ESP8266 Community Forum

- Wed Oct 26, 2016 9:30 pm #57191 I have this older wemos D1 (UNO size) board running the WiFiScan example sketch. However, most of the time it cannot find ANY networks although I know they're around for sure... Then again, sometime when powered up it just runs and reports at least 10 of the closest networks with all their correct parameters as described in WiFiScan example sketch.

The only way to make it working is to try patiently to power it up and down multiple number of times. Sometime it works immediately after power-up, but when it doesn't (and that happens most of the time say 90%) it never recovers from that dead state and keeps continuously reporting the following:

scan start
scan done
no networks found

Power supply's not a problem as I tried both USB and external and they are both rock solid. Then again - it seems to work but very very sporadically, and only when it starts correctly after the initial power up. It looks almost like some kind of latch-up scenario. When it starts correctly it keeps running until the next power-down where it might or might not resume network scan again.

What might be the problem?

- Fri Oct 28, 2016 2:07 pm #57298 Just a guess. According to Espressif when the ESP8266 powers up it does an analog test and measurement for the RF section. Maybe this is too much of a load for the regulator that is supplying the +3.3 volts.

They say the logic could need 200mA and the RF/analog portion 500mA. That is a lot of current. A lot of people have been saying that the current requirements of the ESP8266 is 200mA. Maybe a longer term average but the peak currents at different times is what causes problems.

If you are having that much of a problem, do the smart thing and throw the board in the garbage. It is not worth the aggravation.

- Fri Oct 28, 2016 4:35 pm #57310 I've ordered a couple of "bare" ESP-12 modules and will try to repeat my test with the new ones. Just curious what can I eventually find out and which part to throw away to garbage