Wifi scan procedure

[jancilliers]

Good day,

I build a circuit that scans for available APs in the area. The device powers up, does the scan, stores the info and powers down.

I'm struggling to get the AT+CWLAP command to work reliably.
When it works, it keeps on working during repeated attempts and returns the info of available APs in the area.
When it's not working the command only returns OK.

When it does not work after a reset, I set the CWMODE to 3 and back to 1 and that sometimes gets it to work.
It looks like it works a lot beter in mode 3 than in mode 1.

I'm using a ESP8266EX with SDK 1.5.0

I used to issue:
AT
ATE0
AT+CWMODE_CUR = 1
AT+CWLAP

The procedure that looks like it might work beter
AT
ATE0
AT+CWMODE_CUR = 3
AT+CWLAP

Could you please provide me the prescribe procedure to do a network scan?
Is there a minimum time to wait after power up before doing a scan?
Should it always work in mode 1?

Thank you,
Jan

[pratik]

Hello Jan,

I was able to reproduce this behavior using the AT firmware version that you specified (SDK 1.5).
It does not always return the networks available when the mode is changed.
And CWMODE = 1 and 3 are both prone to the same issue. Trying to join an AP (that does not exist) seems to clear the problem. Or enquiring currently joined AP also seems to clear the problem, as shown in the screenshot.

You may want to try another older firmware version such as the AT 0.40. The newer versions still seem to have it.
Meanwhile, I will try to find an explanation to this internally.
Could you please specify: what module are you using?

Thank you for taking the time to report this!

[jancilliers]

Hi Pratik,

Thanks for the prompt reply!!

We used the chip (ESP8266EX) directly in our design. With a Spansion 8Mbit flash and a Tai-saw 26Mhz crystal.

I'll give you suggestion to check the connected AP a try.
What seems to work at the moment is to set the mode to 3, wait 15 seconds and then scan.
I also repeat the scan 3 times. That seems to give me OK results.

I'm on holiday next week. So I'll try this when I'm back and give you feedback.

Thank you,
Jan.

[pratik]

Hi Jan,

I will keep this thread updated and let you know as soon as I have any information on this.
Thank you!

[ESP_Yuhao]

Hi Jan,
Could you please provide the detailed reproduce steps? I've reported your issue to Espressif engineer, who tried 50 times but still cannot reproduce.