EC200U Powers On Successfully but USB Is Not Detected by PC

IoT Modules LTE Standard Module
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1

Hello Support Team,

I am using an EC200U module on a custom hardware design and am experiencing an issue with USB detection.

Observations:

  • The EC200U powers on successfully.

  • The STATUS pin goes high and the STATUS LED turns ON after asserting PWRKEY, indicating that the module has booted.

  • The module remains powered and does not shut down unexpectedly.

  • USB_VBUS is connected to 5 V.

  • USB_DP and USB_DM are connected to the USB connector.

  • When the USB cable is connected to a Windows PC, no new COM ports appear in Device Manager.

  • No unknown USB device or Quectel USB device is detected by Windows.

  • The issue is reproducible on multiple USB ports and cables.

I would appreciate guidance on the following:

  1. Are there any required hardware connections, pull-ups, pull-downs, or configuration pins needed for USB enumeration on the EC200U?

  2. Is there any firmware configuration that could disable the USB interface by default?

  3. Is it possible to verify USB functionality through the debug UART?

  4. Are there recommended checks to confirm that the USB subsystem has initialized correctly after boot?

Please let me know if additional information such as schematics, power measurements, or firmware version is required.

Thank you for your assistance

2

Hi there,
Most probably there is no driver installed in the PC. You can install the driver below based on your PC’s OS.

Windows: Quectel_Windows_USB_Driver(U)_V1.2_EN (1).zip
Linux: Quectel_Linux_USB_Serial_Option_Driver_V1.1.tgz

You can also refer to the Hardware design document as per attached below:

EC200U Reference Design.zip

3

Hello there,

Thank you for your response.

I have already installed the Quectel Windows USB driver on my PC. To verify the driver installation, I connected another EC200U module, and it is detected correctly by Windows with the expected COM ports appearing in Device Manager.

However, the EC200U mounted on my custom hardware is not detected at all. The module powers up correctly, the STATUS pin goes high, and the STATUS LED turns ON after PWRKEY is asserted, indicating that the module has booted successfully. Despite this, Windows does not detect any USB device when the module is connected through USB.

Since the driver and PC setup have been verified using another working EC200U module, I suspect the issue may be related to the hardware design or USB interface initialization on the custom board.

Could you please advise on the following:

  • Are there any specific signals or test points that should be checked to verify USB initialization?

  • Can USB functionality be verified through AT commands on the UART interface?

  • Are there any hardware requirements beyond VBUS, USB_DP, and USB_DM that could prevent USB enumeration?

  • Is there any AT command that can confirm whether the USB interface is enabled in the firmware?

Please let me know if you need anything else from my side.

Thank you for your support.

Best regards,
kazuki