Progress

This week I made the system fully energy-independent, able to power itself from its own battery. This involved a lot of tuning of the resistor values for the ADP5090 boost converter, to avoid accidentally setting the LiPo battery on fire. I also conducted some preliminary tests on how much energy we could harvest, and the results vastly exceeded my expectations. With a partially-overcast sky, the solar panel yielded about 0.6mA-1mA of current. This is already very impressive, consdering our quiescent draw of only 0.3mA. In direct sunlight, I observed up to 15mA of current from the panel, easily enough to charge the battery even with all the components active. This far exceeds any expectations we had of how much energy we could obtain, and gives us very strong evidence that we should use the panel.

Pacing

With most things working, we now just need to integrate the components into the firmware. This is taking longer than expected, but given that I have now completed my most time-intensive outstanding task (Robobuggy) I should much more time available to focus on finishing that up.

Planning

• Confirm that the motor is not nearly as viable as the solar panel
• Fix loading map tiles from the SD card