I want to make a very simple webserver who sends welcome message to anyone who joins it using WiFi.

I have a ESP8266MOD module, I want to program it using arduino ide and arduino uno board. How I can use arduino uno to program this WiFi module without using urat USB serial board?

SoftwareSerial.h is not working with esp.write() command, I believe it is because of low power, can anyone suggest me on power supply too?

Thanks in advance,


  • 4
    Why use a mini to tell a Ferrari what to do? Program the esp8266 directly and screw the Arduino.
    – Majenko
    Commented May 13, 2017 at 21:26
  • just short the UNO's reset to ground to use it as an "FTDI" to program the ESP from the Arduino IDE
    – dandavis
    Commented May 13, 2017 at 21:26
  • Hi dandavis, can you please show me an example, because how to use UNO as FTDI is not documented well anywhere...
    – AppMonk
    Commented May 15, 2017 at 14:19
  • your absolutely right Majenko, but my problem is that I don't have URAT or FTDI, so to connect to IDE I have to use UNO itself as FTDI
    – AppMonk
    Commented May 15, 2017 at 14:26
  • rx>tx,tx>Rx,gnd<gnd, on avr: rst to gnd. then you can use at mode et al
    – dandavis
    Commented May 15, 2017 at 21:08

1 Answer 1


When you use the Uno for its UART only, i.e. grounding RST pin, its Rx pin 0 becomes Tx, and Tx pin 1 becomes Rx -- because that's what pins on the UART you are connecting to. AppMonk didn't say what specific breakout/ chip mount he's using, there are many, or say how he's managing level-shifting from the Uno to the ESP if needed. The Tx pin on Uno (0, labeled Rx) is putting out 5v and the ESP would prefer 3.3, so level shifting w/ simple voltage divider is recommended. You don't need to level shift the Tx signal from ESP to Arduino's Rx (pin 1).

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