When UART is used for REPL and the MCU frequency is changed, the UART
has to be re-initialised. Besides that the UART may have to be recreated
after a frequency change, but with USB REPL this is not a problem.
Thanks to @HermannSW for spotting and providing the change.
Using the standard machine.freq().
The safe ranges tested were 10 and 12-270MHz, at which USB REPL still
worked. Requested settings can be checked with the script:
pico-sdk/src/rp2_common/hardware_clocks/scripts/vcocalc.py. At frequencies
like 300MHz the script still signaled OK, but USB did not work any more.
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>
