I'd like to reverse-engineer a certain 2-wire digital circuit. I'm looking for the cheapest possible logic analyzer. I don't know the exact frequency of the circuit, but it's sub-1MHz. (Likely in the range of 50kHz-500kHz.)
Obviously, I've heard about Bus Pirate, but I thought - hey, why not just use a serial port on my laptop? I have a UART-to-USB dongle based on a FT232-family chip, which is supposed to work with non-standard baud-rates, up to 1Mbd and beyond (depending which specific model you look up).
There are two challenges I can immediately see:
- Voltage. I assume a simple two-resistor voltage divider will suffice?
- Clock. Since I don't know the subject baud rate, I won't see the proper signal immediately. Maybe I could oversample initially and figure out the actual frequency from the observed signal?