Intercepting a signal

I want to hack a device, change the function of it. I’ve found a wire I want to cut, and insert an AVR-chip (maybe an attiny85) to change the signal. But I don’t know how to connect the chip.

The wire can either do nothing, have 1.5V in one direction, or have 1.5V in the other direction. I need to be able to read this, and I need to be able to generate another signal with the same 3 variations. If it’s any help, I don’t care about polarity when reading, but I need to be able to write both polarities.

I don’t really know where to start, I’m still very new to electronics. :slight_smile:

Please be somewhat more precise. Do you also need to parse the existing signal or do you only need to inject your own signal?

I do need to parse the input. The output should only be what I choose to write.

The wire can either do nothing

Even if it has no voltage on it it is not doing nothing it is providing a low impedance path to ground. The arduino can not handle negitave signals so you will first have to convert it to a positave signal process it and then turn it back. For this you wil need a negitave power supply and some transistors. You will also need more than one digital input / output pin for the signal because you have two three levels an you can only represent two levels on a digital pin. It is a bit complex for a beginner.

myplacedk: The wire can either do nothing, have 1.5V in one direction, or have 1.5V in the other direction. I need to be able to read this, and I need to be able to generate another signal with the same 3 variations. If it's any help, I don't care about polarity when reading, but I need to be able to write both polarities.

Just in case anyone is curious, this is my solution.

I don't need negative voltage for the output, I just need to be able to send electricity in both directions. So I connected the device to two pins. The two pins a both low. The direction then depends on which pin I raise. I added a resistor in series to adjust the voltage.

I haven't tried with the input yet. But with a rectifier made of four diodes that should be easy.