Connecting ESP32-S3 Native USB to Quectel EG800Q Modem (USB Interface)
Posted: Mon Nov 10, 2025 6:56 am
Hi everyone,
I’m trying to connect my ESP32-S3 (native USB host) directly to a Quectel EG800Q modem through USB, to send and receive AT commands.
What I tried
Using UART, the modem works perfectly — I can send AT commands and get replies.
When I connect through USB, I get some USB descriptor data, so the hardware connection seems okay.
But I don’t get any readable AT response — it looks like the modem is in diagnostic (DM) mode.
Setup
ESP32-S3 with native USB host
Quectel EG800Q modem
Tried in Arduino IDE → didn’t work
Switched to ESP-IDF, as it supports USB host better
What I need
Any working example of ESP32-S3 communicating with a USB modem (CDC/ACM).
How to select and open the AT port (modems usually have multiple ports: DM, NMEA, AT, and data).
Has anyone successfully sent AT commands via USB (not UART) to a Quectel modem?
Any tips, code samples, or guidance would be really helpful.
Thanks!
Note: I am new to IDF , so please explain in simple ways
I’m trying to connect my ESP32-S3 (native USB host) directly to a Quectel EG800Q modem through USB, to send and receive AT commands.
What I tried
Using UART, the modem works perfectly — I can send AT commands and get replies.
When I connect through USB, I get some USB descriptor data, so the hardware connection seems okay.
But I don’t get any readable AT response — it looks like the modem is in diagnostic (DM) mode.
Setup
ESP32-S3 with native USB host
Quectel EG800Q modem
Tried in Arduino IDE → didn’t work
Switched to ESP-IDF, as it supports USB host better
What I need
Any working example of ESP32-S3 communicating with a USB modem (CDC/ACM).
How to select and open the AT port (modems usually have multiple ports: DM, NMEA, AT, and data).
Has anyone successfully sent AT commands via USB (not UART) to a Quectel modem?
Any tips, code samples, or guidance would be really helpful.
Thanks!
Note: I am new to IDF , so please explain in simple ways