BoSL Board V0.5 Debug

Issue List

ATMega issue

Description:
Get no response from BoSL Serial, looks like ATMega is dead. This happened twice on 2 boards.
Test:
The first time, the code used RTC for deep sleep. To exclude the RTC issue, the second
time used watchdog timer for deep sleep.

SIM7000 issue

Description:
When Sim7000 is power on, get no response from Sim7000.
Test:
Tried using different baud rates talk to Sim7000.
Tried keep sending "AT" to Sim7000.
None of the above method work.
After pressing reset button, sim7000 started to response.

Network register issue

Description:
Some boards cannot register to network.
Test:
Tested 6 boards by using same code, 4 of them cannot register to network.
Keep receiving "+CREG: 0,2", resetting sim7000 and re-connecting to battery won't fix it.

Debug history

6th Feb 2024

Yesterday(cloudy) tested 6 BoSL 0.5 boards, and found out 4 of them cannot register to network.
Today(clear day) tested the 4 "problematic" boards again, using the same sim card and same code.
2 of them are easy to register to network, no idea why, the weather?
1 of them cannot register to network at first, even tried "sendATcmd(F("AT+COPS=0"), "OK", 150000, 1);".
but after reconnecting to the battery 2 or 3 times, it was able to register to network.
There is still one board cannot register to network, reconnecting to the battery or await "AT+COPS" for 150s not work.