I've been debugging a Shelly [bluetooth
proxy](https://www.home-assistant.io/integrations/shelly/#bluetooth-support)
feature, which didn't like b-parasite's advertising. It swallowed it before proxying it to HA.
I compared to both ATC and the legacy b-parasite advertising
(pre-nrf-connect) and found it to be related to the
non-connectable/non-scannable settings. Until this PR, we were
mistankenly settings the advertising to scannable, although with no
scannable data. The Zephyr code that sets this parameter based on the
scannable data is [here](c0fcd35531/subsys/bluetooth/host/adv.c (L860)).
My bet is that some scanners like ESPHome are okay with this, but Shelly
is not. Either way, I believe this PR makes the advertisements more
compliant.
Previous, SW1 was too close to RST, making it difficult to press one
without pressing another. After changing its position, it was more
convenient to route SW1 to pin 10 on U1 - That's P0.30/AIN6 both on
nRF52840 (C) and nRF52833 (E) modules.
I previously used a basic 2N3906 and then changed its footprint to
SOT-23. This led to the wrong pin assignment.
This commit fixes it by using the correct symbol and footprint for it.
Note that the PCB layout still needs fixing.
This will enable us to transparently use different calibration for
different board revisions. The 2.0.0 revision changes the sensing
circuitry and will need its own coeffs.
In this commit, both models are run in parallel for debugging.
- Simplified the fast discharge circuit to use a single PNP BJT instead
of two NPN BJTs
- Swapped nRF52 module's footprint for one with larger pads
- Added a user button tied to P0.12 (same as Button 2 from [nrf52840_dk](https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrf52840_dk%2FUG%2Fdk%2Fhw_buttons_leds.html))
- Added a reset switch
These are only schematic changes - PCB layout is stale and needs to be
recreated.
