Pin numbers are now the MCU port numbers in the range:
PA0..PA31: 0..31
PB0..PB31: 32..63
PC0..PC31: 64..95
PD0..PD31: 96..127
Pins can be denoted by the GPIO port number, the name as defined in
pins.csv or a string in the form Pxnn, like "PA16" or "PD03".
The pins.c and pins.h files are now obsolete. The pin objects are part of
the AF table.
As result of a simplification, the code now supports using pin names or
numbers instead of pin objects for modules like UART, SPI, PWM, I2C, ADC,
pininfo.
Changes are:
- The pin-af-table-SAMDxx.csv file are moved to the mcu directories with
the name as pin-af-table.csv.
- The handling in Makefile and pin_af.c is simplified.
The pin af table is a representation of the MUX table from the data sheet.
It provides information for each pin about the supported device functions.
That information is needed by pin.irq, machine.ADC, machine.PWM,
machine.UART, machine.SPI and machine.I2C. For each of these, the table
tells for each pin, which device number, af number and pad number is
assigned. Using the table gives a straight, uniform access to the
information, where the benefit outweights the size of the table, which is
not that large.
The tables are MCU-specific. It is not required to tell for each board,
which and where each of the above devices is available. That makes addding
boards easy.
Note: The information for DAC and I2S was not included, since it affects
only a few pins.
