It wasn't connected to the PC/USB at all, set using the test app I put together whereby the PC sends a packet via wifi to say set the reg/pin and the Arduino does the job.
That sketch looks great btw - should be included in the standard examples for the board!
It's the following, although the write doesn't "take" unless 5V/USB is not present, i.e. if it's plugged in, the register reverts to the default.
I'm starting to think that PA18 (from the schematic) is intended to be configured as an input. Pulled up by R21, and possibly then to ground via the USB ID pin (grounded for USB OTG cables), then the board could determine if USB OTG is intended.
My problem all along was that my boards did not have a resistor - R26 - present.
Hi Guys, I came across your discussion of the bq24195. A very nice read.
I have observed something I wanted to reach out and ask if others may have noticed.....
BTW, in case you are not aware, micros() does not increment during sleep because it uses the SysTick which is clocked by the cpu clock and is gated off during sleep.