80); | |
// } | |
// configTime(3600 * 3, 0, "pool.ntp.org"); | |
server.on("/", []() { | |
digitalWrite(led, 0); | |
int co2 = getCO2(); | |
// time_t ts; | |
// time(&ts); | |
int ts = millis(); | |
String response = String("{\"co2\":") + co2 + ", \"pwm_co2\":" + pwm_co2 + ", \"time\":" + ts + "}\n"; | |
server.send(200, "text/json", response); | |
digitalWrite(led, 1); | |
}); | |
server.begin(); | |
delay(5000); | |
digitalWrite(led, 1); | |
} | |
void loop(void) { | |
server.handleClient(); | |
} | |
const uint8_t cmd[9] = {0xFF,0x01,0x86,0x00,0x00,0x00,0x00,0x00,0x79}; | |
int getCO2() { | |
uint8_t response[9]; | |
Serial.write(cmd, 9); | |
if (Serial.readBytes(response, 9) == 9) { | |
int responseHigh = (int) response[2]; | |
int responseLow = (int) response[3]; | |
int ppm = (256 * responseHigh) + responseLow; | |
return ppm; | |
} | |
return -1; | |
} |
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I'm having problems reading the UART register. It looked like the values were correct once but then switched to this:
Address 0 FF
Address 1 86
Address 2 7
Address 3 D0
Address 4 43
Address 5 0
Address 6 0
Address 7 0
Address 8 60
I sent the device this request
byte addArray[] = {0xFF, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x79};