It's sort of a cheap knock-off idea stolen from the Name that Ware on bunnies blog: I'm going to post one picture every month about a UART that I found on embedded hardware. Unfortunately I don't have much to offer in terms of a reward for whoever finds the true solution ;)
In any case, every month there are devices that I'm looking into either out of my own interest, or because the work at gpl-violations.org requires it. In most of them, you can find a UART to get to the u-boot / Linux serial console.
So here is the device that I just took apart earlier today:
The location of the UART pads was obvious, after looking at the PCB for a very short time. The entire unpopulated U1 footprint appeared suspiciously like a UART level shifter for true RS232 voltage levels:
- You can see two signals going directly to a small unpopualted3-pin header
- There are two other signals coming from somewhere under the main SoC
- There are capacitors (C440, C441) directly connected to the U1 for the charge pump