Connecting the ADC pin to ground doesn't return '0'
Posted: Sun Nov 29, 2015 4:20 pmHi! I'm fairy new with ESP8266's, but got a lot of experience with AVRs and Arduinos. I've installed the ESP8266 addon for the Arduino IDE, and played around with basic sensors, Thingspeak logging and Blynk. I've used the DS18B20 as a temperature logger, and it works just fine. I also got an LM35dz i wanted to try, which is an analog temperature sensor.
To convert the analog signal to a readable temperature, I needed to experiment with the minimum and maximum values. I got a NodeMCU v1.0, with a 3.3v tolerant analog input (uses an onboard voltage divider). The weird thing is that If I connect the analog input directly to ground, the value (printed on the serial monitor, doesn't matter) the value flicks between 7 and 8. I've also tried to hook a wire straight on the ADC output on the onboard ESP-12E module. Still flicks between 7 and 8.
Is is possible to do some kind of calibration to fix this? Of course I can subtract the value, but what fun is that?
To convert the analog signal to a readable temperature, I needed to experiment with the minimum and maximum values. I got a NodeMCU v1.0, with a 3.3v tolerant analog input (uses an onboard voltage divider). The weird thing is that If I connect the analog input directly to ground, the value (printed on the serial monitor, doesn't matter) the value flicks between 7 and 8. I've also tried to hook a wire straight on the ADC output on the onboard ESP-12E module. Still flicks between 7 and 8.
Is is possible to do some kind of calibration to fix this? Of course I can subtract the value, but what fun is that?
