On Giga, the system will complain loudly if the frequency selected is too low
```<err> spi_ll_stm32: Unsupported frequency 400000Hz, max 120000000Hz, min 937500Hz```
Let's try to keep this at minimum or change when we'll be able to grab the same infor from a macro/API provided by zephyr

…iables

resolves #13

And: provides for c) option in zephyrproject-rtos#14

In particular, added another config option (config16) that is initialized at beginTransaction with same
settings as config except word size set to 16 instead of 8.

Also: updated begin() to call beginTransaction with default SPISettings, and the endTransaction, such that sketches that don't call beginTransaction output at the default settings.

Changed the header file private: to protected

The ringbuffer backing storage and the read buffer were the same buffer...
memcpy over the same location has some nasty implications

TODO: move to more complex APIs (like i2c_transfer) to properly implement stop bit

- Add support for I2C target mode.
- Fix buffer overflows, bad return values etc..

Signed-off-by: iabdalkader <i.abdalkader@gmail.com>

Signed-off-by: iabdalkader <i.abdalkader@gmail.com>

Signed-off-by: iabdalkader <i.abdalkader@gmail.com>

Use the ARG_UNUSED macro provided by Zephyr to mark function parameters
as intentionally unused to prevent compiler warnings.

Signed-off-by: Luca Burelli <l.burelli@arduino.cc>

Constructors should initialize members in the order they are declared in
the class definition.

Signed-off-by: Luca Burelli <l.burelli@arduino.cc>

- Arduino_LED_Matrix: fix packed attribute placement, add missing dependency
- Camera: fix pixel format check (formats are uint32_t, not pointers)
- Ethernet: fix float division literals
- SocketWrapper: hide deprecated warnings, fix signed/unsigned compare
- Wire: hide pedantic 'invalid offsetof' warning

Fixes zephyrproject-rtos#145