Wemos D1 Booting Problem

Other Hardware 3rd Party Boards
1

I’ve been really struggling with a WEMOS D1 Mini. When I power it with regulated 5v it doesn’t boot until you press reset.

I’ve pulled up every GPIO+RST except GPIO15 which is directly grounded.

When I power it up and test voltage, GPIO0 shows 1.6v (presumably low?!) whereas GPIO2 (next to it) shows 3.3v. These are pulled up using 4k7 resistors off the 5v line. I tried off the 3.3v previously, same result.

Here are a couple of photos - this is my second attempt to get this board working, and I’ve tried many, many suggestions I’ve read online.

You will see 2 regulators and a big cap next to one of them - these 2 parts are not currently used. I intended this to provide a separate 5v to power the LCD, just in case it was a power issue.

I do have caps on the 5v and 3.3v lines.

I’ve tried two different Wemos D1 Pro boards. I’ve also painstakingly recreated the circuit twice with the same results.

I was previously using an ESPDuino with a screw shield, and near identical circuitry - that one always boots despite identical connections to the same pins.

Very stuck!! Any help would be much appreciated.

IMG_3295.JPG

IMG_3296.JPG

2

GPIO0 should be 3.3V. Check your connections and solder joints, maybe it's shorted to ground somewhere.
You shouldn't add any external pull-up or pull-down resistors, everything you need to run the ESP8266 are on the board. Shorting GPIO15 directly to ground is a very bad idea.
Pulling the pins of a 3.3V device up to 5V doesn't make much sense either.

Pieter

3

Thanks - i've tried that, by rebuilding it twice.

I've just done a test where the only connections are 5v,GND and the two I2C pins. Still doesn't boot until you press the reset button.

There are two posts i came across whilst googling, much the same problem, but inconclusive results:

https://forum.wemos.cc/topic/65/problems-booting-with-5v-pin-power-supply