asyncio limited subset on Trinket M0

[markhildreth]

I downloaded MicroPython (from here) onto my Adafruit Trinket M0, and was hoping to use asyncio. Unfortunately, I could not find the asyncio module.

MicroPython v1.20.0 on 2023-04-26; Trinket M0 with SAMD21E18A
Type "help()" for more information.
>>> import asyncio
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: module not found
>>> import uasyncio
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: module not found

However, I did find a _uasyncio module, although it was extremely limited in capability:

MicroPython v1.20.0 on 2023-04-26; Trinket M0 with SAMD21E18A
Type "help()" for more information.
>>> import _uasyncio as asyncio
>>> dir(asyncio)
['__class__', '__name__', '__dict__', 'Task', 'TaskQueue']

Am I missing something obvious? Does the port for this device not have a fully functional asyncio implementation?

[markhildreth]

So it looks like the asyncio module is indeed not being built. The manifest.py for samd21 boards seems to not include asyncio, whereas the esp32 board's manifest.py contains this line:

micropython/ports/esp32/boards/manifest.py

Line 2 in abb4469

include("$(MPY_DIR)/extmod/asyncio")

I tried to change this locally and build using a samd21 manifest that looked like this:

freeze("$(PORT_DIR)/modules")
include("$(MPY_DIR)/extmod/asyncio")

During build, however, I received this error message:

$ make -C ports/samd BOARD=ADAFRUIT_TRINKET_M0
(...snip...)
LINK build-ADAFRUIT_TRINKET_M0/firmware.elf
arm-none-eabi-ld: build-ADAFRUIT_TRINKET_M0/firmware.elf section `.text' will not fit in region `FLASH'
arm-none-eabi-ld: region `FLASH' overflowed by 5032 bytes
Memory region         Used Size  Region Size  %age Used
           FLASH:      193448 B       184 KB    102.67%
             RAM:        1880 B        32 KB      5.74%
make: *** [Makefile:201: build-ADAFRUIT_TRINKET_M0/firmware.elf] Error 1

I understand this as there just isn't enough flash memory to store the micropython installation that includes asyncio. Is my understanding correct?

[robert-hh]

Yes, you are right. You could increase the size for the code. Then, the file system will be smaller. The code size is a setting in mpcongigboard.mk, or you can define it at the command line during build. it is MICROPY_HW_CODESIZE.

[robert-hh]

At the moment it is set to 184k. so with 200k you get 26k more for code.

[jimmo]

However, I did find a _uasyncio module, although it was extremely limited in capability:

@markhildreth Just to follow up on this point -- _asyncio is a built-in helper to optimise some parts of asyncio, and probably we shouldn't include it if not freezing the actual asyncio module.

But it does mean that you could actually install asyncio to the filesystem.