The PIO state machines on the RP2040 have 4 word deep TX and RX FIFOs.  If
you only need one direction, you can "merge" them into either a single 8
word deep TX or RX FIFO.

We simply add constants to the PIO object, and set the appropriate bits in
`shiftctrl`.

Resolves #6854.

Signed-off-by: Tim Radvan <tim@tjvr.org>

There were a few changes that had broken this example, specifically
2cdf1d25f59409b6130c0e8b6cf50300aed2d7e6 removed file.c from ports/unix.
And (at least for MacOS) mp_state_ctx must be placed in the BSS with
-fno-common so it is visible to the linker.

Signed-off-by: Santeri Paavolainen <santtu@iki.fi>

It's a bit of a pitfall with user C modules that including them in the
build does not automatically enable them.  This commit changes the docs and
examples for user C modules to encourage writers of user C modules to
enable them unconditionally.  This makes things simpler and covers most use
cases.

See discussion in issue #6960, and also #7086.

Signed-off-by: Damien George <damien@micropython.org>

examples/usercmodule/micropython.cmake:

Root micropython.cmake file is responsible for including modules.

examples/usercmodule/cexample/micropython.cmake:
examples/usercmodule/cppexample/micropython.cmake:

Module micropython.cmake files define the target and link it to usermod.

Signed-off-by: Phil Howard <phil@pimoroni.com>

The "word" referred to by BYTES_PER_WORD is actually the size of mp_obj_t
which is not always the same as the size of a pointer on the target
architecture.  So rename this config value to better reflect what it
measures, and also prefix it with MP_.

For uses of BYTES_PER_WORD in setting the stack limit this has been
changed to sizeof(void *), because the stack usually grows with
machine-word sized values (eg an nlr_buf_t has many machine words in it).

Signed-off-by: Damien George <damien@micropython.org>

This was adapted from the `pio/uart_rx` example from the `pico-examples`
repository:
https://github.com/raspberrypi/pico-examples/blob/master/pio/uart_rx/uart_rx.pio

It demonstrates the `jmp_pin` feature in action.

Signed-off-by: Tim Radvan <tim@tjvr.org>

This commit adds a new port "rp2" which targets the new Raspberry Pi RP2040
microcontroller.

The build system uses pure cmake (with a small Makefile wrapper for
convenience).  The USB driver is TinyUSB, and there is a machine module
with most of the standard classes implemented.  Some examples are provided
in the examples/rp2/ directory.

Work done in collaboration with Graham Sanderson.

Signed-off-by: Damien George <damien@micropython.org>

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

This widens the characteristic/descriptor flags to 16-bit, to allow setting
encryption/authentication requirements.

Sets the required flags for NimBLE and btstack implementations.

The BLE.FLAG_* constants will eventually be deprecated in favour of copy
and paste Python constants (like the IRQs).

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

Add working example code to provide a starting point for users with files
that they can just copy, and include the modules in the coverage test to
verify the complete user C module build functionality.  The cexample module
uses the code originally found in cmodules.rst, which has been updated to
reflect this and partially rewritten with more complete information.