I am trying to connect an ESP8266 to my Arduino Uno.

enter image description here


RX -> RX
TX -> TX
CH_PD -> 3.3v (Arduino 5v using voltage regulator)
VCC -> 3.3v 

I am running the RX and TX pins through a logic converter, dropping those down to 3.3v. Also, I have read that normally RX goes to TX and vice versa, but since I am trying to communicate with the chip using my computer (not the arduino) it needs to be the other way around.

I can't get the AT command to work on any baud rate. I was paying attention mostly to 9600, 115200, and 57600...I checked some others but it seemed like from reading these are the most common.

I used a multimeter to check the voltage of the RX/TX pins and after the logic converter my meter says it is outputting 3.2 volts (is this two low for serial to work?) Is their some +/- in the reading and it is actually 3.3v?

enter image description here

How do I go about troubleshooting this? Is it possible the AT firmware isn't loaded onto my chip? (I purchased it new, and recently).


I'm reading about my logic level converter here, and I'm wondering if I have it setup right. My converter is labeled with HV -> HV4 and LV -> LV4 (you can see in the below picture). I'm wondering about where it says:

The middle section of the board is where the reference supply for your high and low voltages should go. Supplying voltage to all four of these pins is required. If you’re converting 3.3V to 5V (and vice-versa), for example, you’d run 5V into the “HV” side, and 3.3V into the “LV” input. Make sure each is grounded too!

So I need to provide power ("reference" power)? Some diagrams I have seen do this but I wasn't sure why:

enter image description here


I provided the reference supply and it up'd my voltage reading from 3.2 to 3.27 (I can assume it has enough voltage now?). I still can't connect with AT - on one of the baud rates I was getting stuff like !? as output.


I changed what pins were being used by RX/TX on my logic level converter, and now when I type AT on baud 115200, it outputs AT. Below is what it looks like for this configuration:

enter image description here

Do the soldered connections look good on the logic level converter?

2 Answers 2


Try loading the ESP8266-01/12F firmware once more from the Espressif and see if it's working correctly. Hope you know how to change to firmware/programing mode?

(GPIO 0->ground)->rest->burn program->GPIO0->high->power reset)


After writing such a long question, hopefully this is useful to someone else: After changing the logic converter channels (not sure why the first two weren't working) I was receiving AT as output - the only thing I needed to do after that was change No line ending to Both NL & CR and I am receiving AT OK now.

  • 2
    Please, accept your own answer to close this question.
    – user31481
    Nov 18, 2017 at 6:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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