ESP32c3 mini - URC messages

LucioS
Posts: 4
Joined: Mon Sep 08, 2025 7:23 am

ESP32c3 mini - URC messages

Postby LucioS » Fri Nov 28, 2025 10:22 am

Good morning,
i have a question about the urc messages scenarios :

I send a AT command :
1 - the URC can be received before the answer ?
2 - the URC can be received in the middle of the answer?
3 - the receiving is random?

I'm receving datas (for examples from a server):
+IPD:xxxxxxxx

A urc can be received in the middle? like this : +IPD,0,n:xxxxxxxxxxxxxxxxxxx+CONNECT,0xxxxxxxx or a MQTT notify

In other words , is there a "syncronization" with the ongoing trasmissions from the ESP to the microcontroller?

Thank you.

Best regards,
Lucio.

esp-at
Espressif staff
Espressif staff
Posts: 335
Joined: Mon May 09, 2022 3:00 am

Re: ESP32c3 mini - URC messages

Postby esp-at » Wed Dec 17, 2025 6:48 am

@LucioS URC messages are asynchronous and are generated by internal events (Wi-Fi, TCP/IP, MQTT, etc.).
They are not synchronized with AT command execution, so a URC may arrive before, during, or after the response of an AT command.

However, the firmware ensures that:
  • Each message (AT response or URC) is output as a complete line
  • Messages are not byte-interleaved
So while messages may be interleaved at the line level, they are not mixed at the character level.

So a situation like this will NOT happen:

Code: Select all

+IPD,0,n:xxxxxxxxxxxx+CONNECT,0xxxxxxxx

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