Refactors the zephyr build infrastructure to build MicroPython as a
cmake target, using the recently introduced core cmake rules.
This change makes it possible to build the zephyr port like most other
zephyr applications using west or cmake directly. It simplifies building
with extra cmake arguments, such as specifying an alternate conf file or
adding an Arduino shield. It also enables building the zephyr port
anywhere in the host file system, which will allow regressing across
multiple boards with the zephyr twister script.
Signed-off-by: Maureen Helm <maureen.helm@nxp.com>
Adds support for hardware i2c to the zephyr port. Similar to other ports
such as stm32 and nrf, we only implement the i2c protocol functions
(readfrom and writeto) and defer memory operations (readfrom_mem,
readfrom_mem_into, and writeto_mem) to the software i2c implementation.
This may need to change in the future because zephyr is considering
deprecating its i2c_transfer function in favor of i2c_write_read; in this
case we would probably want to implement the memory operations directly
using i2c_write_read.
Tested with the accelerometer on frdm_k64f and bbc_microbit boards.
This is to keep the top-level directory clean, to make it clear what is
core and what is a port, and to allow the repository to grow with new ports
in a sustainable way.
