ESP8266 Echos AT but will not Respond with OK

(click here to see index of all ESP8266 posts)

I’ve been playing with the ESP8266 a little for the past week and will shortly start posting some stuff, but the first head scratcher I ran across which I still have not seen documentation on is this:

You get the ESP8266 connected to your PC via an FTDI cable. When you type AT, it properly echos ‘AT’ back at you. But when you press ENTER (<CR>) you do not get an OK response.

Unlike anything else I’ve used in the past that uses the AT command set, control-M a.k.a. ENTER a.k.a carriage return (<CR>) is not enough. You must then press control-j (line feed).

So if you type AT<control-m><control-j> you should get an OK. At least I did.

In my terminal emulator of choice (an ancient copy of WRQ’s Reflections), there is a mode called AUTO LF. If I turn that on, then any time I press control-m, the sequence <control-m><control-j> is sent, and that solves the problem for me.


I took a look at PUTTY, the only other serial port terminal emulator I ever use and while it has an option that seems that it would do an auto lf, it does not work for me.


So with PUTTY, I still have to type control-m control-j to terminate each AT command.



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5 Responses to ESP8266 Echos AT but will not Respond with OK

  1. Pingback: Basic ESP8266 Setup and Operation | Big Dan the Blogging Man

  2. Richard says:

    You found the trick too! Took me over a week to figure it out. I was complaining to the seller that his product would not respond to AT commands 😦

  3. Fabio says:

    Thanks a lot, you saved me hours…!!!!! Damned CTRL-J!!!!!
    I’m using gtkTerm from Kubuntu, but the option CR+LF AUTO doesn’t work.
    It wants CTRL-J…..

  4. Grzegorz says:

    Implicit LF refers to incoming characters. It works correctly, it’s just not the setting you are looking for. The one you look for doesn’t exist though. It must be added by source code modification and recompilation od PuTTY. I did it and you can download modified PuTTY from my website. You can choose if Enter sends CR or CRLF sequence.

  5. Eddie says:

    Two days burning my brain with that, and you’re the only one that solved my problem. I don’t even know you but I already love you!
    Thanks, man!

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