Boron hibernate behaviour on USB unplug

Firmware
#1

I’ve noticed some unusual behaviour when I unplug my Boron from USB while it has a battery connected and while it is in hibernation mode.

Code is here if you want to look:

I have set up a battery charge mode, which shows battery state while charging on an epaper display. When charging is complete, it shows a battery charged image and then goes to hibernate mode. This seems to work properly.

I want to be able to unplug it and have it stay in hibernate mode until I push a power button, and then when I push the button I want it to start from a reset state.

However, when I unplug the USB cable, the Boron resets. Will a Boron always reset on USB connect and disconnect?

I currently have nothing connected to the pin I have assigned as the wake up pin.

There’s a second problem in that this line in my code isn’t working right:

 if (System.powerSource() == POWER_SOURCE_BATTERY)

even when it is on battery power only, and the battery is directly connected to the ground and Li+ pins (no ammeter in series), that line seems to fail. I can’t debug this, because connecting the debugger and USB cable would make this line not do what I want.

The battery I’m using to test is this 18650:

It’s not a battery problem, I tested that cell in a flashlight and it works just fine for several hours.

Any suggestions would be appreciated,

Thanks!

#2

Another problem I noticed:

~21 seconds after it goes into hibernate, it resets. This occurs both on USB and battery power, and with the wakeup pin both unconnected and externally tied to ground.

#3

I’ve solved part of it. When I disable system thread, it stays in hibernate and doesn’t reset every ~20 seconds.

Is there a way to get hibernate to work properly while using system_thread? I can work around not having it, but I have some long delays, and using multithreading allows me to use delay() without losing the network connection (or doing a big awkward workaround with timers and interrupts).

I still don’t know why it resets when USB is unplugged, or why the line

 if (System.powerSource() == POWER_SOURCE_BATTERY)

does not work

#4

I solved the hibernate problem by removing the Cellular.off() call. Now hibernate works properly.

I have done some more investigation, and the power source problem is a bug in DeviceOS.

I still don’t know why my application resets when I unplug USB.