Instead of defining them separately for each board, define them once in
the chip definition and later simply use &sercomUART1 etc. to refer to
them. This is simpler and less error-prone.
I found two bugs while working on this:
- The P1AM-100 board mixed SERCOM 5 and SERCOM 3. It looks like SERCOM
5 was intended, based on the used pins.
- The Adafruit Matrix Portal appears to have configured the wrong
interrupt.
Unfortunately, I can't test these fixes. However, they make it clear
that such a change is important to avoid bugs.
I tested this commit on the PyBadge and the Circuit Playground Express.
Previously, the machine.UART0 object had two meanings:
- it was the first UART on the chip
- it was the default output for println
These two meanings conflict, and resulted in workarounds like:
- Defining UART0 to refer to the USB-CDC interface (atsamd21,
atsamd51, nrf52840), even though that clearly isn't an UART.
- Defining NRF_UART0 to avoid a conflict with UART0 (which was
redefined as a USB-CDC interface).
- Defining aliases like UART0 = UART1, which refer to the same
hardware peripheral (stm32).
This commit changes this to use a new machine.Serial object for the
default serial port. It might refer to the first or second UART
depending on the board, or even to the USB-CDC interface. Also, UART0
now really refers to the first UART on the chip, no longer to a USB-CDC
interface.
The changes in the runtime package are all just search+replace. The
changes in the machine package are a mixture of search+replace and
manual modifications.
This commit does not affect binary size, in fact it doesn't affect the
resulting binary at all.
