Constant random WDT on D1 Mini

[artran]

Hi,
I'm having some issues with MicroPython on several ESP8266 D1 Mini boards. I can flash them and get a REPL fine. I can put a program on them and it runs. The issue is that I'm getting reboots caused by the watchdog all the time. If I run without WiFi it might run for a couple of minutes before the watchdog fires but if I do stuff with the WiFi (even scanning for available networks) it dies within a few seconds.

I have three boards and they all show this behaviour although one is worse than the others. I've taken the worst board and reprogrammed it with an arduino sketch that constantly sends messages over WiFi to a HTTPS server to simulate a worst case example but it runs absolutely fine for many hours.

I've searched all over the forum and the net but nobody else is reporting similar problems. Am I missing something obvious?

Cheers,
Ray

[Roberthh]

That is hard to tell. I fired up a Wemos D1 Mini board here, and it runs pretty stable, while doing wlan scan all the time and being ping'ed at the same time. Even if it might look like a software problem, hardware related causes shoudl be considered, like short power drops.
- Try to change the USB cable and/or the USB port on your computer.
- If the EN pin is accessible, try to pull that up to 3.3V, and/or add a 100n capacitor between than pin and GND.
- Try to do the same with the RST pin, and/or add a 100n capacitor between than pin and GND.
The latter two bullets should not matter on a genuine Wemos D1 Mini. But clones may not have that.

[artran]

Thanks for the suggestions.

I have already tried several different USB cables and USB ports, all with the same behaviour. I should also mention that the setup I'm using is the same as I've been using with MicroPython on an ESP32 for months.

I'll try your ideas about the EN and RST pins - as you guessed I'm using a cheap clone rather than a genuine Wemos board. The biggest mystery to me is that the board behaves perfectly well when running Arduino style C++ code - in fact I've rewritten my project in C++ because it was a tiny program and I needed to ship it.

I'll add any findings to the thread as soon I can.

Cheers,
Ray

[Zolee]

That is hard to tell. I fired up a Wemos D1 Mini board here, and it runs pretty stable, while doing wlan scan all the time and being ping'ed at the same time. Even if it might look like a software problem, hardware related causes shoudl be considered, like short power drops.
- Try to change the USB cable and/or the USB port on your computer.
- If the EN pin is accessible, try to pull that up to 3.3V, and/or add a 100n capacitor between than pin and GND.
- Try to do the same with the RST pin, and/or add a 100n capacitor between than pin and GND.
The latter two bullets should not matter on a genuine Wemos D1 Mini. But clones may not have that.

Hi!
Where is the EN pin on Wemos d1 mini?

[Roberthh]

The EN pin is not accessible at the edge connectors. It is pulled up in the board to 3.3V.

[pythoncoder]

@artran I have done a lot of work with genuine WeMos D1 Minis and found them to be as good as the reference board. I'd suspect the quality of your clone boards.