Clone Wemos D1 mini boards intermittent resetting and other problems

I’ve recently been experimenting with the ESP8266 modules and made a YouTube statistics counter as the first and experimental project. I used a NodeMCU for that which gave me no problems at all. However there is a smaller board, the Wemos D1 mini which on first impressions looks like a more ideal board for final projects and can easily be soldered to veroboard and prototyping boards.

The problem I had was my boards were clones as the originals no longer seem to be made and sellers advertising genuine boards (even showing a photo of the genuine board) are sending clone boards instead. Now that may not seem like a bad thing but I had constant intermittent reboot problems and the board would stick on the bootloader in flash mode if the 5V supply rail was ever so slightly above 5V. That meant it would boot connected to some devices that provide USB power and not boot on others.

This was driving me nuts and I wasted a lot of time trying to find the problem thinking my code was at fault believing the intermittent reboot was due to a stack overflow. I came across this reddit post which shows that mostly these clones come with voltage regulators that cannot handle the load the ESP8266 puts on them. Uh oh.

This post is dated 2018 and a quick look at my boards, from different sellers had voltage regulators marked 4A20 which indicates it can supply a maximum current of 150mA. However the ESP8266 draws a peak current of 430mA especially at boot.

So I replaced that regulator with a more capable AMS1117-3.3 which fixed that problem. However it didn’t fix the won’t post if 5V supply is just over 5V; my PS4 outputs nearly 5.2V. A bit high maybe but within the USB specification of 4.75-5.25V. One small caveat of the AMS1117 is that it has a high quiescent current which makes it unsuitable for battery powered projects. Another alternative is to simply replace the low spec regulators with the same ones used on the genuine boards; an ME6211.

Ultimately it resulted in a fail with the end result being stuck with a useless board that could not be used. These boards are still being sold and will not work nor can ever work properly due to inadequate components fitted instead of the components fitted to the original Wemos spec.

It makes me wonder why even 2 years later these are still being sold. But with them being so cheap many will never get returned as inexperienced hobbyists may well give up on them believing their code or their circuit is at fault.

In the end I just binned them. But I made a YouTube video about the issue which you can watch below.


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