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?