Am I doing something wrong? Have I discovered a bug? wifi.scan() doesn't seem to work as expected.

[wh33t]

So my apologies upfront if this whole discussion is bogus due to my noobness.

I am completely unfamiliar with ESP32 and Python ... I'm just trying to get my feet wet with the fundamentals.

I am using the Thing Plus C ESP32 from Sparkfun and the Thonny Editor.

I just want to power up the ESP32, and scan to see which wifi networks it can see.

This code will not produce any output when run.

# 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()

for i in available_wifi_networks:
    print (i[0] + " " + i[1])

However, I have noticed that if I declare the wifi object, set it's active status to false, sleep the device for 1 second, and then set it back to active it will work as expected and reliably so.

# wifi_test.py
import network
import time

# Create a station object to store our connection
wifi = network.WLAN(network.STA_IF)
wifi.active(False)  
time.sleep(1)
wifi.active(True)  

available_wifi_networks = wifi.scan()

for i in available_wifi_networks:
    print (i[0] + " " + i[1])

Is this ESP32 unit from Sparkfun faulty? Am I doing something wrong here?

Any and all help greatly appreciated. Cheers.

[davefes]

In your first block of code and after wifi.active(True) try this:

 #  seems more reliable to start with a fresh connect()
    if sta_if.isconnected():
        sta_if.disconnect()
        print('started in the connected state, but now disconnected')
    else:
        print('started in the disconnected state')

    utime.sleep(0.1)

[wh33t]

# wifi_test.py
import network
import time
import utime

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

#  seems more reliable to start with a fresh connect()
if wifi.isconnected():
    wifi.disconnect()
    print('started in the connected state, but now disconnected')
else:
    print('started in the disconnected state')

utime.sleep(0.1)

available_wifi_networks = wifi.scan()

for i in available_wifi_networks:
    print ("> " + str(i[0],"utf-8"))

Outputs

started in the disconnected state

[davefes]

Have been using f strings for the last month on the ESP32.

Hmm your whole email shows up in my Gmail message but not here??
Error line 13 often means that the error is in the line before.

[wh33t]

I'm totally new to python and esp32 so I'm not sure what the issue might be. Just created and ran this script.

# fstring_test.py
list = ['value1','value2']

print(f"{list}")

Output

%Run -c $EDITOR_CONTENT
Traceback (most recent call last):
File "", line 4
SyntaxError: invalid syntax

[davefes]

Maybe :

try:
     available_wifi_networks = wifi.scan()
    print(f'{available_wifi_networks}')
except OSError as error:
    print(f'{error}')    

[wh33t]

# wifi_test.py
import network
import time
import utime

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

try:
    available_wifi_networks = wifi.scan()
    for i in available_wifi_networks:
        print(f'{available_wifi_networks}')
except OSError as error:
    print(f"{error}")

Traceback (most recent call last):
File "", line 13
SyntaxError: invalid syntax

I don't think f strings are supported in micropython

If I remove the f strings

# wifi_test.py
import network
import time
import utime

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

try:
    available_wifi_networks = wifi.scan()
    for i in available_wifi_networks:
        print(available_wifi_networks)
except OSError as error:
    print(error)

Produces no output

[davefes]

Setting up a static IP also requires some hoops to jump through. I find the ESP32 a really useful device but there things happening down at a lower level that I wouldn't have a chance in sorting out.

I think there is a way to raise an issue from the thread itself. I haven't been bold-enough to do it.

[davefes]

@wh33t,

Could you try Glenn20's wifi.py and if that works properly I'll have a go at raising an issue?

[davefes]

On 2nd thought that is not going to work as scan on the WiFi network is not implemented.

[wh33t]

I am moving on from this issue, I will use the work around we've discovered.

I do think we should get this thread in front of anyone who works on the esp32 micropython port. It's obviously not a huge issue, but maybe we should let them decide whether or not it's a bug that needs fixing. Do you know how to get someone like that to see the thread?

[davefes]

Raised an issue

[Yanqi2023]

You should pressed En button，on the board。That can make wifi on。