[time-nuts] Tbolt and iCruse readout problem - any ideas?

Wed Aug 18 15:24:48 UTC 2010

"there doesn't seem to be any logical reason why the DAC data would be any different."

That is the kind of thinking I do often, and usually end up kicking myself in the butt later for :)

It could be that the serial data is corrupted during the transmission of the DAC value because of a particular bit pattern. It is not like the *design* of the RS-232 converter is bullet-proof... I had a very similar problem here at work just a week ago for the exact same reason (cheap RS-485 to RS-232 converter messed up one particular type of message, but worked well for over a year prior to that)

I have nothing else to offer, nobody else has reported this problem, and as I pointed out earlier, the code is basically the same that is displaying the temperature.

Another possibility is that the chip's firmware may be corrupted, in which case it may need to be reflashed.

Other than that, I don't know.

When facing something apparently illogical, do not exclude possible causes simply because they are improbable... If the solution were where you expected it, it would be already fixed, and if there were no problem, we would not be having that conversation :) Look under all the stones, not just those that look to be about the right size.

Didier

------------------------ 
Sent from my BlackBerry Wireless thingy while I do other things...

-----Original Message-----
From: David Bobbett <d.bobbett at tiscali.co.uk>
Sender: time-nuts-bounces at febo.com
Date: Wed, 18 Aug 2010 16:03:22 
To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
Reply-To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: Re: [time-nuts] Tbolt and iCruse readout problem - any ideas?

  Hi Didier,

No - the display reads "DAC V: 0.0000" on the iCruse LCD, all the other 
data (including temperature) displays normally and correctly. So it is 
only that part of the data which doesn't seem to be decoded and 
displayed correctly. The really odd thing is that the DAC V value can be 
seen in Tboltmon.exe, although I realise that that particular program 
also sends data to the Tbolt, which the iCruse does not.

The reference to the RS232 resistors was in the context of the 
discussions regarding whether the values in the iCruse are correct -  
but of course if all the other data is being received correctly, there 
doesn't seem to be any logical reason why the DAC data would be any 
different.

Thanks for the reply, but I'm still puzzled!

David, G4IRQ

On 18/08/2010 12:33, Didier Juges wrote:
> When you say "will not display the DAC V value", do you mean the display is
> blank, or it displays garbage?
>
> Interestingly, the code that displays temperature and DAC voltage is
> essentially the same, the only difference being which part of the data
> string received from the Thunderbolt is processed, so it is hard to imagine
> why one would work and not the other, unless the data received from the TB
> is corrupted in the part that should contain the DAV value, and the
> conversion routine fails.
>
> If you have doubts that the serial interface may not be working (I am not
> sure about what missing resistor you are talking about), fix that first and
> try again.
>
> Looking at the serial stream with a scope may help diagnose such problem.
>
> Didier KO4BB
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of David Bobbett
> Sent: Wednesday, August 18, 2010 4:23 AM
> To: time-nuts at febo.com
> Subject: [time-nuts] Tbolt and iCruse readout problem - any ideas?
>
>    Hi all,
>
> Having struggled in vain to solve this problem, I thought I  would make a
> plea for help as my first posting to Time Nuts . . . so here goes!
>
> I have a Tbolt with v3.00 firmware which works fine with the Tboltmon.exe
> V2.60 and Lady Heather software. It also works fine with the iCruse Tbolt
> LCD monitor - except that the monitor will not display the "DAC V" value,
> all the other values are displayed without a problem.
> The iCruse is the later version which has had the PIC voltage conversion
> done, but not the RS232 input resistor mods.
>
>
> I have two questions really:
>
> 1) Is there a setting which I need to change in my Tbolt using Tboltmon.exe
> to get this to work?
>
> 2) Does anybody on Time Nuts have an iCruse which shows a negative value for
> the "DAC V"?
>
>
> As far as I can see, there are 3 options: a) there is a configuration
> problem, b) the iCruse doesn't display negative values for DAC V, c) my
> iCruse is faulty. I've pretty much run out of ideas on this one, so any
> suggestions would be greatly appreciated!
>
> Regards,
>
> David Bobbett, Milton Keynes, UK.
>
>
>
>
>
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