GSOC 2017 RTEMS-libbsd issue

Christian Mauderer christian.mauderer at
Wed Apr 19 15:05:24 UTC 2017

----- Ursprüngliche Mail -----
> Von: "赵 思晨" <zsc19940506 at>
> An: "Christian Mauderer" <christian.mauderer at>, "RTEMS" <devel at>
> Gesendet: Mittwoch, 19. April 2017 16:41:20
> Betreff: Re: GSOC 2017 RTEMS-libbsd issue

> Hi Christian Mauderer,
> 1. I haven't put these change in my git repo yet.
> 2.Yes, i verified that by the console output , the below snapshot :
> including some debug info. just forget it.
> [cid:4fb54908-2ff4-4098-9f94-6f2aa529babf]
> 3.The application i use is testsuite/usb01, i debug it, and it loop at the
> uhub_explore function in usb_hub.c, and didn't reach the umass_probe function.
> 4. I noticed that the pin USB1_DRVVBUS and USBx_VBUSIN is always low, so i think
> it can't detect the new device.
> Best Regards
> Sichen Zhao

Hello Sichen Zhao,

point 4 sounds like you found your problem. According to the schematics, there is a TPS2051 on the BBB to switch the power of the USB. This chip has an active high enable input. So USB1_DRVVBUS should be high.

For a quick try, you could connect a self powered hub. But sooner or later, you should just switch the pin on. Please note that it might would be a good idea to use it to reset the connected devices on a reboot.

Kind regards


embedded brains GmbH
Christian Mauderer
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