Planchatek: (ra01sh or ht-ra62) + nice nano v2 promicro nrf52840 + batt% meter + cn3791 + xb8789d0 + attiny.

The xb8789d0 is responsible for cutting power to the promicro when the voltage drops to 2.9V. The attiny must be programmed to send a 200ms pulse every 24 hours to reset the promicro. The cn3791 is a solar charger module for the lithium-ion battery. The SMD (Surface-Mount Device) components are all 1206 size, and their value is noted on the board itself.

I added the attiny instructions in a pdf document. In the pcb I added two jumnpers to modify the behavior of the attiny one jumper is to put the attiny in test mode and reset in one minute and the other jumper doubles the times so that in test mode it resets in 2 minutes and in normal mode it resets in 24 hours instead of 12 without the jumper. In test mode the attiny pulses on other pins to show the remaining time through LEDs. More info in the pdf.

https://github.com/incre77/planchatek/