WIFI connection script

[ctimmer]

After using a station connection script that kind of worked, I decided to clean it up to be more reliable. I wanted the script to always disconnect and automatically connect to "known" access point with an optional ifconfig parameter. My testing yielded a number of observations. The complete script is at the end of the post. Comments on improvements are most welcome. Curt

The 2 devices used for testing (Thonny):

MicroPython v1.20.0 on 2023-04-26; Raspberry Pi Pico W with RP2040
MicroPython v1.20.0 on 2023-04-26; ESP32S3 module with ESP32S3

Both devices produced similar results

Disconnecting

• I tried to come up with an "orderly" disconnect process
• If the connection was not active, nothing more was done
• Otherwise if it was connected an attempt was made to disconnect.
• Once disconnected, the active flag was set False

I had one problem with the pico. After the device was connected and sat idle for a few hours, it did not return False to wlan.isconnected(). The device did not respond to a ping. This only occurred once. For this reason a retry count was added.

def do_disconnect (wlan) :
    #---- Clear existing connection
    if wlan.active() :
        print ("Deactivate")
        if wlan.isconnected () :
            print ("Disconnecting")
            wlan.disconnect ()
            for retry_count in range (20) : # wait for dicconnect
                if not wlan.isconnected () :
                    break
                print ("waiting disconnect")
                time.sleep_ms (50)
        wlan.active(False)
        while wlan.active () :          # is this needed?
            print ("waiting inactive")
            time.sleep_ms (50)

Scanning

• scans always returned an empty list if the connection was not active or it was connected.
• scans do not always return the same AP list, sometimes returning an empty list. Multiple scans should to run.
• A priority value was included to provide for a preferred device. Signal strength could also have been used.

def do_wifi_scan (wlan) :
    ap_return = None
    do_disconnect (wlan)
    print ("Scanning...")
    wlan.active(True)
    #---- Do multiple scans because scans do not always return the same set of AP's
    for retry_count in range (25) :
        access_points = wlan.scan()
        for access_point in access_points :
            #print (access_point)
            ssid = access_point[0].decode ()
            if ssid not in SSID_LIST :
                continue
            if ap_return is not None :
                if ssid == ap_return ["ssid"] :
                    continue               # Already in AP return
                if SSID_LIST[ssid]["priority"] <= ap_return["priority"] :
                    print ("skipping:", ssid)
                    continue
            ap_return = {"ssid" : ssid}    # update AP return
            ap_return.update (SSID_LIST[ssid])
        if ap_return is not None \
        and retry_count >= 5 :
            break
    if ap_return is None :
        wlan.active(False)
    return ap_return

Connecting

• Fairly simple, wait for STAT_GOT_IP or a time out.
• A good connection usually occurred withing 3-4 seconds.
• The only 2 return values from wlan.status() were STAT_CONNECTING and STAT_GOT_IP. If a bad ssid or password were used the connection loop would always time out. Maybe different routers handle this differently.

def do_connect():
    #import network
    access_point = None
    wlan = network.WLAN(network.STA_IF)

    #---- get access point
    access_point = do_wifi_scan (wlan)
    if access_point is None :
        print ("No known access points found")
        return None

    #access_point["password"] = "Error" # for testing
    #access_point["ssid"] = "Error"     # for testing
    print('connecting to WIFI:', access_point["ssid"])
    if "ifconfig" in access_point :
        wlan.ifconfig (access_point["ifconfig"])
    wlan.connect (access_point["ssid"], access_point["password"])
    connect_max_ms = time.ticks_add (time.ticks_ms (), (CONNECT_TIMEOUT_SECONDS * 1000))
    while time.ticks_diff (connect_max_ms, time.ticks_ms ()) > 0 :
        time.sleep_ms (100)
        status = wlan.status ()
        #print ("status:", status)
        if status == network.STAT_CONNECTING :
            #print ("Connecting...")
            continue
        if status == network.STAT_GOT_IP :
            print('Connected:', wlan.ifconfig())
            return
        if status == network.STAT_WRONG_PASSWORD :
            print ("Invalid PASSWORD")
            return
        if status == network.STAT_NO_AP_FOUND :
            print ("Invalid SSID")
            return
        if status == network.STAT_WRONG_CONNECT_FAIL :
            print ("Connection FAILED")
            return
        print ("Unknown status:", status)
        # Shouldn't be here???
    print ("Connect TIME OUT")
    wlan.active(False)

