EC21-EUX miniPCIe module enters Qualcom QDL mode


I have a EC21-EUX module that identifies itself correctly as USB device 2c7c:0121 in a x86 PC.
When used in a ARM based board, it’s identified as USB device 05c6:9008, a Qualcomm Gobi Modem in QDL mode. (see also thread: EP06-E over USB identified as 05c6:9008 a similar issue but different module).

Can you please tell me which pins put the EC21-EUX module into the QDL mode?
Do W_DISABLE# and PERST# have a on-module pull up to 1.8V?

Best regards,

Developers can pull up USB_BOOT to 1.8 V before VDD_EXT is powered on, and then
The module will enter the emergency download mode when it is turned on. In this mode, the module can be upgraded through the USB interface.

Hi Felix,

I’d like to use the module in normal mode.
I think it enters boot mode (05c6:9008).

  • Which pin is USB_BOOT on this module?


HI Lothar
I will provide you with a hardware design manual, please check
Quectel_EC21_Series_Hardware_Design_V1.9.pdf (1.6 MB)

Hi Felix,

thanks for the module documentation, but we’re using the miniPCIe module, not the EC21 module itself. So I have no idea how the boot pin is wired on the miniPCIe module.
Can you please let me know which pin is connected to the boot mode (USB_BOOT pin) and if there is a pull-up/-down on the module for this pin?

Best regards,

Solution: tape pins 3 and 5 on the M.2 connector.