Machine.reset() bricks board.

[zax71]

Hi! I've tried to follow the Raspberry Pi Foundation's web server guide to create an API on my ESP8266 but upon CTRL+C (it doesn't happen all the time) the board will lock up and become unresponsive to all actions (saving code, running code, reading new files, seeing serial console or erasing the flash with esptool) the one other time this hapened pluging the board in while holding reset and repeatidly trying to flash a new version of micropython worked but that doesn't seam to work this time.

Here's the code, it uses a lot of self-written modules but I don't think many are relevent here. Only the wifi.py serve function that is CTRL+C'd out of.

main.py

import shift_register_driver as driver
from machine import Pin
import time, machine, wifi

try:
    input("start?")
    ip = wifi.connect()
    connection = wifi.open_socket(ip)
    wifi.serve(connection)
except KeyboardInterrupt:
    machine.reset()

wifi.py

import network
import socket
from time import sleep
import machine
from secrets import secrets
from connection_handler import connection_handler

ssid = secrets["ssid"]
password = secrets["password"]

def connect():
    #Connect to WLAN
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    wlan.connect(ssid, password)
    while wlan.isconnected() == False:
        print('Waiting for connection...')
        sleep(1)
    ip = wlan.ifconfig()[0]
    print("Connected on " + ip)
    return ip

def open_socket(ip):
    # Open a socket
    address = (ip, 80)
    connection = socket.socket()
    connection.bind(address)
    connection.listen(1)
    return connection

def serve(connection):
    #Start a web server
    while True:
        client = connection.accept()[0]
        request = client.recv(1024)
        request = str(request)
        try:
            request = request.split()[1]
        except IndexError:
            pass
        connection_handler(request[1:])
            
        client.send("Fancy webpage")
        client.close()

[davefes]

Because I don't understand what happens in your main.py I would try:

import utime, wifi

try:
    ip = wifi.connect()
    connection = wifi.open_socket(ip)
    wifi.serve(connection)
except:
    print ('something went wrong')
    utime.sleep(10)

Sometimes I find it helpful to throw some 1 second delays in, ie between the three statements in the try

[jimmo]

Rather than implementing web servers from scratch, I wish more tutorials recommended using a proper web server. e.g. microdot https://github.com/miguelgrinberg/microdot

In general, it is almost impossible to truly "brick" a device. To recover your device it is not sufficient to just re-flash MicroPython because you also need to erase the filesystem. Using the erase_flash option to esptool before re-flashing the firmware to your esp8266 will solve this.

(On STM32/pyboard we have a way to trigger a filesystem reset without re-flashing, it would be good to add that to the other ports, especially rp2).

I'm not sure why your program is causing this to happen though. In general what @davefes suggests is a good idea. Another option is to add a time.sleep(1) to the start of your main.py so you always have a chance to Ctrl-C before your code starts running.

[zax71]

Thanks for the reply! For some reason leaving the board overnight fixed it? Anyway... I'm having a look at MicroDot but getting a MemoryError so according to their docs i need to compile thir files to .mpy to use them. Is that correct?

[robert-hh]

so according to their docs i need to compile thir files to .mpy to use them. Is that correct?

Yes, if it happens during import. Embedding the files into the firmware as frozen bytecode moves the code from RAM to Flash. That is even more efficient. During runtime, adding a gc.collect() into a main loop also helps to reduce heap fragmentation.