NodeMCU ESP8266 Ver 0.1 not powering on with VIN 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)
}
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?