boot.py WiFi script

[abilio]

We want to share with you this boot.py script that we've been using internally in our development boards, in hope that you find it useful.

A short list of what it does:

• Configures the serial port at 115200 bauds (needed for Pymakr to connect over serial).
• Tries to connect to a list of known access points.
• If it doesn't find a known network, it fallbacks to access point mode, so you can connect straight to your board as it comes from the factory.

Please modify the first line to match your known networks.

Here is the script:

known_nets = [('home_ssid', 'home_password'), ('office_ssid', 'office_password')] # change this line to match your WiFi settings

import machine
import os

uart = machine.UART(0, 115200) # disable these two lines if you don't want serial access
os.dupterm(uart)

if machine.reset_cause() != machine.SOFT_RESET: # needed to avoid losing connection after a soft reboot
    from network import WLAN
    wl = WLAN()

    # save the default ssid and auth
    original_ssid = wl.ssid()
    original_auth = wl.auth()

    wl.mode(WLAN.STA)

    available_nets = wl.scan()
    nets = frozenset([e.ssid for e in available_nets])

    known_nets_names = frozenset([e[0] for e in known_nets])
    net_to_use = list(nets & known_nets_names)

    try:
        net_to_use = net_to_use[0]
        pwd = dict(known_nets)[net_to_use]
        sec = [e.sec for e in available_nets if e.ssid == net_to_use][0]
        wl.connect(net_to_use, (sec, pwd), timeout=10000)
    except:
        wl.init(mode=WLAN.AP, ssid=original_ssid, auth=original_auth, channel=6, antenna=WLAN.INT_ANT)

[gertjanvanhethof]

It doen't work when using a serial connection to the LoPy.
When I tried a wifi connection it's able to run and seems to work fine.

[gertjanvanhethof]

I try to run this script from Pymakr first but nothing happens and REPL window of LoPy becomes dead.
So I thought it has something to do with the script and removed the dupterm part (because it's already in my boot.py and not needed from Pymakr). Still the same result.
What could be the problem?

[LoneTech]

I think it's a little easier to use the dict directly:

known_nets = {
    # SSID : PSK (passphrase)
    'home_ssid': 'home_password',
    'office_ssid': 'office_password',
} # change this dict to match your WiFi settings

import machine
import os

# disable these two lines if you don't want serial access
uart = machine.UART(0, 115200)
os.dupterm(uart)

# test needed to avoid losing connection after a soft reboot
if machine.reset_cause() != machine.SOFT_RESET: 
    from network import WLAN
    wl = WLAN()

    # save the default ssid and auth
    original_ssid = wl.ssid()
    original_auth = wl.auth()

    wl.mode(WLAN.STA)

    for ssid, bssid, sec, channel, rssi in wl.scan():
        # Note: could choose priority by rssi if desired
        try:
            wl.connect(ssid, (sec, known_nets[ssid]), timeout=10000)
            break
        except KeyError:
            pass # unknown SSID
    else:
        wl.init(mode=WLAN.AP, ssid=original_ssid, auth=original_auth, channel=6, antenna=WLAN.INT_ANT)

Exercise left to do: try other recognized nets if association fails with one. Another possible feature is picking a less contended channel.