AnsweredAssumed Answered

single USB VBUS USB2 not working correctly

Question asked by Forum User on Aug 3, 2017
Latest reply on Aug 8, 2017 by Forum User

We have a custom board running Linux with USB1 used as external USB interface and USB2 used to connect a 3G/4G Modem.

Only USB_VBUS1 is connected to 4.7V, VUSB_CAP is at 3.2V.

 

In this situation the 3G/4G modem (high-speed device) does not enumerate in Linux environment.

 

When forced to enumerate again it is detected as full-speed device and not working properly.

usb 2-1: new full-speed USB device number 2 using ci_hdrc
usb 2-1: device no response, device descriptor read/64, error -71
usb 2-1: device no response, device descriptor read/64, error -71

 

When the voltage at USB_VBUS1 is increased to 4.9V it enumerates correctly.

 

When the modem is connected to USB1 it enumerates correctly.

usb 1-1: new high-speed USB device number 2 using ci_hdrc
option 1-1:2.2: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB0
option 1-1:2.3: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB1
option 1-1:2.4: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB2
option 1-1:2.5: GSM modem (1-port) converter detected
usb 1-1: GSM modem (1-port) converter now attached to ttyUSB3

 

In uboot the device is detected correctly on USB2:

=> usb tree
USB device tree:
1 Hub (480 Mb/s, 0mA)
u-boot EHCI Host Controller

2 Hub (480 Mb/s, 0mA)
| u-boot EHCI Host Controller
|
+-3 Vendor specific (480 Mb/s, 500mA)
HUAWEI Technology HUAWEI Mobile 0123456712ABCA17

 

I'm running out of ideas here so any suggestion is welcome.

 

Best regards,

Ralf

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