PPMUart && Temperature N/A

[quintendewilde]

Hi,

I get this in the serial monitor.

----- Time from start: 1099 s PPMuart: n/a, PPMpwm: 634, Temperature: n/a

Running this on a Wemos D1

With this sketch

include

include

include

// pin for pwm reading

define CO2_IN 16

// pin for uart reading

define MH_Z19_RX D1 // D7

define MH_Z19_TX D2 // D6

MHZ co2(MH_Z19_RX, MH_Z19_TX, CO2_IN, MHZ19B);

void setup() { Serial.begin(9600); pinMode(CO2_IN, INPUT); delay(100); Serial.println("MHZ 19B");

// enable debug to get addition information // co2.setDebug(true);

if (co2.isPreHeating()) { Serial.print("Preheating"); while (co2.isPreHeating()) { Serial.print("."); delay(5000); } Serial.println(); } }

void loop() { Serial.print("\n----- Time from start: "); Serial.print(millis() / 1000); Serial.println(" s");

int ppm_uart = co2.readCO2UART(); Serial.print("PPMuart: ");

if (ppm_uart > 0) { Serial.print(ppm_uart); } else { Serial.print("n/a"); }

int ppm_pwm = co2.readCO2PWM(); Serial.print(", PPMpwm: "); Serial.print(ppm_pwm);

int temperature = co2.getLastTemperature(); Serial.print(", Temperature: ");

if (temperature > 0) { Serial.println(temperature); } else { Serial.println("n/a"); }

Serial.println("\n------------------------------"); delay(5000); }

[tobiasschuerg]

PPMuart: n/a, PPMpwm: 634, Temperature: n/a Seems like reading via pwm worked and reading via uart did not.

This probably is a hardware issue so you should to check if your wiring is correct and if the pins you specified D1 and D2 are the right pins for serial on the WeMos.

[nbarjolin]

Hello, I would like to let you know that I ran into a similar issue with readCO2UART() failing because int count = _serial->readBytes(response, 9); was returning -1.

This was due to an outdated version of EspSoftwareSerial. Problem was solved by updating the Arduino core for ESP8266 to the latest version (2.7.4, was 2.6.3 initially).

Best regards,