Using 74LS32 "OR" gates

Other Hardware General Electronics
1

This a question about "OR" gates. The Arduino's work correctly.

I have 11 Arduino's linked together by a cable. I have not interfaced them directly but via "OR" gates. Each Arduino has one output and one input from its neighbour. The two way communication uses 3 wires, one common ground and the two others for the signal.

There is a common power supply, a legacy 24V, which is reduced to 12V and then 5V by 78xx devices at each location.

All work correctly except for 1 output.

Unconnected, the sending "OR" gate switches fine, 0.13V "off" and 4.25V "on" as controlled by the processor.

By using "jump leads" to connect to either ground or +5V, the input of the receiving "OR" gate also works fine and can be "read" by its processor.

However, connect the sending "OR" gate to the receiving "OR" gate by the cable, I then get a negative output from the sending "OR" gate, -1.5V, when "off".

The output going back the other way is okay. Its the same common ground!

The "on" voltage is then only +2V, which is not high enough to change the state of the receiving "OR" gate.

Can anyone explain and then help me solve this phenomenon?

Confused from the UK.

2

Can you post a circuit diagram and/or a picture of your project?

At a pure guess, something doesn't have the ground and/or supply rail that you think it has.

Yours,
TonyWilk

3

Agree we the previous poster that there is connection/ground issue but I'm having difficulty understanding the configuration. Even a basic block diagram showing two or three nodes, the logic gates and the interconnections should be enough to help comment on the possible source of the trouble.

4

Are all having this issue, or only one? You might want to also include the code for the offending arduinos on top of the circuit diagrams. Use code tags please