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When I reboot my Beaglebone-black the USB modem does not start up. I need to unplug the modem, reboot the bbb and plug it for it to work. How do I fix this?

I suspect that I need to power cycle USB 1 bus.

With Armstrong I could use devmem2, but this is not available on the Debian image.

Please note that it is common for GSM modems to hang and they sometimes need to be reset once a day on embedded devices.

How do I achieve this with my bbb and Debian?

Normal power cycle with USB modem inserted:

$ lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Modem plugged in only after reboot:

$ lsusb Bus 001 Device 002: ID 114f:1234 Wavecom Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub 
/sys/bus/usb/devices/usb1# echo 0 > bConfigurationValue

brings the device down, but I cannot get it on again?

(I have tried /sys/bus/usb/devices/usb1# echo 1 > bConfigurationValue)

This is on clean Debian 2015-03-01 image, will try with the updated one next...

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  • Try echo 0 > /sys/bus/usb/devices/usb1/1-1/bConfigurationValue, then echo 1 to the same file. Commented Apr 13, 2022 at 13:47

1 Answer 1

Reset to default
0

You can drop a device from the bus and add it back by writing 0 then 1 to /sys/bus/usb/.../bConfigurationValue. More certain would be to call libusb_reset_device() using a simple C program.

common for GSM modems to hang and they sometimes need to be reset once a day

Consider better hardware.

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  • Answer updated with tries. Commented Jun 8, 2015 at 15:37

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