Error code 3 and 4

[lata22]

Hi, I´m trying to get this sensor working but unfourtunately im not able.

I´m using MH-Z19B 0-5000ppm sensor and ESP8266 Nodemcu v3 I´ve connected the MH-Z19B tx pin to ESP8266 D1 pin and MH-Z19B rx pin to ESP8266 D2 pin and MH-Z19B Vin to the positive of a 5v 2A source and the MH-Z19B Gnd to the ground of the same power source.

And I´m using this code:

include

include

SoftwareSerial ss(D4,D5); //Maybe the problem is in this constructor that I´m passing the wrong pin numbers? I´ve already tried withoud the 'D' MHZ19 mhz(&ss);

void setup() { Serial.begin(9600); Serial.println(F("Starting..."));

ss.begin(9600); }

void loop() { MHZ19_RESULT response = mhz.retrieveData(); if (response == MHZ19_RESULT_OK) { Serial.print(F("CO2: ")); Serial.println(mhz.getCO2()); Serial.print(F("Min CO2: ")); Serial.println(mhz.getMinCO2()); Serial.print(F("Temperature: ")); Serial.println(mhz.getTemperature()); Serial.print(F("Accuracy: ")); Serial.println(mhz.getAccuracy()); } else { Serial.print(F("Error, code: ")); Serial.println(response); }

delay(1000); }

And I´m getting: Error, code: 3 and sometimes Error, code: 4

What am I doing wrong?

Thanks!!

[lata22]

Well now with this code:

include

include

SoftwareSerial ss(5,4); MHZ19 mhz(&ss);

void setup() { Serial.begin(115200); Serial.println(F("Starting..."));

ss.begin(9600); }

void loop() { while (ss.available() > 0) { Serial.print("."); ss.read(); }

MHZ19_RESULT response = mhz.retrieveData(); if (response == MHZ19_RESULT_OK) { Serial.print(F("CO2: ")); Serial.println(mhz.getCO2()); Serial.print(F("Min CO2: ")); Serial.println(mhz.getMinCO2()); Serial.print(F("Temperature: ")); Serial.println(mhz.getTemperature()); Serial.print(F("Accuracy: ")); Serial.println(mhz.getAccuracy()); } else { Serial.print(F("Error, code: ")); Serial.println(response); }

delay(10000); }

I´m getting values but I don´t know how to convert it to ppm. I´m getting: 11:05:07.833 -> CO2: 2142 11:05:07.833 -> Min CO2: 0 11:05:07.833 -> Temperature: 27 11:05:07.833 -> Accuracy: 0

How do I convert the CO2 2142 value to ppm? This number can´t be in ppm because I would rather be dead with this amount of co2

[strange-v]

It is already in ppm.

[strange-v]

Sorry, didn't have time to answer your question in a more detailed manner. A few additional points:

• it takes 24 hours for the sensor to re-calibrate itself, so leave it connected and wait (and open a window for a few minutes)
• 2142 ppm isn't as high as you think

2,000-5,000 ppm | Headaches, sleepiness and stagnant, stale, stuffy air. Poor concentration, loss of attention, increased heart rate and slight nausea may also be present.

[strange-v]

Closed due to inactivity.