[time-nuts] Prologix VRBOOT error

Matt Ettus boyscout at gmail.com
Wed Jun 4 03:39:38 EDT 2008

On Tue, Jun 3, 2008 at 5:31 PM, Prologix <support at prologix.biz> wrote:
> Short version:
> Connect USB cable before connecting GPIB, and leave USB connected and
> powered.

That isn't realistic for my setup.

> Long version:
> On startup, if one of the MCU I/O lines is pulled low, the controller will
> enter firmware update mode. As it happens, this I/O line is also one of the
> GPIB bus signals. Some instruments seem to have stronger pull-down on the
> bus lines than others. The controller may enter firmware update mode, if the
> USB cable is plugged in while the controller is connected to such an
> instrument. Since the pull-down is passive, this behavior could happen even
> if the instrument is powered down when connecting USB.

Honestly, this sounds like a serious design flaw to me.  I have 5 GPIB
instruments, and 3 of them cause this behavior.  If 3 pieces of test
equipment from 3 different manufacturers cause this behavior, it must
be pretty common.


More information about the time-nuts mailing list