Automation HAT, spurious signals on empty ADC channels

@peteky wrote:

Spurious signals on empty ADC channels

Hello friends at Pimoroni and users everywhere.

I just installed an Automation hat to read 24V
digital signals from out Fanuc robot.
It works like a charm, excellent.

HW: Automation HAT, Raspi 3, latest raspbian updated & upgraded.
Used the easy curl-installation script.

My setup:

• three digital 24vdc robot output lines connected to
  automation hat input lines
• HAT GND plane connected to robot signal ground
• everything works perfectly

Mystery part:

• I connected the raspi 5V from screw terminal to
  ADC line 1 and got the voltage ok.
• however I get spurious readings from empty lines
  (with led flashes) ADC 2 & 3

Summary:

• this is not an issue, I’m super happy with digital
  input, very nice!
• I must be missing something fundamental here?

So comments would be extra nice, please?

all the best
Pete (Pekka) Kyrenius
Aalto University FINLAND

Posts: 4

Participants: 2

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