[ESP32 Micropython]Total noob here, I don't understand why this while loop won't run.

[wh33t]

I just went to turn the Wifi chip on, and scan to see which wifi networks are available.

    # wifi_test.py
    import machine
    import sys
    import network
    import utime
    import urequests

    # Create a station object to store our connection
    station = network.WLAN(network.STA_IF)
    station.active("up")

    while len(station.scan()) == 0:
        print "Waiting for Wifi..."
        
    print(station.scan())

I get this error:

Error:
Traceback (most recent call last):
  File "<stdin>", line 14
SyntaxError: invalid syntax

I am trying to use len(), because station.scan will output an empty list if the wifi is not ready (I think).

[buran]

If you are using python 3, this line print "Waiting for Wifi..." should be print("Waiting for Wifi...")

[wh33t]

Omg lol.

I see those brackets aren't optional like they are in PHP. Cheers!

[buran]

in python 2 print was a statement, in python3 it's a function and you need them for function call

[wh33t]

in python 2 print was a statement, in python3 it's a function and you need them for function call

Cheers. TY. I am not getting the result I expected, but it is not erroring now.

[rob101]

Not that I've used the libraries that you are using, but would while not station.scan(): be better? That way (in theory, least ways) you're testing for 'truthfulness'. Also, do you not have to update station.scan() in the while: loop? If not, how will any change in state be detected?

[wh33t]

Not that I've used the libraries that you are using, but would if not station.scan(): be better? That way (in theory, least ways) you're testing for 'truthfulness'. Also, do you not have to update station.scan() in the while: loop? If not, how will any change in state be detected?

Originally I tried while while !station.scan(): but I don't think that's valid python. I presumed wifi.scan() "forked" out into the background, and eventually wifi.scan() would return something. This seems to be pretty intermittent so maybe you are right, I have to continually update and check to see.

[wh33t]

Not that I've used the libraries that you are using, but would while not station.scan(): be better? That way (in theory, least ways) you're testing for 'truthfulness'. Also, do you not have to update station.scan() in the while: loop? If not, how will any change in state be detected?

I now have this code

# wifi_test.py
import network
import time

# Create a station object to store our connection
wifi = network.WLAN(network.STA_IF)
wifi.active(True)

available_wifi_networks = wifi.scan()

while len(available_wifi_networks) == 0:
    print("Waiting for wifi.scan() to return something...")
    time.sleep(1)
    available_wifi_networks = wifi.scan()
else:
    for i in available_wifi_networks:
        print (i)

It just keeps outputting

Output:
Waiting for wifi.scan() to return something...

[rob101]

I've tried the network library, but on my system (Debian based Linux distro) I'm getting builtins.AttributeError: module 'network' has no attribute 'WLAN', so I can't help; sorry.

[buran]

Originally I tried while while !station.scan(): but I don't think that's valid python.

It should be

while not station.scan():