[time-nuts] Prologix VRBOOT error

Prologix support at prologix.biz
Wed Jun 4 09:50:15 EDT 2008


We are testing a fix. I'll be in touch soon.


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Matt Ettus
Sent: Wednesday, June 04, 2008 12:40 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Prologix VRBOOT error

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
> 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
> USB cable is plugged in while the controller is connected to such an
> instrument. Since the pull-down is passive, this behavior could happen
> 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.


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