Thanks for all this info – it was most helpful! I realised after study of this info and your schematic that I had got my ADCs back-to-front. As I’m only using five ADC inputs (2V5 Vref, VT1, CT1–3), I connected (on my PCB) all those to what I thought was the ‘first’ ADC (based on your schematic 'ADC1–17 notation), but turns out to be the ‘second’ ADC. This allows me to omit the other ADC IC and its clamp diodes, and save a few cents! (Though my PCB allows for the fitting of the other ADC and diodes and connectors, for anyone wanting more.)
So when I finally worked out where my VT1 was connected, I went to the ‘Calibrate’ screen and was most pleased to see that the default factor (20) gave me an exact mains voltage reading, according to my Tektronix (true-RMS) DMM. Then I went about configuring my CTs, having also worked out where they were.
Needless to say, because the firmware is accessing the ‘second’ ADC all the time, the NodeMCU’s blue LED is lit continuously!
But some time later, I looked at the Status screen, and noticed that the mains voltage was low:
(it’s usually over 240V).
So I went back to the Inputs config screen to recheck the Calibrate (VT) screen, and found it now reporting ridiculously low voltages, changing rapidly and ranging from over 30 to –1!
So I’m a little lost, being unable to reconcile the Status and Calibrate screens and their very different (but both wrong) values.
Are you able to offer any suggestions on where I should start looking?