Mini-LoRa V 1.2

[hk_iot]

Hello Charles,

I have a question regarind the Mini-LoRa v1.2 project. I am beginning and experimenting with LoRa and
I bought 10 PCBs of yours. Now, that I wanted to put parts on the boards I looked closer at the schematics
and a few questions came up.
a) the TPL5111 is connected to the atmega328 and I assume that the TPL wakes up the atmega (DRVN), the atmega does what it has to do, signals completion via DONE and goes to deep sleep until the TPL wakes it up again. Do you internally still use the 8sec watchdog timer or does the atmega wakes up from deep sleep because there is an edge on the pin DRVN and you therefore can extend the deep sleep time from 8sec to up to 2 hours saving a 900 waking up and going to sleep.
b) Why didn't you use a MOSFET in the line from the battery to the electronics which is driven by the TPL5111? In this case the electonics would not draw any current. Every 2 hours the TPL5111 via the MOSFET would give power, the atmega would do its thing, signal completion via DONE, go into a loop and wait for power off by the TPL5111. Whould that not be an idea?
c) I see the senors (BME280?) being powered all the time. Is this correct? Or how do you power the sensors during the deep sleep phases or the TPL5111 phases? Why is that? Also the eeprom I see powered all the time. Is this not a drain on the battery? Why did you decide to do it this way? What do I oversee? Is it possible to power the sensors via a pin of the atmega?

Thanks for the PCBs!

Regards,
Holger