ESP8266 Community Forum

- Mon Jun 13, 2022 7:14 am #94761 Hello,

I have a WEMOS D1 Mini Pro with a WEMOS Power Shield mounted on top.
The Power shield is powered with 15V - which then powers the D1 mini Pro via the 5V pin.

The problem is the ESP8266 is permanently in reset.
I traced the problem to the CP2104. When the USB cable is plugged in, the CP2104 is powered and the RTS & DTR are both high, so the ESP8266 comes out of reset.

But when the board is powered via the power shield, the CP2104 is NOT powered. Only VDIO is at 3.3V. The RTS pin is low, which hold the ESP8266 in reset.
There is a diode between the USB VBUS signal and the 5V pin (D2). This diode prevents the CP2104 from being powered when the D1 mini Pro is powered from the 5V pin.
If I short this diode, CP2104 is powered even when the Power Shield is powering the D1 mini Pro and the ESP8266 comes out of reset.

Shorting out the diode seems to be a fix but I can't believe this is a standard fix and I'm the only one with the problem.
So has anyone else had WEMOS D1 Mini Pro powered via the 5V pin and stuck in reset?
What is a more elegant fix?
How do WEMOS expect it to work?

Ray

- Tue Jun 14, 2022 7:48 am #94769

Hello, is the diagram that you shared, the standard design of WEMOS shield? Or you customized it?

Standard diagram pulled from the web. Included just to show D2 that I shorted.
Ray