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.
Instead of configuring machine.I2C0, machine.I2C1, etc. statically,
allow the pins to be set using machine.I2CConfig. This will also
automatically configure the correct pin mode for each pin instead of
having to specify that manually.
Ayke van Laethem
deadprogram
Daniel Esteban
BCG