I have early midnight accident of my Lolin/Wemos boards. I tried uploads my sketch with a assembly VIN to GND as my reset button, when i uploads my sketch at more one hundred times, i get my boards cannot be online again or my port cannot readable to my Ubuntu as /dev/ttyXXX. usually when i plugged the Usb3.0 cable, the blink led should be turn on at my boards but i didn't get it. How i can re-flash my boards to be online again?

Thanks in advance.

  • Am I understanding right, that you shorted Vin to Ground? Have you tried another USB port? Maybe you have blown it's driver.
    – chrisl
    Commented Oct 25, 2018 at 10:58
  • @chrisl yap it just as reset button, i tried too but i didn't get my port again, perhaps my driver have blown but when i bought it ,i didn't need to installed the drivers. Commented Oct 25, 2018 at 11:03
  • @chrisl do i need a esp8266 firmware flasher to get it back? Commented Oct 25, 2018 at 11:09
  • the port has nothing to do with the esp8266. USB is handled by the USB converter chip. You used short circuit as reset?
    – Juraj
    Commented Oct 25, 2018 at 11:22
  • I meant the electronic parts inside the USB port of your PC. Sorry for being unaccurate. So you can try another USB port or another PC. Also look at the board, if you can find any parts that look damaged. Currently I cannot investigate further
    – chrisl
    Commented Oct 25, 2018 at 11:26

3 Answers 3


Shorting VIN to GND will over-stress the diode that is in-line with the power coming in from the USB.

The result

  • The diode will blow and you will not get power from the USB to power the board.
  • The PC may detect "over-current" and shut down the USB port
  • The USB port on the computer may be damaged

How do you fix it?

  • Replace the diode if blown.
  • Use a different USB port.

How do you work around it?

  • Provide an external 5V power source to VIN & GND if the diode is blown

How do you avoid it happening in future?

  • NEVER short VIN to GND, even for a short time. There is a reset pin RST provided for the purpose of resetting the board.
  • i found it forum.arduino.cc/index.php?topic=504901.msg3446033#msg3446033 ,do i took another boards and connect 3.3v output to my esp? Commented Oct 25, 2018 at 12:46
  • That's a different issue. Get a USB phone charger, butcher a USB cable, and connect the red wire to VIN and the black wire to GND. It may work.
    – Majenko
    Commented Oct 25, 2018 at 12:48
  • okay i trying, do i plug usb3.0 port to esp connector too? Commented Oct 25, 2018 at 12:52
  • You will need to for it to communicate with the computer.
    – Majenko
    Commented Oct 25, 2018 at 12:53
  • 1
    Then throw it away and get another. They're cheap enough. And don't do it again.
    – Majenko
    Commented Oct 27, 2018 at 9:40

If the device still blinks and boots and whatnot, but doesn't connect to the computer, you've probably only broken the USB part of the NodeMCU.

Use the USB-TTL of another MCU. If you have an Uno, it's RST>GND, GND>GND, TX-RX, RX-TX. Mind GPIO 0+15 for programming. You can also use a USB TTL adapter, aka "an FTDI", the kind they used to use before everything had cheap built-in USB chips.

  • my device not blinks and cannot detect my port, do i Majenko advice? Commented Oct 25, 2018 at 16:11
  • well my suggestion is low-effort and free to try. If I was looking at replacing parts on a NodeMCU, i would just get a new NodeMCU, they are only a few dollars, and fixing it could take hours. If you find the ESP half still working, there's a lot of projects you can still use the board for, especially if you enable OTA updates...
    – dandavis
    Commented Oct 25, 2018 at 16:13
  • i try to understanding my issue without a few dollars, and to get work around it, thanks Commented Oct 25, 2018 at 16:18
  • how i can enable OTA updates for esp8266? Commented Oct 25, 2018 at 16:25
  • this is the simplest method, since it's just an include and one extra line of code on top of an existing server config: github.com/esp8266/Arduino/blob/master/libraries/… There's a few other ways to do it as well, through the ardunio IDE and through an external HTTP server, but this one is simple.
    – dandavis
    Commented Oct 25, 2018 at 16:29

Thanks to @Majenko my pal, from him advice i get a alternative ideas for fixed my issue.

What i tried :

  1. I found this and I took my Uno, i pined 5v (Uno) to 5v (Esp) and i declared 13 pinout as the led blinky and then i uploaded "BlinkyWithoutDelay" sketch, it's seems doesn't work.
  2. I pined 5v (Uno) to 5v (Esp), Gnd (Uno) to Gnd (Esp) and i declared 13 pinout (Uno) to D3 pinout (Esp) and then i uploaded "BlinkyWithoutDelay" sketch, it's seems doesn't work.
  3. I tried from Majenko advice to provide a Usb phone charger and connected white wire to 5v (Esp) and black wire to Gnd (Esp) without Uno board, and then i uploaded "BlinkyWithoutDelay" sketch, it's seems doesn't work.
  4. From the 2nd point and the 3rd point, i run 2nd point without declared D3 pinout as the led blinky, and i changed from 5v to 3v3 (Uno and Esp), and after uploaded the sketch, it's seems the dim light (Esp) works like dim light (Uno) but i still cannot get my port for my esp, i had idea to unplugged my Uno and i changed from 5v to 3v3 and i uploaded my sketch, it's seems works to me. but i still cannot 5v properly or really death.

The Solution

From the 4th points , the solution is i provide a external power to 3v3 (esp) and i plugged to Usb2.0, i also plugged Usb3.0 as serial communication. when i uploaded "BlinkyWithoutDelay" sketch, it's seems works. The conclusion is my 5v pinout really death cause the diode for 5v pinout is blown up therefore i changed to 3v3 pinout.

See my damaged board below


That's also solved another my Esp boards. hope anyone didn't make a shorted between 5v to Gnd like me.


  • this should be an answer?
    – Juraj
    Commented Oct 29, 2018 at 16:19
  • @Juraj that's solved my issue, i get my port again, why you provide me down vote man? Commented Oct 30, 2018 at 8:43
  • this is not how an answer should be written and I don't understand the solution.
    – Juraj
    Commented Oct 30, 2018 at 8:49
  • @Juraj perhaps my bad English man, I editing!! Commented Oct 30, 2018 at 8:54
  • leave out the dead ends. write down the working wiring
    – Juraj
    Commented Oct 30, 2018 at 8:55

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