asynchronous wlan scans

[sjdh]

Hi

I am working on a a WiFi localization project.
With the excellent uasyncio module, I log data from several sensors including gps.
In addition I want to log wireless network scan's. Is it possible make scan's asynchronously? Now it is blocking the rest of the functions.

Also I'd like to have a look at the code for wlan scanning to get a better understanding.
Where is the source located? I am using the ESP32.

[jcw]

I don't know how it works, but it looks like the code you're after can be found here:

https://github.com/micropython/micropyt ... #L439-L473

[sjdh]

Thanks jcw. That looks like the part where the scanning happens.

For the esp8266, this ardruino example from shows asynchronous scanning for networks.
https://arduino-esp8266.readthedocs.io/ ... mples.html

Code: Select all

  
  
  // trigger Wi-Fi network scan
  if (currentMillis - lastScanMillis > SCAN_PERIOD)
  {
    WiFi.scanNetworks(true);
    Serial.print("\nScan start ... ");
    lastScanMillis = currentMillis;
  }

  // print out Wi-Fi network scan result uppon completion
  int n = WiFi.scanComplete();
  if(n >= 0)
  {
    Serial.printf("%d network(s) found\n", n);
    for (int i = 0; i < n; i++)
    {
      Serial.printf("%d: %s, Ch:%d (%ddBm) %s\n", i+1, WiFi.SSID(i).c_str(), WiFi.channel(i), WiFi.RSSI(i), WiFi.encryptionType(i) == ENC_TYPE_NONE ? "open" : "");
    }
    WiFi.scanDelete();
   

How would you write equivalents for WiFi.scanNetworks() and WiFi.scanComplete() for micropython?

[jcw]

Dunno, sorry.

[jimmo]

How would you write equivalents for WiFi.scanNetworks() and WiFi.scanComplete() for micropython?

There's a couple of options here --

1. Make modnetwork "asyncio-aware". i.e. scan() would be something you could use with "async for"

Code: Select all

async def do_scan():
  async for result in sta_if.scan():
    handle(result)

I don't think there are any examples of this currently in the firmware. Although it would be cool to see more stuff starting to work that way, and I'd love to see asyncio become a more fundemental part of most of the core APIs (e.g. machine). e.g. "await pin" to wait for a pin edge.

2. Make modnetwork irq/callback-based. This is what we did in modbluetooth.

Code: Select all

def handler(event, data):
  if event == IRQ_SCAN_RESULT:
    handle(data)
  elif event == IRQ_SCAN_COMPLETE:
    handle(None)

ble.irq(handler)
ble.gap_scan(...)

However there's currently no way to then make this into something you can use from asyncio (but it's being actively worked on right now, see https://github.com/micropython/micropython/pull/6125/ and https://github.com/micropython/micropython/pull/6106/ ).

[sjdh]

Thanks

Code: Select all

async def do_scan():
  async for result in sta_if.scan():
    handle(result)

This is what I would love to use. It is not there, but how about your toy example

[/quote]

t would be cool to see more stuff starting to work that way, and I'd love to see asyncio become a more fundemental part of most of the core APIs (e.g. machine). e.g. "await pin" to wait for a pin edge.

how would you design this? are there any obstacles?

More general, if you want to get started with development of c code for micropython, where can you start? Are there perhaps some warm-up examples to get something very basic done? Or some other resources?