ESP8266 /ESP 32 AT commands not working?

Projects Programming
1

Initially my ESP8266 AT commands worked , but after programmed some simple led blink code , its not working
similarly for ESP 32 also

What should i do?

2

Just a wild guess, but you've overwritten the code in the 8266/32 that handled AT commands with your simple led blink code.

1 Like
3

It is nothing surprised in it - the mcu can only contains a single code. If you uploaded your sketch in it, it replace AT-command firmware.

4

I am looking for sensor data want to send from esp 8266 to the another esp 8266 using AT commands

Now that overwriting issue will create problem for me?

5

Since the code that handles the AT commands has apparently been erased and overwritten, I'm going to go with yes, it's already created a problem for you.

I'd imagine there's some process to get the original firmware reloaded, but as I've never had the need to, I have no idea how or even if it can be done.

6

Why?

That would require another microcontroller to send the AT commands to the transmitting ESP and yet another microcontroller to receive the data from the receiving ESP. That's 4 microcontrollers where only 2 are needed.

7

if you have overwritten the AT code why not use the ESP WifI libraries or ESP-NOW?
do you have local WiFi?
what is the distance between nodes?

8

There is an instruction on Github on how to re-upload / update AT-commands firmware.

That said, i found the whole AT-commands process and programming clumsy, but the explanation is available, and you already have the hardware connections to do so, which are the same as for uploading the blink sketch.

9

Yes , i have two ESp 8266

10

with in a room i am targeting(10-20m) , but i have to use AT commands only , because other device which have sample code with AT commands if change that even more difficult for me

So initially i want to test with AT commands between two esp. 8266 (then i will implement as what i need)

11

Thanks i will go through it and i will try on my device

12

It looks like your ESP8266 and ESP32 stopped responding to AT commands after uploading a simple LED blink code. This happens because flashing a new sketch overwrites the factory firmware, including the AT command firmware.

How to Fix It?

1. Reflash the AT Firmware

Since uploading code via Arduino IDE erases the AT firmware, you need to reflash it:

  • Download the correct ESP8266 AT firmware or ESP32 AT firmware from Espressif’s official site.
  • Use ESP Flash Download Tool (for Windows) or esptool.py (for macOS/Linux) to reflash the AT firmware.
  • Make sure you select the correct baud rate (usually 115200).

2. Check UART Communication

  • If you’re using an external USB-to-Serial adapter, ensure the TX/RX connections are correct.
  • Try different baud rates in the serial monitor (9600, 115200, 74880).

3. Set the Board to AT Mode Manually

  • For ESP8266: Hold GPIO0 LOW and reset the board.
  • For ESP32: Ensure IO0 is HIGH and EN is pulled HIGH before resetting.

4. Flashing Alternative Firmware (Optional)

If you want to restore full AT functionality, you can try flashing NodeMCU firmware or Tasmota instead of the default AT firmware.

For a step-by-step guide on reflashing ESP8266/ESP32 AT firmware, check out Giga Electronic.

Let me know if you need more details!

13

Then what you want is not possible. An ESP cannot run your sketch and respond to AT commands, it is one or the other.

14

No, it is a completely wrong.
As mentioned above, ESP8266 can't run a user sketch and respond to AT commands at the same code. So, you can't to work with AT-commands on the both ESP8266. If you need to use an AT-commands on the first ESP, you MUST NOT to use AT-firmware on the second board.

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