Version 1.1 of the main daughter board arrived a few days ago. I ordered it from DirtyPCBs a while back but due to the Chinese holiday it took a little longer than usual to turn up. The primary goal for V1.1 was to cleanup the various mistakes from V1.0, and also to add an I2C multiplexer chip. This provides two useful functions: 1 - it provides some level of protection to the Raspberry Pi when I'm messing with I2C devices in the ROV, and 2 - it allows me to handle address conflicts by placing I2C devices with the same address on different buses. The V1.0 had an address conflict when I tried to add the water pressure sensor - the address clashed with the humidity/pressure/temp sensor. In V1.1 I moved the latter sensor to it's alternate address, but I wanted to add some extra safety for the future.

The new board, mounted on the Pi with the Tenda board, can be seen below and - amazingly - all seems to work.