The ESP32 Ethernet Kit has only a single GPIO pin exposed to SAUL via
`saul_gpio`, but that GPIO doubles as PHY clock input when `esp32_eth`
is used. Hence, the `saul_gpio` dep should be optional and only kick
in when `esp32_eth` is not used.
- Rename all `arduino_pinmap.h` to `arduino_iomap.h`
- An empty `arduino_pinmap.h` that just includes `arduino_iomap.h`
is provided for backward compatibility
- Move all info from `arduino_board.h` into the new file as trivial
macros, so that they can also be used outside of sketches
- The new name reflects the fact not just pin mappings, but also
other I/O features such as PWMs are mapped
- Drop all `arduino_board.h`
- `arduino_board.h` and `arduino_iomap.h` now provide the exact
same information, just in a different format
- a generic `arduino_board.h` is provided instead that just
uses the info in `arduinio_iomap.h` and provides them in the
format the code in `sys/arduino` expects it
- Add fine grained features to indicate for mappings
- availability of mappings for analog pins, DAC pins, PWM pins,
UART devices, SPI/I2C buses to the corresponding RIOT
identification can now be expressed:
- `arduino_pins`: `ARDUINO_PIN_0` etc. are available
- `arduino_analog`: `ARDUINO_A0` etc. are available
- `arduino_pwm`: `ARDUINO_PIN_13_PWM_DEV` etc. are available
- `arduino_dac`: `ARDUINO_DAC0` etc. are available
- `arduino_uart`: `ARDUINO_UART_D0D1` or similar are available
- `arduino_spi`: `ARDUINO_SPI_ISP` or similar are available
- `arduino_i2c`: `ARDUINO_I2C_UNO` or similar are available
- mechanical/electrical compatibility with specific form factors
can now be expressed as features:
- `aruino_shield_nano`: Arduino NANO compatible headers
- `aruino_shield_uno`: Arduino UNO compatible headers
- `aruino_shield_mega`: Arduino MEGA compatible headers
- `aruino_shield_isp`: ISP header is available
This provides the groundwork to implement shield support as modules
that can rely on the I/O mappings, rather than having to provide a
configuration per board.
