OSError: scan failed

All ESP8266 boards running MicroPython.
Official boards are the Adafruit Huzzah and Feather boards.
Target audience: MicroPython users with an ESP8266 board.
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lalondesteve
Posts: 3
Joined: Thu Jun 11, 2020 4:53 pm

OSError: scan failed

Post by lalondesteve » Sun Dec 06, 2020 8:07 am

Hello gents,

I've been lurking for a while, first time poster.
I have an issue that seems unusual. I have a few 8266 boards around the place, some NodeMCU and some D1.
All of them (but one that I killed in a 5v vs 3.3v incident), I connected them to my rpi, would check that AT commands work, flash micropython binaries, connect to serial tty, connect them to wifi and enable webrepl. All done the same way in a few minutes without issues.

But today I received four more D1 mini (v3.0) and so far, three out of the four seem to have the same issue (I left one sealed in its bag). When I connect them, I don't see the AP essid from my computer nor my phone. When I log in them, everything works fine, but if I enable STA and do a scan (AT+CWLAP), I don't see the list of wifi, but only "OK".

I installed micropython on two of them and same behaviour. But now, when I scan for wifi, I get :

Code: Select all

>>> sta.active(True)
#6 ets_task(4020f560, 28, 3fff9ed0, 10)
>>> sta.scan()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OSError: scan failed
Is there any further testing I can do to prove them faulty or any way I can fix them?

Thank you very much,

S

EDIT: I'm flashing

Code: Select all

esp8266-20200911-v1.13.bin
Last edited by lalondesteve on Mon Dec 07, 2020 4:09 am, edited 2 times in total.

lalondesteve
Posts: 3
Joined: Thu Jun 11, 2020 4:53 pm

Re: OSError: scan failed

Post by lalondesteve » Sun Dec 06, 2020 3:08 pm

Update :
- I tried flashing with esptool v.3 and esptool v.2.8
- I tried flashing with and without -fm=dio
- I diligently erased flash between each write
- I tried flashing with -b 115200

But since I can access micropython and initiate the wlan class, can it really be a flashing issue?

lalondesteve
Posts: 3
Joined: Thu Jun 11, 2020 4:53 pm

Re: OSError: scan failed

Post by lalondesteve » Mon Mar 29, 2021 4:04 am

I guess I'll answer myself for posterity and to prevent anyone else running in circle on the web like I did...
(https://xkcd.com/979/)

This applies to d1mini v3.0.0
The answer to those issues were faulty hardware. There was a missing layer on the bottom of the pcb. It can be easily identified by the two gold plated dot close to the chip on the bottom as per attached picture.

All you have left is contact the merchant and ask for refund/replacement.

Hope that helps!
Attachments
d1mini-good_or_bad-small.jpg
d1-min bad manufacturer
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