I'm trying to make my ESP8266-01 work with a simple FTDI board, wired like this schematic:

ESP8266-01 Wiring diagram for reflash mode

From here.

Everything works nicely when in "Flash mode" (even with ESP8266 NodeMCU Flasher or doing everything within Arduino IDE). But when I disconnect GPIO 0 from ground pin from FTDI, everything seems to freeze. Symptoms:

  • FTDI LEDs are all lit (both green LEDs and red LED).
  • ESP red LED is barely lit, almost completely turned off.
  • Nothing is recognized in my computer.


  • I've tried plugging GPIO 0 into VCC. Nothing works too.
  • I'm powering the entire setup with USB current only.

What am I doing wrong? Could this problem be solved only with external power supply? If yes, how much current does the ESP8266 require?


2 Answers 2


You are trying to power the ESP8266 from the on-board regulator of the USB-serial converter, who is not able to supply the current required to actually run the ESP8266 WiFi. (You might be able to run an application on the ESP8266 that doen't enable the Wifi).

Use a 3.3V supply than can provide at least 400 mA.

  • \$\begingroup\$ Thank you for your answer! When playing with an external PSU, how do you wire ESP8266-01, FTDI and PSU? I ask this, because USB already provides +5v that is downconverted to +3.3v for ESP8266-01 (diagram above). I know that I must connect both ground pins (FTDI and PSU to achieve common ground reference), but where should I connect the +3.3v from PSU? \$\endgroup\$ Commented Sep 9, 2016 at 21:51
  • \$\begingroup\$ After some research, I've found here, that I need to plug +3.3v from ESP8266-01 into +3.3v of external PSU, and wire all ground pins (FTDI, ESP and PSU) together. Anyway, thank you again for your answer. \$\endgroup\$ Commented Sep 10, 2016 at 4:24

I also faced the same issue when i was using ESP8266. For that, i used 3.3 V linear voltage regulator which i connected to 9V/1A Power Adaptor, to get ample amount of current.

  • 1
    \$\begingroup\$ Please also include a circuit diagram and answer the users questions. Thanks \$\endgroup\$
    – Voltage Spike
    Commented Sep 9, 2016 at 18:44

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