I have been working with the ACS712 current sensor for awhile now, and am getting awfully bizarre analog readings. On all pins that have zero voltage applied to them, I am getting a reading of 1780-1900. That is, the Photon is simply plugged into a breadboard and nothing else is wired to any of its pins.
Sample readings once a second:
Based on those numbers, it’s reporting about 1.4-1.5VDC going into it. That can’t magically be happening…can it?
When you say all the pins have zero voltage on them, do you mean that you have connected the analog pins to GND? That would be unusual and could indicate a power supply problem or hardware issue.
If you have not connected the pins to GND or some other definite source and they are just floating inputs, then they will just read random values.
I tried another Photon and a Spark Core and everything is okay. Yes the pins are simply grounded, no V+. I guess I’ll get rid of the odd one…
You may have had bad contact, since these readings do suggest a floating pin.
Before you bin that device try to rewire and also another A pin.