Xadow connectors aren't interchangeable

Well that wasted an embarrassing amount of time.  The xadow boards have flex cable connectors at each end so that you can daisy chain them.  I had the breakout board hooked up the wrong way, and spent several hours wondering why the A5 ADC input was showing up on the SCL pin.  Rotated it 180 degrees and now it works right.

Xadow analogRead

Updated: figured it out

I can't make sense of the pin mapping on this Xadow board to read analog values.  Note that analogRead() has funny behavior to start with.  But I looped through pins 18-29 (A0..A10 in pins_arduino.h), and the only one that came up with anything on analogRead() was 23, which seems to correspond with the pin labeled SCL on the breakout board.

I can't find anything that would explain how SCL/23/A5 relate to each other, or what other values would even be sensible to try.  There's a pin labeled A5 on the board, but pins_arduino.h #defines it as 23, and somehow that ends up on the pin labeled SCL.

At least I found one pin on which I can read the ADC.

Seeed Xadow "couldn't find a Leonardo" / "buffered memory access not supported" error when uploading

Spent an hour or two trying to figure out why I couldn't upload sketches from arduino to my Xadow board.  Turns out the serial port wasn't selected in Tools... Serial Port (even though /dev/ttyACM0 was the only option available).  Selected that and now it works great.