How can I use core 1 to assign work to core 0

[GM-Script-Writer-62850]

Note that CPU cores are [0,1] running on a W5500_EVB_PICO

I would like to have core 1 doing time sensitive polling work using _thread

When core 1 finds work I want to send it to core 0 where core 0 is using uasyncio, i know _thread is buggy so i want to keep it simple core running on core 1 and let core 0 do the fancy stuff

I was trying to use interrupts on core 0 and i am having a lot of issues with switch bounce and EMI, so i am just going to use polling ever ms, dealing with switch bounce is one thing but EMI...

[GM-Script-Writer-62850]

Surprised I do not have a reply yet, so i have this dumb hack solution, I really hope I do not have a EMI issue with this case that will SUCK...

Sadly this is still a interrupt so it will stop other work from being done, should only be a issue if core 0 is reading a DHT22 sensor... but since the results are not time sensitive that is not a issue if i have to re-poll the sensor once and a while

but i can store a assignment in a variable toggle the pin triggering the interrupt then core0 will do the work i want when i want it done

from machine import Pin
from _thread import start_new_thread as newThread
from time import sleep

p=Pin(0,Pin.OUT,value=0)# A spare/NC pin

def work(pin):
	print('hi')

p.irq(handler=work, trigger=Pin.IRQ_RISING | Pin.IRQ_FALLING)

def core1():
	while True:
		sleep(1)
		p.toggle()

newThread(core1,())

while True:
	print("waiting")
	sleep(1)

[cve2022]

I would like to have core 1 doing time sensitive polling work using _thread

Hi, I have a similar(ish) question, take a look at #10371 .

I still have some tests to do related to the aforementioned discussion, but according to my understanding, I will have to leave the core 0 for the realtime stuff and core 1 will do other not time critical tasks. I think it should work for your use case as well and you will need to use some IPC resource for the task in core 0 to send whatever it collected to the task/process/coroutine running on core 1 for post processing.

HTH.

[GM-Script-Writer-62850]

hold up a second the PICO has SMT? i though it was 2 cores 2 threads, not 2 cores 4 threads

[cve2022]

hold up a second the PICO has SMT? i though it was 2 cores 2 threads, not 2 cores 4 threads

Nope. With _thread you have only two threads, one thread per core.

You may find uasyncio of interest. It simulates multithreading by the use of coroutines. There is a thorough tutorial on it: https://github.com/peterhinch/micropython-async.

In the case of RP2, I believe you can combine _thread and uasyncio to have the benefit of using the two available cores of the RP2 and the concurrency capabilities of uasyncio to code a fairly complex application. Depending on your systems requirements, you may find asyncio more than sufficient though.

HTH.

[GM-Script-Writer-62850]

i am somewhat familiar with uasyncio and do intended to use it, i just also make use of thread, i know how to make use of sleep and await and i think i know how to use yield

i have not tired to use it on core 1, only used it on core 0 so far, hopefully it is not bugged on _thread and i can use it on both cores

[jimmo]

To answer the general question -- if you want to make the second core trigger asyncio tasks in the first core, then asyncio.ThreadSafeFlag is what you need.

i know _thread is buggy so i want to keep it simple core running on core 1 and let core 0 do the fancy stuff

@GM-Script-Writer-62850 can you provide a reference or background for this? I feel like I keep hearing this repeated but haven't been able to get anyone to demonstrate a repro for this (since we fixed stuff several months ago).

hold up a second the PICO has SMT? i though it was 2 cores 2 threads, not 2 cores 4 threads

Nope. With _thread you have only two threads, one thread per core.

Just to clarify because despite the "Nope." from @cve2022 it seems like you're agreeing. On the rp2040 there is two cores, and one thread per core (i.e. you may optionally create one additional thread).

[GM-Script-Writer-62850]

Wait a min if I can only use uasync on one core and have it on core 1, if i use uasyncio.createTask on core 0 will it run on core 1

[peterhinch]

No. uasyncio.createTask must run on the same core as uasyncio.

[jimmo]

To clarify this -- create_task will mutate asyncio's internal state. As above, asyncio is completely thread-oblivious, so this mutation can race other internal operations (such as scheduling).

If you have asyncio running on one core, and you want to trigger something from a different core (or context, such as IRQ) you must use ThreadSafeFlag (or something built on that).
(In more detail: you could of course just set a global variable and poll that from your asyncio code, but this is less efficient than using ThreadSafeFlag)

FWIW, Python has https://docs.python.org/3/library/asyncio-task.html#asyncio.run_coroutine_threadsafe which is something we might consider adding.

[peterhinch]

@GM-Script-Writer-62850 To implement what you want you need something like this:

import uasyncio as asyncio
tsf = asyncio.ThreadSafeFlag()  # Shared global
async def run_on_demand():
    while True:
        await tsf.wait()
        # Run payload code

Code in the other thread issues tsf.set() when it wants the payload to run.

[GM-Script-Writer-62850]

Thanks, that was something i wanted to know how to use, do i need to use a tsf.unset() or is tfs.set() consumed by tsf.wait()