ESP8266 Community Forum

- Sun Feb 12, 2017 8:32 am #62441 I have a nodemcu which I program via Arduino IDE. I have connected a VOC sensor to pin D1,D2 which is the SLC/SDA pins for nodemcu. They have pull-up resistor at 4,3kohm to 3.3V.

First I use i2c scanner code provided by arduino and get a response that I have the sensor connected at address 0x7, which is the correct address comparing to the datasheet for the sensor.

After I try to read values from the sensor at 0x9 (provided in the datasheet also). However I only get 0´s as output!! Probably something weird in the coding, perhaps someone could assist me in what I do wrong here?

In the code I request 100 bytes just to make sure to get everything, but I receive only 32 back. The datasheet says it should be 6 bytes on address 0x9. And I have tried hex and dec form but that doesnt work. Binary is the proper way I assume.

My Output:

Code: Select allStart
Bytes Available: 32
Data read: 00000000000000000000000000000000

Code:

Code: Select all#include <Wire.h>

int miscadr = 0b1110000;
//int miscadr = 0x7;
//int miscadr = 7;

void setup() {
   Serial.begin(115200);
  Wire.begin();
  delay(100);
}

void loop() {

  Serial.println();
   Serial.print("Start");
    Serial.println();

 Wire.beginTransmission(miscadr); //Start bit
 Wire.write(0b00001001); //Asking for registry 9
 //Wire.write(0x9); //Asking for registry 9
 //Wire.write(9); //Asking for registry 9

 Wire.endTransmission();
 Wire.requestFrom(miscadr, 100);
 Serial.print("Bytes Available: ");
 while(Wire.available()==0);
  Serial.print(Wire.available());
  Serial.println();
    Serial.print("Data read: ");
  while(Wire.available()!=0){
Serial.print(Wire.read());
  }
 Serial.println();
 delay(2000);
}