Full Code

# Connect to know WIFI access point
# Feel free to steal any of this code, I did

import sys
import network
import time

CONNECT_TIMEOUT_SECONDS = 10
SSID_LIST = {
    "Guest" : {
        "password" : "Come on summer!" ,
        "priority" : 0
        } ,
    "myrouter" : {
        "password" : "mypassword" ,
        "ifconfig" : ('192.168.19.100', '255.255.0.0', '192.168.1.1', '8.8.8.8') ,
        "priority" : 10
        } ,
    "myotherrouter" : {
        "password" : "myotherpassword" ,
        "ifconfig" : ('192.168.19.100', '255.255.0.0', '192.168.1.1', '8.8.8.8') ,
        "priority" : 0
        }
    }

def do_disconnect (wlan) :
    #---- Clear existing connection
    if wlan.active() :
        print ("Deactivate")
        if wlan.isconnected () :
            print ("Disconnecting")
            wlan.disconnect ()
            for retry_count in range (20) : # wait for dicconnect
            #while wlan.isconnected () : # wait for dicconnect
                if not wlan.isconnected () :
                    break
                print ("waiting disconnect")
                time.sleep_ms (50)
        wlan.active(False)
        while wlan.active () :          # is this needed?
            print ("waiting inactive")
            time.sleep_ms (50)

def do_wifi_scan (wlan) :
    ap_return = None
    do_disconnect (wlan)

    print ("Scanning...")
    wlan.active(True)
    #---- Do multiple scans because scans do not always return the same set of AP's
    for retry_count in range (25) :
        access_points = wlan.scan()
        #print (access_points)
        for access_point in access_points :
            #print (access_point)
            ssid = access_point[0].decode ()
            if ssid not in SSID_LIST :
                continue
            if ap_return is not None :
                if ssid == ap_return ["ssid"] :
                    continue               # Already in AP return
                if SSID_LIST[ssid]["priority"] <= ap_return["priority"] :
                    print ("skipping:", ssid)
                    continue
            ap_return = {"ssid" : ssid}    # update AP return
            ap_return.update (SSID_LIST[ssid])
        if ap_return is not None \
        and retry_count >= 5 :
            break

    if ap_return is None :
        wlan.active(False)
    return ap_return

def do_connect():
    #import network
    access_point = None
    wlan = network.WLAN(network.STA_IF)

    #---- get access point
    access_point = do_wifi_scan (wlan)
    if access_point is None :
        print ("No known access points found")
        return None

    #access_point["password"] = "Error" # for testing
    #access_point["ssid"] = "Error"     # for testing
    print('connecting to WIFI:', access_point["ssid"])
    if "ifconfig" in access_point :
        wlan.ifconfig (access_point["ifconfig"])
    wlan.connect (access_point["ssid"], access_point["password"])
    connect_max_ms = time.ticks_add (time.ticks_ms (), (CONNECT_TIMEOUT_SECONDS * 1000))
    while time.ticks_diff (connect_max_ms, time.ticks_ms ()) > 0 :
        time.sleep_ms (100)
        status = wlan.status ()
        #print ("status:", status)
        if status == network.STAT_CONNECTING :
            #print ("Connecting...")
            continue
        if status == network.STAT_GOT_IP :
            print('Connected:', wlan.ifconfig())
            return
        if status == network.STAT_WRONG_PASSWORD :
            print ("Invalid PASSWORD")
            return
        if status == network.STAT_NO_AP_FOUND :
            print ("Invalid SSID")
            return
        if status == network.STAT_WRONG_CONNECT_FAIL :
            print ("Connection FAILED")
            return
        print ("Unknown status:", status)
        # Shouldn't be here???
    print ("Connect TIME OUT")
    wlan.active(False)

do_connect ()

[ctimmer]

Update to the pico problem above.

I had one problem with the pico. After the device was connected and sat idle for a few hours, it did not return False to wlan.isconnected(). The device did not respond to a ping. This only occurred once. For this reason a retry count was added.

This happened again so I added a loop limit to the disconnect and deactivate tests in the do_disconnect function. Both loops reached their limit.

Also, every scan I tried after returned an empty list. This was only resolved by powering off the device. Still don't know if this problem is limited to the pico device.

Curt