I’ve got a CX-20 with a unique style APM2.52 that is two PCB’s stacked on top of each other, very similar (if not identical) to the PX4-FMU that has two PCB’s with one of them just an I/O board to give room for connecting up things like telemetry radio or power module. The I/O board then connects to the top board via rows of pins/connector on the right and left sides of each board (they plug into each other).
I’m trying to trace the UART telemetry connections from the UART socket to the pins plugged in and connected to the top “brain” board. There doesn’t appear to be anything between the UART plug for telemetry and those pins (as in no electronic components), which means a person COULD possibly tie into those telemetry connections via the appropriate pins coming off the I/O board and running to the main board with the processor on it.
Does anyone have any idea WHERE I might find those telemetry connections on the I/O at a spot OTHER than the UART connector?
Here’s the deal: I ended up burning off the traces (and more) getting the old UART socket off the I/O board and in so doing have made that connection unusable. I know those connections (RX, TX, VCC and GND) are eventually connected (or run to) the top PCB before getting routed on to the appropriate pins of the FC, so I’m sure you could potentially tap into them at that point where they connect to the top board (the row of pins that connect straight into the Main Board).
I think the pin-outs maybe just like the PX4, so maybe that’s a good place to start looking and something good to show to get the gist of everything I’ve described. So I’m attaching a photo of the PX4 I/O board with pin-out information to maybe help with ID’ing another telemetry connection point(s).