circuitpython/ports/minimal
David Grayson c046b23ea2 shared/runtime/pyexec: Don't allow Ctrl+C to interrupt frozen boot code.
Helps prevent the filesystem from getting formatted by mistake, among other
things.  For example, on a Pico board, entering Ctrl+D and Ctrl+C fast many
times will eventually wipe the filesystem (without warning or notice).

Further rationale: Ctrl+C is used a lot by automation scripts (eg mpremote)
and UI's (eg Mu, Thonny) to get the board into a known state.  If the board
is not responding for a short time then it's not possible to know if it's
just a slow start up (eg in _boot.py), or an infinite loop in the main
application.  The former should not be interrupted, but the latter should.
The only way to distinguish these two cases would be to wait "long enough",
and if there's nothing on the serial after "long enough" then assume it's
running the application and Ctrl+C should break out of it.  But defining
"long enough" is impossible for all the different boards and their possible
behaviour.  The solution in this commit is to make it so that frozen
start-up code cannot be interrupted by Ctrl+C.  That code then effectively
acts like normal C start-up code, which also cannot be interrupted.

Note: on the stm32 port this was never seen as an issue because all
start-up code is in C.  But now other ports start to put more things in
_boot.py and so this problem crops up.

Signed-off-by: David Grayson <davidegrayson@gmail.com>
2023-04-05 10:38:50 +10:00
..
Makefile minimal/Makefile: Set linker to $(CC). 2022-11-15 17:09:37 +11:00
README.md minimal/README: Update text to better describe what "make run" does. 2018-01-31 21:05:21 +11:00
main.c shared/runtime/pyexec: Don't allow Ctrl+C to interrupt frozen boot code. 2023-04-05 10:38:50 +10:00
mpconfigport.h minimal: Increase heap size for Linux builds. 2023-02-20 10:44:14 +11:00
mphalport.h all: Reformat C and Python source code with tools/codeformat.py. 2020-02-28 10:33:03 +11:00
qstrdefsport.h all: Add *FORMAT-OFF* in various places. 2020-02-28 10:31:07 +11:00
stm32f405.ld ports: Make new ports/ sub-directory and move all ports there. 2017-09-06 13:40:51 +10:00
uart_core.c unix,windows: Use STDIN_FILENO, STDOUT_FILENO macros where appropriate. 2020-03-25 00:59:05 +11:00

README.md

The minimal port

This port is intended to be a minimal MicroPython port that actually runs. It can run under Linux (or similar) and on any STM32F4xx MCU (eg the pyboard).

Building and running Linux version

By default the port will be built for the host machine:

$ make

To run the executable and get a basic working REPL do:

$ make run

Building for an STM32 MCU

The Makefile has the ability to build for a Cortex-M CPU, and by default includes some start-up code for an STM32F4xx MCU and also enables a UART for communication. To build:

$ make CROSS=1

If you previously built the Linux version, you will need to first run make clean to get rid of incompatible object files.

Building will produce the build/firmware.dfu file which can be programmed to an MCU using:

$ make CROSS=1 deploy

This version of the build will work out-of-the-box on a pyboard (and anything similar), and will give you a MicroPython REPL on UART1 at 9600 baud. Pin PA13 will also be driven high, and this turns on the red LED on the pyboard.

Building without the built-in MicroPython compiler

This minimal port can be built with the built-in MicroPython compiler disabled. This will reduce the firmware by about 20k on a Thumb2 machine, and by about 40k on 32-bit x86. Without the compiler the REPL will be disabled, but pre-compiled scripts can still be executed.

To test out this feature, change the MICROPY_ENABLE_COMPILER config option to "0" in the mpconfigport.h file in this directory. Then recompile and run the firmware and it will execute the frozentest.py file.