The REV_A sensor worked and the last capacity measurements were within 3% of the loaded capacity. So thinks were working fine. But the REV_A board had a major bug on the footprint of the BMP180 pressure sensor I want to use for the Vario and Altimeter functions. So I tried to fix it with the solder iron. At the end I bricked it. One of the PDI lines goes under the microcontroller and this was the one having a short connection to the ground.

Since I proved everything possible with REV_A I went on and designed REV_B. It’s on GitHub right now.

News in REV_B

There are some new features:

• A button for programming
• A voltage reverence of 2048mV to the AREF pin of the XMEGA
• Some Ferrite Chip Beads and some small capacities at the IC VCC pins for steady working power

And it has a much smaller footprint of a board size under 35x35mm! So most components have the 0603 SMD package. This will be a challenge for the soldering I plan to do by hand.