I'm trying to power on my NodeMCU ESP8266 Ver 0.1 (thats what is written in board), via VIN and Ground with my phone charger.

I'm 100% sure that the USB charger is working, providing 5V, and that the ground and VIN are connected to the right positions.

If I use the same phone charger via the NodeMCU USB, the program blinks the builtin led alright.

If I power via VIN, it flashes when I connect the charger to DC, but the program does not work. It seems as the NodeMCU is not powering on complety.

Bizarrely, if I short 3V and G pins, the board starts working normally as powered directly via USB port.

This is the code

 ESP8266 Blink by Simon Peter
 Blink the blue LED on the ESP-01 module
 This example code is in the public domain
 The blue LED on the ESP-01 module is connected to GPIO1 
 (which is also the TXD pin; so we cannot use Serial.print() at the same time)
 Note that this sketch uses LED_BUILTIN to find the pin with the internal LED

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);     // Initialize the LED_BUILTIN pin as an output

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, LOW);   // Turn the LED on (Note that LOW is the voltage level
                                    // but actually the LED is on; this is because 
                                    // it is acive low on the ESP-01)
  delay(1000);                      // Wait for a second
  digitalWrite(LED_BUILTIN, HIGH);  // Turn the LED off by making the voltage HIGH
  delay(2000);                      // Wait for two seconds (to demonstrate the active low LED)

This is the wiring

Just as a follow up: I've never solved the problem in this specific board, so I ended up buying a newer one which works fine.

  • what is the expected voltage range ar Vin?
    – jsotola
    Commented Nov 24, 2020 at 5:02
  • As I know, 5 to 12 V
    – Gabriel G.
    Commented Nov 24, 2020 at 5:10
  • Can you check the voltage across AMS 1117 when you connect supply voltage to the esp-01 board
    – Maaz Sk
    Commented Nov 24, 2020 at 7:53
  • Input vs Ground is 3.4-3.6V when connected via VIN. Output vs Ground is 2.5-2.8V when connected via VIN. Input vs Ground is ~4.7V when connected via USB port; Output vs Ground is ~3.3V when connected via USB port. Using the exactly same brick to test both
    – Gabriel G.
    Commented Nov 25, 2020 at 15:00

2 Answers 2


I faced the same issue. My problem was on this version of board both ground (G) pins on the side of Vin pin (I say left side of the board when usb is towards bottom direction) do not have connection with the ground of the 3.3v regulator or to the Gnd pin on right side of the board !! No continuity from ground pin to regulator is the problem I understood. The moment I connected 5v between Vin and Right side 'G' pin it started working. Check and try if not resolved yet.

  • I can confirm the Cherry's experience. The G pins on the left side are not connected with the regulator. Commented Aug 6, 2022 at 9:45

Interesting problem. The input range for Vin is 5.5 to 10 volts. This link will give you more information: https://www.make-it.ca/nodemcu-arduino/nodemcu-details-specifications/ I would not venture to guess that your board is OK, since you short pins all kinds of nasties can happen. Also you do not state your reference point for your voltage measurements so I assume it is ground but the readings do not appear correct. How are you 100% sure that the USB charger is working, providing 5V, and that the ground and VIN are connected to the right positions. Did you measure it with the load connected? Can the charger output the voltage at the current you require?

  • I can measure the breadboard powerrails, and they show 5V. I have two boards of the same vendor, both present the same problem (one I haven't shorted at all). I'm 100% sure because I tested load (via SK6812 leds and I can power an arduino too). This charger can output 5, 9 or 12V. 5V is max 3A, I can power a little more than 1 meter of RGBW led strips. This specific board is requiring 5V from the charger. Also, from the link you showed me, the voltage is 4.5V to 10V
    – Gabriel G.
    Commented Nov 27, 2020 at 1:06
  • Check the ground pin on the ESP and see if it is less then 0,02, if not you have an open or not connected ground connection.
    – Gil
    Commented Nov 28, 2020 at 5:06

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