Fez Panda K8000 induction problem

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1

Hello,

I have build a domotica system with a FEZ Panda and some velleman K8000 board cards.
The software i use is written by Bart Vanderhaegen.
This system runs perfect on 2 locations.
But on the 3 location it gives me large problems.
By an ukknow reason it swiths output on without a push on a button.
The communication between de FEZ Panda and the 3 K800 cards runs via I²C bus.
The lenght of this wires is max 50 cm.
To make a input on the K800 card you have to but 12V dc on a optocoupler and then the soft decide wich output to swith on.
I have connected al the GND together. The power supply is 12V DC and with a scopp i dont see any problems.
The only diffrent between the 3 installation is the housing of the whole system.
2 housings are made in Steel and the third is made from Plastic.
Can Anyone give me some tips to solve that problem.
I know its not easy but maybe 1 tip can help me further.

Many thanks Filip

2

Do you have another metal case to try? Seems pretty clear that this is a significant difference, and it “seems” like your problem is caused by electrical noise interfering with the device, so by doing this you will test that theory.

3

Filip, as Brett said, it sounds like environmental noise.

As a test, you could wrap the device in aluminum foil and ground it.