# EM7455 does not enumerate after at!reset

**URL:** https://forum.sierrawireless.com/t/em7455-does-not-enumerate-after-at-reset/17982
**Category:** MC/EM Series
**Created:** [October 17, 2019, 10:10pm UTC](https://forum.sierrawireless.com/t/em7455-does-not-enumerate-after-at-reset/17982 "2019-10-17T22:10:32Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![dchou4u](https://avatars.discourse-cdn.com/v4/letter/d/e9a140/32.png) [@dchou4u](https://forum.sierrawireless.com/u/dchou4u)
#### Post date: [October 17, 2019, 10:10pm UTC](https://forum.sierrawireless.com/t/em7455-does-not-enumerate-after-at-reset/17982/1 "2019-10-17T22:10:32Z")

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I have a EM7455 module running on my embedded Linux ARM board. I noticed that sometimes after doing a AT!RESET on the module, the module does not enumerate again after reset. Doing a dmesg on my Linux prompt, I see:

# dmesg

GobiSerial driver ttyUSB2: GobiSerial converter now disconnected from ttyUSB2  
Send ZERO CONF FAIL!  
GobiSerial 4-1:1.0: device disconnected  
GobiSerial driver ttyUSB1: GobiSerial converter now disconnected from ttyUSB1  
GobiSerial 4-1:1.2: device disconnected  
GobiSerial driver ttyUSB0: GobiSerial converter now disconnected from ttyUSB0  
GobiSerial 4-1:1.3: device disconnected  
GobiNet 4-1:1.8: eth3: unregister ‘GobiNet’ usb-0002:04:00.0-1, GobiNet Ethernet Device  
xhci\_hcd 0002:04:00.0: xHCI host not responding to stop endpoint command.  
xhci\_hcd 0002:04:00.0: Assuming host is dying, halting host.  
xhci\_hcd 0002:04:00.0: HC died; cleaning up  
usb 4-1: USB disconnect, device number 2

# 

Anyone know what is going on? Is my USB host driver dead?  
I am running Linux 3.6.5.

Thanks

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<div class="post-metadata">

### Author: ![mlw](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/mlw/32/3706_2.png) [@mlw](https://forum.sierrawireless.com/u/mlw)
#### Post date: [October 18, 2019, 3:34pm UTC](https://forum.sierrawireless.com/t/em7455-does-not-enumerate-after-at-reset/17982/2 "2019-10-18T15:34:40Z")

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@dchou4u,

This is probably going to be something with the USB hub, the firmware on the MC will enumerate the same time whenever it sees a host system and the USB hub on the host system will see a given device’s VID/PID when it tried to enumerate and from this the host system will know to use/invoke the driver for the given VID/PID.

Regards

Matt

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<div class="post-metadata">

### Author: ![dchou4u](https://avatars.discourse-cdn.com/v4/letter/d/e9a140/32.png) [@dchou4u](https://forum.sierrawireless.com/u/dchou4u)
#### Post date: [October 18, 2019, 3:51pm UTC](https://forum.sierrawireless.com/t/em7455-does-not-enumerate-after-at-reset/17982/3 "2019-10-18T15:51:15Z")

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Thanks for the reply.

Is there a way for me to release the GobiNet and GobiSerial devices after issuing the AT!RESET command? Perhaps this allows the host to orderly release the devices without the sudden shock of handling the disappearance of the modem.