Add aliases for SDI, SDO and EN, so that pin names match the text on the
PCB to avoid confusion.
Also disable all pins from port B, because that package of SAMD21
doesn't have port B.
BHB needs better accuracy from the ADC readings. To avoid changing the ADC configuration for all boards or adding complexity to AnalogIn, I implemented a custom user module to allow the BHB to talk to the ADC in the way that it needs to. I'm open to other approaches here, but this seemed like the least invasive and complex option.
The newest version for the Stage library for PewPewM4 no longer contains
embedded graphics, which frees enough space in flash to enabled back
AnalogIO and also add USB_HID. There is still ~192 bytes left free.
If new additions to CircuitPython make it grow further, we can disable
USB_HID again.
We're moving towards a co-processor model and a Wiznet library is
already available.
New native APIs will replace these for chips with networking like the
ESP32S2 but they won't be these.
Not all boards have external flash or other components that make them
require 2.7V -- sometimes we can get considerably longer battery life
by decreasing this requirement.
In particular, pewpew10 and pewpew_m4 are powered directly from
battery, with no LDO, and should work fine down to 1.6V.
Since Actions passed on the previous commit, where this computed value
was checked against the specified value (if any), this is no net change,
except that we no longer need to specify it for particular boards or
ports.
Few peripherals are actually tested. However, USB, I2C and GPIO seem to work.
Most pins are silkscreened with the "PX00" style, so the board module
only includes the small number that are screened differently.
The default SPI, I2C, and UART are the ones on the EXT2 header. This is
arbitrary, but the I2C on this connector is shared with the on-board I2C
devices and the PCC header, making it the most versatile.
