[time-nuts] Fw: Tbolt LCD Monitor - No DAC reading

[shalimr9 at gmail.com]

Forgot to copy the list...

Didier KO4BB

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

-----Original Message-----
From: shalimr9 at gmail.com
Date: Thu, 12 May 2011 13:07:13 
To: David Bobbett<d.bobbett at tiscali.co.uk>
Reply-To: shalimr9 at gmail.com
Subject: Re: [time-nuts] Tbolt LCD Monitor - No DAC reading

I will check but I believe my 3 TBolts all return positive voltages for the DAC.

The routine should handle negative voltages, but without having an actual data stream to check against, I can't tell for sure. 

If so, I may need someone who actually gets a negative voltage to send me the actual string returned from the TBolt. I will send you a piece of software that will capture it and save the data in binary to a file which you could then email back to me. That software is not written, and I am quite tied up at the moment, but I should be able to get to it in the next few days.

If you run Linux, it probably would be easier with a shell script but I am running an old kernel here (2.2.6), so I am not sure whatever I come up with would work on your machine.

If anyone has GPSMon displaying a negative DAC voltage, please let me know too.

Didier KO4BB

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

-----Original Message-----
From: David Bobbett <d.bobbett at tiscali.co.uk>
Date: Thu, 12 May 2011 13:23:16 
To: <shalimr9 at gmail.com>; Discussion of precise time and frequency measurement<time-nuts at febo.com>
Subject: Re: [time-nuts] Tbolt LCD Monitor - No DAC reading

Well just in case this helps, the DAC on my Tbolt is currently reading  
-0.056013V.  As before, it shows up OK on Tboltmon.exe and Lady Heather, 
reads all zeroes on the LCD monitor.

And just in case it is of any use, my Tbolt details from LH are:

App:  3.0     27 Jun 2002
GPS:  10.2   14 Nov 2001
Mfg:  10.00 24 Mar 2003
Ser:    0.80253721

I would have thought 5 minutes of testing would be more than adequate, I 
usually work on the principle that if there's no smoke it must be 
working fine  ;-)

David, G4IRQ



On 12/05/2011 11:46, shalimr9 at gmail.com wrote:
> The DAC voltage routine is the worst hack I have ever come up with (that was a close call....)
>
> The processor is an 8051 and the SDCC compiler I used does not have the floating point math library, so I had to decode the DAC voltage "by hand" and it is quite possible that the routine breaks down for some DAC values which I did not encounter here (I have 3 TBolts).
>
> I would be surprised if any bug could have survived the stringent 5 minutes of testing I subjected this project to but who knows... :)
>
> I will look at it. I also have a version of the code compiled with a different compiler (Keil) to try if someone wants to, but I doubt the problem is with the compiler.
>
> For those who have seen the wiki page for the GPSMon project, there is a new firmware version which can display local time (compensates for GPS offset, time zone and DST). However, the DAC routine is unchanged.
>
> Didier KO4BB
>
> ------Original Message------
> From: Mark Sims
> Sender: time-nuts-bounces at febo.com
> To: Time-Nuts
> ReplyTo: Time-Nuts
> Subject: [time-nuts] Tbolt LCD Monitor - No DAC reading
> Sent: May 12, 2011 2:56 AM
>
>
> I have a sneaking suspicion that I know what is going on... 
>
> Ages ago I sent the code for my first TSIP parser to someone (can't remember who...  was it Dieder?) who was going to use it in a microcontroller based tbolt monitor.  Fluke's monitor is just a lift of that design.  Well,  my code had a bug in the DAC message processor.  If I remember correctly it was something like reading the DAC value as a single precision number,  but the tbolt was sending a double precision number (or the other way around). 		 	   		
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> Sent from my BlackBerry Wireless thingy while I do other things...
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