# MC7455 not recognized at boot **URL:** \ **Category:** MC/EM Series\ **Created:** [January 11, 2018, 10:17am UTC](https://forum.sierrawireless.com/t/mc7455-not-recognized-at-boot/9735 "2018-01-11T10:17:22Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![massimilianoraspante](https://avatars.discourse-cdn.com/v4/letter/m/a9adbd/32.png) [@massimilianoraspante](https://forum.sierrawireless.com/u/massimilianoraspante)\ **Post date:** [January 11, 2018, 10:17am UTC](https://forum.sierrawireless.com/t/mc7455-not-recognized-at-boot/9735/1 "2018-01-11T10:17:22Z")
Hello I’m working on a IoT project using MC7455 modem as communication module. The host board is the IMX7 DUAL COM BOARD di Embedded Artists [https://www.embeddedartists.com/products/com/imx7dual\_com.php](https://www.embeddedartists.com/products/com/imx7dual_com.php) I performed the following test steps: 1. Board powered off – Modem installed on PCIe interface. 2. Board power on – kernel starts but modem is not recognized. 3. After login lsusb command is sent, modem not recognized. 4. Modem removed from the PCIe interface and inserted again Result: usb 1-1.1: new high-speed USB device number 3 using ci\_hdrc usb 1-1.1: config 1 has an invalid interface number: 8 but max is 4 usb 1-1.1: config 1 has an invalid interface number: 10 but max is 4 usb 1-1.1: config 1 has no interface number 1 usb 1-1.1: config 1 has no interface number 4 sending again lsusb: Bus 001 Device 003: ID 1199:9071 Bus 001 Device 002: ID 0424:2514 Bus 001 Device 001: ID 1d6b:0002 Sending usb-devices: T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=480 MxCh= 1 D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=01 MxPS=64 #Cfgs= 1 P: Vendor=1d6b ProdID=0002 Rev=04.01 S: Manufacturer=Linux 4.1.15-2.0.3+geb0b90b ehci\_hcd S: Product=EHCI Host Controller S: SerialNumber=ci\_hdrc.1 C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=480 MxCh= 3 D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=02 MxPS=64 #Cfgs= 1 P: Vendor=0424 ProdID=2514 Rev=0b.b3 C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=2mA I: If#= 0 Alt= 1 #EPs= 1 Cls=09(hub ) Sub=00 Prot=02 Driver=hub T: Bus=01 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 3 Spd=480 MxCh= 0 D: Ver= 2.10 Cls=00(\>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=1199 ProdID=9071 Rev=00.06 S: Manufacturer=Sierra Wireless, Incorporated S: Product=Sierra Wireless MC7455B Qualcomm® Snapdragon™ X7 LTE-A S: SerialNumber=LQ73958578031020 C: #Ifs= 5 Cfg#= 1 Atr=a0 MxPwr=500mA I: If#= 0 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none) I: If#=10 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none) I: If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none) I: If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=00 Driver=(none) I: If#= 8 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none) So my questions are: Why the modem is not recognized automatically at power on? According to the logs above, Is the modem recognized correctly after the hotplug? Searching on Sierra Wireless forum I found this thread [https://forum.sierrawireless.com/t/mc7455-usb-device-disconnects-immediately/9415/1](https://forum.sierrawireless.com/t/mc7455-usb-device-disconnects-immediately/9415/1) Could it be a problem related to USB3 pins? Thanks in advance Massimiliano ---
**Author:** ![jyrki](https://avatars.discourse-cdn.com/v4/letter/j/77aa72/32.png) [@jyrki](https://forum.sierrawireless.com/u/jyrki)\ **Post date:** [January 14, 2018, 9:24am UTC](https://forum.sierrawireless.com/t/mc7455-not-recognized-at-boot/9735/2 "2018-01-14T09:24:14Z")
Hi, At least in my case MC7455 was not recognized by Qotom minipc board at all. I turned out to be the USB3 pin mapping as described here: [https://techship.com/faq/38/](https://techship.com/faq/38/). Your usb-devices looks same as what I have. Jyrki