Pico W Wifi #15391

alanjob84 · 2024-07-02T10:31:58Z

alanjob84
Jul 2, 2024

Hello

Very new to the Pico/Micropython coding but I am running into an issue.
I have tried searching on here and other forums to no avail, but I don't believe I am the only one having this issue.

I am using the code below from the Raspberry pi website on my picoW and it works perfectly.
The issue I have is when wifi is lost the PicoW doesn't reconnect unless I physically power off and on the device.

Is there another piece of code to allow it to reconnect should the wifi disconnect?

import network
import socket
from time import sleep
from picozero import pico_temp_sensor, pico_led
import machine

ssid = 'NAME OF YOUR WIFI NETWORK'
password = 'YOUR SECRET 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(f'Connected on {ip}')
    return ip

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

def webpage(temperature, state):
    #Template HTML
    html = f"""
            <!DOCTYPE html>
            <html>
            <form action="./lighton">
            <input type="submit" value="Light on" />
            </form>
            <form action="./lightoff">
            <input type="submit" value="Light off" />
            </form>
            <p>LED is {state}</p>
            <p>Temperature is {temperature}</p>
            </body>
            </html>
            """
    return str(html)

def serve(connection):
    #Start a web server
    state = 'OFF'
    pico_led.off()
    temperature = 0
    while True:
        client = connection.accept()[0]
        request = client.recv(1024)
        request = str(request)
        try:
            request = request.split()[1]
        except IndexError:
            pass
        if request == '/lighton?':
            pico_led.on()
            state = 'ON'
        elif request =='/lightoff?':
            pico_led.off()
            state = 'OFF'
        temperature = pico_temp_sensor.temp
        html = webpage(temperature, state)
        client.send(html)
        client.close()

try:
    ip = connect()
    connection = open_socket(ip)
    serve(connection)
except KeyboardInterrupt:
    machine.reset()

peterhinch · 2024-07-04T09:54:06Z

peterhinch
Jul 4, 2024
Collaborator

Maintaining a connection requires asynchronous coding. An example is mqtt_as, a "resilient" MQTT client which detects outages and reconnects. In general outages can be either the WiFi connection or the remote resource to which you are connecting. You need to run a task which periodically polls the resource and detects an outage - if one occurs, the task makes repeated attempts to reconnect until it succeeds. The polling task tells the main communication task whether connectivity is currently available.

You might like to read my notes on writing resilient apps.

The best way to write such code is to use asyncio. See official docs and tutorial.

1 reply

alanjob84 Jul 4, 2024
Author

Hello,
Thank you for replying.
I was looking into asyncio and started coding for it but ran into another problem.
When I force disconnect the picow from the ap or turn the ap off the pico still thinks it connected.
I then wrote another code that uses threading to run a uping in a second thread.
But for some reason wifi and uping wont work while in the second thread.
So I think I need to write a asyncio and have a uping in it to keep the connection alive.
Thank you again for your input.
Alan

mendenm · 2024-07-04T10:47:03Z

mendenm
Jul 4, 2024

Here is a block of code from a fairly high-reliability network device I built. Note the keep_net_alive() async function. I had the vague opinion that running an occasional uping.ping() to the WiFi host also tended to keep things alive, although that is pretty close to superstition.

#test microdot

from microdot_asyncio import Microdot
import asyncio
import uping

app = Microdot()

@app.get('/')
async def index(request):
    #print(request.client_addr, request.body)
    return '''
<html>
<head> </head>
<body>
<h1>Hello, World!</h1>
</body>
</html>
''', 200, {'Content-Type': 'text/html'}


@app.get('/set_time')
async def set_time(request):
    #print(request.client_addr, request.body)
    import ntptime
    ntptime.timeout = 10
    ntptime.settime()
    from machine import RTC
    rtc = RTC()
    return f'''
<html>
<head> </head>
<body>
<h1>{str(rtc.datetime()):s} UTC</h1>
</body>
</html>
''', 200, {'Content-Type': 'text/html'}


@app.get('/index/')
def index_files(request):
    import os
    top = '''
<html>
<head> </head>
<body>
<ol>
'''
    vals = '\n'.join( "<li>"+x+"</li>" for x in sorted(os.listdir("/timelogs/")) )
    
    bot = '''
</ol>
</body>
</html>
'''
    return top + vals + bot, 200, {"Content-type":"text/html"}

