I have a unidirectional communication from NodeMCU (ESP8266) -> Arduino UNO. The communication works when I power both the devices to my computer. Note that since it is from NodeMCU to Arduino only, I don't use a voltage regulator. However, when I use a battery supply 9V and connect to DC jack or 9V battery, the serial communication doesn't work. I tried even with the voltage regulator.

It is mentioned that I use something between 9V-12V in the spec. Is it not working because 3.3V/5v from NodeMCU is not sufficient? How do I fix this problem?

  1. Currently for the voltage regulator "high", I am supplying 5V from Arduino. Should I provide another supply to pass 9v?

  2. Does it power on if I provide 5V to DC jack or Vin?

  • Please rephrase you question into something understanteble – Dat Ha Oct 21 '16 at 19:07

9V "transistor" (PP3) batteries are very weak. They barely provide enough current to power the Arduino, let alone a power hungry device like an ESP8266.

You're basically trying to tow a caravan with a skateboard.

| improve this answer | |
  • What should I use? 9V is sufficient to power arduino for a simple blink program – Nikhil Oct 22 '16 at 3:33
  • AA batteries or Lithium ion. – Majenko Oct 22 '16 at 7:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.