No reaction of brand new EM9291, when using (even different) M.2 USB adapters (e.g. Waveshare USB TO M.2 B KEY)


I just received 2 brand new EM9291. I connected one of them to a M.2 USB adapter,
(e.g. )
which work great for 5G modules from other manufacturers.

I connected the USB side to a PC and Raspberry Pi (USB 3.x and USB 2.x),
but EM9291 is not detected. No life of sign.

I tried different M.2 USB adapter, but all behave the same.

After some searching I found it could be PCIE_DIS, which I assume is simply not connected.
Can someone confirm this problem and is it PCIE_DIS or something else?

I found this is no new problem:

What was/is the solution for this?
Is pin 20 of M.2 using as PCIE_DIS something proprietary? Or does it follow some offical ruling?
In an upcoming hardware it could perhaps be possible to connect it to some signal,
but how about different devices from different manufacturers? Could there be a collision because of this signal on pin 20?

Is there perhaps some different solution? One, without needing to change the hardware…

Many thanks!

Best regards,

yes, you need to check PCIE_DIS signal

PCIE_DIS (on pin 20 on M.2 connector)
And as I read in other posting VBUS_SENSE (on pin 22 on M.2 connector)

Can you tell me, if two of the test points on the back of the EM9291 are connected to M.2 pin 20 and 22?
This would help me soldering two wires, instead of the difficult M.2 connector.
Same for checking/measuring for certain signals.

You can use a multimeter to confirm, right?

Thank you for your help!

You (Sierra Wireless) want to sell radio modules B2B and give professional service via a forum,
and ask me to use a multimeter to find out which test point is connected to what signal?
Suggest reverse engineering your radio modules? Is this your serious suggestion?

Sierra Wireless has schematic of EM9291 to look for this information, at least some of your hardware colleagues.
If this information is not public, just tell it.
This question will come of up more than once in future, so I think even a technical note (or similar)
on “hardware bringup” would be helpful, especially when using signals, which no other
manufacturer seems to be using.

I found the same suggestion for the previous product EM9190:

It would be nice if you could clarify this!

those test points are for internal usage only, probably you need to rework on the host PCB.

Dear Matrin,

I am facing exactly the same issue as you did. Could you let me know if you managed to solve it?


You need to have an adapter which has pin 20 and pin 22 connected.
(I am not sure, but I think I used this one:
USB3 to M.2 Key B 4G 5G Modem Adapter Enclosure with SIM Card Slot – V7 – Sierra Quectel Fibcom SimCOM 5G Supported - The Wireless Haven or similar)
One of them switches M.2 to USB.
Then you should see the module via USB.
And don’t forget to use Sierra Wireless delivered proprietary drivers afterwards.

A suitable power supply is the next topic (which I faced with a 5G module of a different manufacturer).

Perhaps have a look if Sierra Wireless offers a Evalboard/Dev Kit. Could be worth investing!