I am building a small electronic project, and I am incorporating module nodeMcU 8266 in a box. I would like to know which pins are for "flash" and for "reset" I know there are 2 buttons on the module for those 2 actions, but I would like to add 2 external buttons for those function on the case of the project, like that I will not need to open the box everytime. I looked on the net, and I guess that for "reset", I must connect to pin "Rst" and pin "Grd", I mean those 2 pin must be shorted, but I prefere to get confirmation before to go further. And also for the "flash", what are both pins that I must connect the external push button to, to replicate the button present on the module itself.

Also I would like to connect an external LED to the module, following the state of the blue SMD led. The thing is that there is an SMD blue led on the module, I want to know what are the 2 pins that are similar to the contacts of the blue SMD led. I want the External LED that I plan to incorporate to the case of the project, to light up when the SMD blue led on the module is on, and when the led to be off when the blue SMD led is off. I want that both follow the same state. Blue SMD led "On" >>> external led "On" and Blue SMD led "Off" >>> external led "Off"

Sorry for the little confused explanation, and thanx in advance for any help and support.


The v0.9 and v1.0 NodeMCU boards have 2 LEDs: One on the AIthinker module, and one on the actual NodeMCU board.

The AIthinker module's LED is connected between Vcc (3.3V) and GPIO2 (labeled D4 on nodeMCU). It turns ON when D4 is set LOW.

The NodeMCU LED is connected between Vcc (3.3V) and GPIO16 (labeled D0 on nodeMCU). It turns ON when D0 is set LOW.

The pin labeled RST is the Reset signal from the AIthinker module, and is active-high, meaning you connect RST to GND to put the device in a reset state.

The pushutton labeled FLASH is connected between GND and GPIO0 (labeled D3 on nodeMCU). When the this pin is LOW when the ESP8266 comes out of a reset state, the chip is in flash-bootloader mode, meaning it is ready to receive a new sketch. On a NodeMCU, however, the ESP8266 chip is placed in flash mode by the USB chip and the flashing software, so there is not a need to manually press this button.

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  • Thank for the reply and the great information. I think I have the NodeMCU board, on its back side it is righted "NODEMCU Amica" unfortunatly I could not get any info on the version. so for the additional Reset switch I follow your instruction, and the point is resoved. About the additional Flash button, I think I will go without it, as you instructred. – ZipZwan Mar 21 '19 at 19:47
  • About the additional external LED,so I followed your instruction and added a LED between PIN D0 and GND. It is ON when the blue Led on the Board is off, and turns off when the Board's Led light up. so or external LED or included LED board is on. Me I am looking that they follow the same state, Included LED ON >>> external LED ON I fund some line the the sketch that I am supposed to flash to the board, maybe iit has something to do with it. maybe somebody can take a look. void setup() { #ifdef USE_LED16 pinMode(16, OUTPUT); digitalWrite(16, LOW); #endif – ZipZwan Mar 21 '19 at 19:47
  • To swap the on/off for your external LED: If the legs are between GND and IOPIN, then reverse LED (anode - cathode) and connect between VCC and IOPIN. – jose can u c Mar 21 '19 at 20:03
  • I do not find PIn IOPIN, I looked on the board, and also tryed the different picture I could find, like from this site: circuit-diagramz.com/… I see there are different GPI, maybe you meant GPIO0, so writed Pin D1 on the Board itself? – ZipZwan Mar 21 '19 at 20:12
  • I mean whatever I/O Pin you are controlling it with – jose can u c Mar 21 '19 at 20:13

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