Sensor module - shrinking

 After finishing the initial design for the wireless sensor modules I realized the placement of the connectors was far from optimal. Having the sensor connector in the middle of the board would mean I wouldn't be able to attach a socket and stick a sensor right in; I'd rather have the sensor connector on a far end of the board.
I also wanted the nRF module to stack onto the board, but as it turned out, I had placed the connector upside down, so the nRF module would stick out instead of hang over the board. So time for revision 2!

I decided to place the ICSP header on the side of the board, just like the USBASP dongles. A few components have moved to the back of the board, including the 3.3V regulator and pull down resistor for the sensor. All in all the board has shrunk about 20% in length, lowering the cost even further, although adding a shrouded connector offsets that saving... Total component cost is now down to less than $2 excluding the sensor and nRF module.

The outline shows how the nRF module is positioned on top of the board, the extra line indicates where the antenna area starts. I tried to keep the overlap of the board and antenna area to a minimum.

Meanwhile I've started programming some bits and pieces, trying out a few new techniques to keep the memory footprint to an absolute minimum. It's going to be a challenge to fit everything in 1 KiB of ROM (just 512 instructions). Interestingly enough, the code is a mix of assembler and C++ templates.