Wemos D1-Mini USB connection issues

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Wemos D1-Mini USB connection issues

#1 Post by SpasT » 12 May 2020, 08:56

I bought few Wemos D1-Mini boards and all of them have connection to USB problems.
Found some posts over the internet, but no real solution. When I look in datasheet of CH340 I see that at pin16 of chip is VCC (5v from USB), but on the board this pin is connected to 3,3V. The simplest modification is to rise this pin from the board and connect it to USB VCC pin.
Now the connection is stable and no more disconnections.
I hope this can be usefull for others with the same issues.

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Re: Wemos D1-Mini USB connection issues

#2 Post by ThomasB » 12 May 2020, 22:58

Interesting solution. Your 5V conversion should also change the V3 pin, per the data sheet.

Why? The CH340 chip supports 3.3V VCC if the "V3" pin is also connected to 3.3V. When using 5V VCC, the V3 pin must be only connected to a .1uF cap (V3 is not connected to VCC).

ch340-1.jpg (67.75 KiB) Viewed 605 times
ch340-2.jpg (102.08 KiB) Viewed 605 times

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Re: Wemos D1-Mini USB connection issues

#3 Post by TD-er » 13 May 2020, 09:45

That's good info.
Maybe you could add this also to the Wiki, as I guess a lot more people will run into this.

Sounds like a new batch of so called Wemos D1-mini units has been sold to a number of AliExpress sellers so we will hear a lot more about these issues the upcoming weeks/months.

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Re: Wemos D1-Mini USB connection issues

#4 Post by grovkillen » 13 May 2020, 09:59

I added a link to this thread to the list of ESP "hardware": https://www.letscontrolit.com/wiki/inde ... P_hardware

I'm sorry for not being fast on the documentation, the GUI has been taking it's time + I have tried to get myself some income. It will be changing soon I hope.
ESP Easy Flasher [flash tool and wifi setup at flash time]
ESP Easy Webdumper [easy screendumping of your units]
ESP Easy Netscan [find units]
Official shop: https://firstbyte.shop/
Sponsor ESP Easy, we need you :idea: :idea: :idea:

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