@app.get('/timelogs/<string:filename>')
def handle_file(request, filename = None):
    from microdot_asyncio import send_file
    args = request.args
    delete = 'delete' in args and args['delete'][0] == '1'
            
    try:
        if delete:
            import os
            os.remove('/timelogs/' + filename)
            return 'removed', 200, { 'Content-Type':'text/plain' }
        else:
            return send_file('/timelogs/' + filename, content_type = 'text/plain',
                 extra_headers = {'Content-Disposition':  'attachment'}
                         )
    except OSError:
        return "File not found:" + filename, 404, {}
    
from detect_power_line import doit_events, current_status

@app.get('/status')
def index_files(request):
    import os
    from machine import RTC
    rtc = RTC()
    
    top = '''
<html>
<meta charset="UTF-8">
<style>
table {
  border-collapse: collapse;
}
th, td {
  padding-right: 5px;
  padding-left: 5px;
  padding-top: 5px;
}
th {
  text-align: center;
  border: 2px solid black;
}
td {
  text-align: right;
  border: 1px solid black;
}
</style>
'''
    head = '''
<head> Date: {0:04d}-{1:02d}-{2:02d} {4:02d}:{5:02d}:{6:02d}</head>
'''.format(*rtc.datetime())

    body = '''
<body>
<table>

<tr>
<th> time / ms </th>
<th> ADC </th>
<th> IQ mag / mLSB </th>
<th> I </th> <th> Q </th> <th> φ/° </th>
<th> RMS / LSB </th>
<th> Δt / s </th>
</tr>
'''
    
    bot = '''
<table>
</body>
</html>
'''

    vals = '\n'.join(
        [ '\n'.join(['<tr>'] + ["<td>" + x+ "</td>" for x in r.split()] + ['</tr>'])  for r in current_status ]
    )
    
    return top + head + body + vals + bot, 200, {"Content-type":"text/html", "Refresh":"10"}

nic = None

netdict = json.load(open("networks.json","r"))

async def keep_net_alive(verbose):
    global nic
    import network
    last_status = -1
    while nic != "STOP":
        stat = nic.status() if nic is not None else -4
        if stat < 0:
            if verbose and nic is not None: print("no net:", nic.status(), nic.ifconfig())
            if nic is not None: nic.active(False)
            last_status = stat
            #network hard crashed...
            network.hostname("powerline_pico")
            network.country('US')
            #ap = network.WLAN(network.AP_IF)
            #ap.active(False) #turn off any AP interface activity
            nic = network.WLAN(network.STA_IF)
            nic.active(True)
            await asyncio.sleep(1)
            if verbose: print("attempted activation:", nic.status())
        elif last_status < 0 or not nic.isconnected(): #alive, but not connected
            nets = nic.scan()
            if verbose: print("found", [str(x[0],'utf8') for x in nets])
            for net in nets:
                netname = str(net[0],"utf8") #might be bytes from NIC
                if netname in netdict:
                    nic.disconnect() #start  over here
                    nic.active(False)
                    await asyncio.sleep(1)
                    nic.active(True)
                    nic.connect(net[0], netdict[netname])
                    while nic.status() > network.STAT_IDLE and nic.status() != network.STAT_GOT_IP: 
                        await asyncio.sleep(1) #check again later
                    if verbose: print("connected to", str(net[0], 'utf8'), nic.ifconfig(), nic.config('hostname'))
                    break

            nic.config(hostname  = "powerline_pico")
            last_status = nic.status()
            await asyncio.sleep(1) #check again later
        else:
            config =  nic.ifconfig()
            uping.ping(config[-1], count = 1)
            if verbose: print("on net:", nic.status(), nic.ifconfig())
            await asyncio.sleep(5)            

async def set_initial_time(log):
    import ntptime
    while 1:
        try:
            if log: print("setting time")
            ntptime.timeout = 5
            ntptime.settime()
            if log:
                from machine import RTC
                rtc = RTC()
                print("set time to:", rtc.datetime())
            break
        except OSError as e:
            print("oops", str(e))
            await asyncio.sleep(5)
            pass #just keep looping until it happens
    
async def doit(log = False, startidx = 0):
    global nic
    #print("starting line monitor")
    net_monitor = asyncio.create_task(keep_net_alive(log))
    
    time_init = asyncio.create_task(set_initial_time(log)) #should return after time set, when network is up
    
    line_monitor = asyncio.create_task(doit_events(log = log))
    #print("starting web  server")
    web_server = asyncio.create_task(app.start_server(host='0.0.0.0', port=5000, debug = False, ssl = None))
    await line_monitor
    app.shutdown()
    nic = "STOP"
    await net_monitor
    
if __name__=="__main__":
    asyncio.run(doit(log=True))

1 reply

alanjob84 Jul 4, 2024
Author

Hello.
Wow, that's a lot more complex than mine.
I did look into asyncio and started coding for it but ran into problems.
When I force disconnect the picow from the ap or turn the ap off the pico still thinks it connected.
I think uping with asyncio seems to be the way to go.
Thank you again for your input.
Alan

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Pico W Wifi #15391

alanjob84 Jul 2, 2024

Replies: 2 comments · 2 replies

peterhinch Jul 4, 2024 Collaborator

alanjob84 Jul 4, 2024 Author

mendenm Jul 4, 2024

alanjob84 Jul 4, 2024 Author

alanjob84
Jul 2, 2024

Replies: 2 comments 2 replies

peterhinch
Jul 4, 2024
Collaborator

alanjob84 Jul 4, 2024
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mendenm
Jul 4, 2024

alanjob84 Jul 4, 2024
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