Tofu Board unable to find SIMCOM7600G or Quactel EC25-E modem


We recently purchased a Tofu board for a customer project as this board seems to be the closest match to the original BalenaFin board which is now discontinued. The project requires 4G and GNSS connectivity and as such we are using the M.2 mini PCIe adapter to connect our modem.

The device is powered with a 12V 10A power supply, and the USB interface through M.2 is enabled with the following parameters:

"vc4-fkms-v3d", "dwc2,dr_mode=host"

The output of lsusb -t gives the following, indicating that the hub is available:

/:  Bus 01.Port 1: Dev 1, Class=root_hub, Driver=dwc2/1p, 480M
    |__ Port 1: Dev 2, If 0, Class=, Driver=hub/4p, 480M

We have attempted to connect both an SIMCOM7600G and Quactel EC25-E modem but unfortunately we cannot get either of them to work. A system connection has been configured to look like this, just like we would on other devices:





The modem manager is unable to find any devices, and lsusb only shows the hub itself. Looking at dmesg we see several errors in relation to a connected USB device.

[  215.891043] usb 1-1.1: new full-speed USB device number 3 using dwc2
[  215.975006] usb 1-1.1: device descriptor read/64, error -32
[  216.163051] usb 1-1.1: device descriptor read/64, error -32
[  216.351132] usb 1-1.1: new full-speed USB device number 4 using dwc2
[  216.435052] usb 1-1.1: device descriptor read/64, error -32
[  216.623095] usb 1-1.1: device descriptor read/64, error -32
[  216.731171] usb 1-1-port1: attempt power cycle
[  217.335051] usb 1-1.1: new full-speed USB device number 5 using dwc2
[  217.751130] usb 1-1.1: device not accepting address 5, error -32
[  217.831067] usb 1-1.1: new full-speed USB device number 6 using dwc2
[  218.247096] usb 1-1.1: device not accepting address 6, error -32
[  218.247308] usb 1-1-port1: unable to enumerate USB device

All in all, we’re unable to get the modem working on the Tofu board, and are wondering if perhaps we missed something. We have also measured the M.2 test pads and there is 3.3V available.

Both modems have been installed in a Compulab IOT-GATE-iMX8 and are fully functional on that device, so it’s not a hardware fault related to the modems themselves.

@mrrobot, could it be a hardware failure with the Tofu board itself, or have we missed some important step in the documentation?

Any help is appreciated!


Hi Jonathan,

We’ve had issues with this adapter board production and the PCB tolerances are a bit off. This allows it to be off-centered in the m.2 slot and may result in improper contact.
Can you try plugging it again to make sure the adapter is well-centered in its socket?

Sorry for this issue, let us know if we can help further.


We’ve attempted this several times, but unfortunately there is no way we can make it stick. My colleague was fiddling with it a little bit and at some point it looked like we got some contact, but it’s incredibly glitchy. Has this production problem been resolved yet?

Thank you for your feedback and sorry for the trouble.
We will ship a new adapter to you from our new production where the issue has been solved, free of charge.
We hope this will help solve the problem swiftly.
Best regards

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Thank you! Can you find our order or do we need to email you separately? :blush: