asyncio with multiple methods in micropython

Question

When I run the following code, it runs and print ("Listening, connect your APP to http://192.168.4.1:8080/") and waiting request as web server. During the web server mode, I want the LED to blink that's why I have applied asyncio.

However, unless it receives any request (which activates While True: loop in web server), LED does not respond. I have tried many ways but I could not find a way to toggle of LED during web server mode. You can see the comment regarding to await asyncio.sleep(20) in the code below:

import uasyncio as asyncio
from machine import Pin
import time

LED_PIN = 13
led = Pin(LED_PIN, Pin.OUT, value=1)

async def toggle():
    while True:
        await asyncio.sleep_ms(500)
        led.value(not led.value()) # toggling        

async def webServer(ipAddress):
    s = socket.socket()
    ai = socket.getaddrinfo(ipAddress, 8080)
    print("Bind address info:", ai)
    addr = ai[0][-1]
    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    s.bind(addr)
    s.listen(2)
    print("Listening, connect your APP to http://%s:8080/" % ipAddress)

    counter = 0
    # await asyncio.sleep(20) # !! if i applied await here, LED toggling 20 secs but web server does not accept any request because "while True" below is not activated during 20 secs.
    while True:
        res = s.accept()
        client_sock = res[0]
        client_addr = res[1]
        print("Client address:", client_addr)
        print("Client socket:", client_sock)

        req = client_sock.recv(1024)
        print("Payload: %s" % req.decode())
        client_sock.send(CONTENT % counter)
        client_sock.close()
        counter += 1
        print()

loop = asyncio.get_event_loop()
loop.create_task(toggle())
loop.create_task(webServer('192.168.4.1'))
loop.run_forever()

I want to know what is your embedded board name? Thanks in advance. — Benyamin Jafari
– Benyamin Jafari, Commented Jun 3, 2018 at 7:31

user4815162342 · Accepted Answer · 2018-02-01 16:55:58Z

2

Your webServer async function is not really async because it uses blocking IO. At a minimum you need to set the socket to non-blocking mode and use the socket operations provided by asyncio, or even better you should use asyncio.start_server to implement an asynchronous network server.

See the asyncio documentation or e.g. this answer for examples.

answered Feb 1, 2018 at 16:55

user4815162342

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5 Comments

Sunrise17 Over a year ago

loop.create_task(asyncio.start_server(handle_client, (ap_if.ifconfig()[0]), 8080)) & async def handle_client(reader, writer)

is solved the issue, Thanks. Only one issue, it is not overwriting the open connection. It enters web server mode only after reset. In sockets method, s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) was solving the issue, but i could not find a way in asyncio, how it can be corrected.

user4815162342 Over a year ago

@Sunrise17 Try passing reuse_addr=True to start_server. (This should be the default under POSIX OS-es.)

Sunrise17 Over a year ago

After 5 or 6 request as following below, from mobile App(URLSession.shared.dataTask(with: request)) to asyncio server installed on esp8266, server has timed out after a while.

Request path: / Content Length: 22 Request headers: Host: 0.0.0.0:10000 Content-Type: application/x-www-form-urlencoded Connection: keep-alive Accept: */* User-Agent: Chroma Accept-Language:  Content-Length: 22 Accept-Encoding: gzip, deflate Request payload: {"COLOR":[255,21,226]}

user4815162342 Over a year ago

@Sunrise17 Maybe you should ask a different question about this problem, with a minimal example etc...

Sunrise17 Over a year ago

It was related to asyncio server, in any case, i will open a new question about that.

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