A small footnote in the datasheet says that interrupt source numbers
correspond to the bit position in INTFLAG. We only need the RXC
interrupt for UART. In other words, ony the _2 interrupts (RXC is in the
2nd bit position) needs to be used for UART to work correctly.
In the future, more interrupts may be needed. They can then be added as
necessary.
I2C uses a hardcoded peripheral instead of referring to a specific
peripheral. In addition to that, it refers to the wrong SERCOM
(SERCOM3), which isn't used on any of the atsamd51 boards for I2C.
This commit lets the compiler know about interrupts and allows
optimizations to be performed based on that: interrupts are eliminated
when they appear to be unused in a program. This is done with a new
pseudo-call (runtime/interrupt.New) that is treated specially by the
compiler.
This commit does the same thing as
https://github.com/tinygo-org/tinygo/pull/597 but for samd51 series
chips. Pin mode and pad numbers are automatically calculated from pin
numbers, returning an error if no valid pinout is possible.
These all-caps constants aren't in the Go style, so rename it to
CPUFrequency (which is more aligned with Go style). Additionally, make
it a function so that it is possible to add support for changing the
frequency in the future.
Tested by running `make smoketest`. None of the outputs did change.
* machine/samd51: pin method cleanups.
- Use bit-math to select the group in Pin methods.
- Move Pin methods to atsamd51. They are not chip-specific, they apply to the whole atsamd51 family.
- Move the group/pin-id calculation into a helper method.
- Add a Pin.Toggle() method.
