It is often desireable to re-configure the pins of a bus back to GPIO mode,
either to save power when an external peripheral is turned off and current
would leak, or because a device may need a non-standard in-band signal to
be generated on the bus lines.
To serve those use cases, this patch introduces four new functions to the
I2C API:
- `i2c_init_pins()` equivalent to spi_init_pins(), restores I2C pin configuration
- `i2c_deinit_pins()` to switch the configuration of the I2C pins back to GPIO
mode and block access to the bus.
- `i2c_pin_sda()` to get the data pin for a given bus
- `i2c_pin_scl()` to get the clock pin for a given bus
Since it's unreasonable to expect having implementations for all platforms
already, those functions are only availiable when the periph_i2c_reconfigure
feature is availiable.
Applications should use FEATURES_REQUIRED += periph_i2c_reconfigure or
FEATURES_OPTIONAL if they want to make use of those functions.
i2c_release() should not have a return value, as:
- There is no reasonable error handling possible by the caller, so there is no
value in indicating success/failure via the return value to the caller
- There is no legitimate reason to fail *unless* an invalid I2C bus was released
or an I2C bus that was not previously acquired was released
--> This would indicate a bug in the code and should be tackled by an
assert()
The write_reg/s states a repeated start write is used but that is not how the i2c is implemeneted.
Most devices also only use a continuous write so the API should be changed to match implementation and the majority of sensors.
- added SPI_DEV and SPI_UNDEF macros
- made types and speed values overritable by CPU
- moved old device enum to dev_enums.h
- reformatted a little bit to comply to 80 char line length
- unify file/module @brief
- distinct @file section more visibly in source
- provide missing @brief's
- move module details/notes from file to module sections
- provide missing macro definition for building
