Fix Heltec Wireless Paper voltage

[pki791]

Added ADC_MULTIPLIER (default=1) to v3 board.
Added correct multiplier to ini of WP.

I think this is the easiest fix for the Heltec Wireless Paper not showing correct voltage.

[RichardPar]

Added ADC_MULTIPLIER (default=1) to v3 board. Added correct multiplier to ini of WP.

I think this is the easiest fix for the Heltec Wireless Paper not showing correct voltage.

seconded

[oltaco]

I think it would be cleaner to change

return (5.42 * (3.3 / 1024.0) * raw) * 1000; to return (ADC_MULTIPLIER * (3.3 / 1024.0) * raw) * 1000;

And add -D ADC_MULTIPLIER=5.42 to the other variants which use this board (heltec_v3 and heltec_tracker), and then you can use the true multiplier of 8.4 for the heltec wireless paper.

[ripplebiz]

Please change base branch to 'dev'

[Dutchy-79]

Got same problem but don't understand how to apply this fix

[Dutchy-79]

Just did a measurement. Battery 4.014v and app says 2,69v

Can I fix it myself for now or wait for a update?

[smokin74]

Got same problem but don't understand how to apply this fix

likewise!

[Dutchy-79]

Update 1.14.1 still the same 0% 2.57v

[liamcottle]

Hey, thanks for the PR! Closing out in favour of #2164