Step 4: Figure Out What's Going on Inside
The remote is powered by a 9V battery. My logic analyzer is only rated for 5 volts, so I want to check out what's going on with the DATA line before hooking it up to my logic analyzer.
If the signal on the DATA line is 9 volts, I have to do some tricks to get it down to 5V for the logic analyzer.
I connected an oscilloscope probe to the DATA line, and GND to the GND line on the remote. I set the trigger to two-ish volts and pushed a button. Out comes data! Sweet. This looks very hackable!
Turns out, the data line is only 3 volts. The distance between the horizontal dotted lines on the oscilloscope display is 2 volts.
The RF module looks like a pretty simple device, so I'll just assume that it can handle 5 volts as well as 3. The micro controller will be running at 5 volts.