When i Connected Rx>Rx (Rx Of module To Pin 0 Of Arduino) And Tx>Tx ( Tx Of Module To Pin 1 Of Arduino), The AT Command Test shows The Following error With Scrambled Words, but when I Connect Rx>Tx (Rx Of Module To Pin 1 Of Arduino) And Tx>Rx(Tx Of Module To Pin 0 Of The arduino), The AT Command Test Shows a Blank Screen. I Connected VCC, CHPD and RST Of Module to 3v Of Arduino and GND Of Module To GND Of Arduino. So How Do I Connect Arduino To Wifi Module which passes the at command test, Btw i Have an Intermediate, ie Motor Shield, I Connected Motor Sheild To Arduino And Then I connected Wifi Module To Motor Shield. Listen So I need To Connect Wifi Module To Arduino, such that there isnt any error. what do i do?RX>Rx and Tx>Tx Pair

  • You cannot connect an Arduino's digial pins 1 and 0 to both an ESP8266 and the serial USB, unless you disable their use by the ATmega, for example hold it in reset if you are just trying to borrow the Arduino's USB serial. Oct 13, 2016 at 23:03
  • many ESP8266's operate at 74880baud by default - this is 115200 * 26 / 40 ... because most ESP's use a 26Mhz crystal as opposed to a 40Mhz one Oct 14, 2016 at 1:10
  • @ChrisStratton - unless the unposted code doesn't open the serial port as discussed here
    – Nick Gammon
    Oct 14, 2016 at 2:47
  • Sounds like a baud rate issue as others have mentioned. Posting code would make things clearer. Please read How do I ask a good question?.
    – Nick Gammon
    Oct 14, 2016 at 2:48
  • You have three hardware serial devices: the ATmega's pins 0 and 1, the ESP8266, and the USB serial converter to which the serial monitor is linked. You can only connect two of these, not all three. If you want to connect the serial monitor directly to the ESP8266, you have to disconnect the ATmega pins 0 and 1, either electrically or by making sure they are not activated for serial. If you want to insert the ATmega and its program between the serial monitor and the ESP8266, then you have to move the ESP8266 connections to some other ATmega pins and use a software serial instance on them. Oct 16, 2016 at 19:10

1 Answer 1


The first connection you made between arduino and esp which resulted in some random data means both are communicating whereas the second connection where the screen shows blank means communication hasnt been established on account of incorrect wiring. So your first connection tx>tx and rx>rx is correct.

The only two area which you need to check is the baud rate and the mode of return. Some Esps work at 115200 with mode carriage return. So you can try different combinations of baud rate and mode to check which one does your Esp support.

  • "Random data" normally means the baud rate is to high. No data means its to low (or 'broken' in some other way) Oct 14, 2016 at 8:05
  • @Matt you might be right but in this case the results are observed when wiring is interchanged. Your point would have been valid when the connection is correct and the above mentioned observation would have been observed on changing baud rate. Here the connection itself is an issue.
    – Rohits112
    Oct 14, 2016 at 14:20

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