[time-nuts] TAPR TADD-2 PIC frequency divider

John Ackermann N8UR jra at febo.com
Sat May 23 11:11:59 UTC 2009


The code is available at http://www.tapr.org/~n8ur/PIC_Code in both 
source and object form.  The "03-2009" version is what is shipping on 
the current TADD-2s.

The "04-2009" version is a slight update from Richard McCorkle that 
changes the way the ARM and SYNC LEDs work, and also allows selecting a 
50% duty cycle output (instead of 20%) as a compile time option. 
Otherwise there are no changes (ie, no bug fixes).

John
----

Samuel D. [x86/CPC] said the following on 05/22/2009 07:38 PM:
> Another question about the TADD-2 PIC divider : they said on main page the
> source code for the pic will be released in open source. Does anyone know if
> the code is available somewhere ?
> 
> 
> -----Message d'origine-----
> De : time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] De la
> part de Magnus Danielson
> Envoyé : samedi 23 mai 2009 01:33
> À : Discussion of precise time and frequency measurement
> Objet : [time-nuts] TAPR TADD-2 PIC frequency divider
> 
> Fellow Time-nuts,
> 
> I acquired myself two TAPR TADD-2 PIC frequency dividers as soon as they 
> hit the list as orderable. Tonight I had the pleasure of completing the 
> first one.
> 
> For a beginner, this kit should be fairly simple. You need to have some 
> ability to solder and read resistor and capacitors, even if most 
> capacitors comes in separate bags (pretty neat brown bags, but hard to 
> open without ripping the lid partly off). The manual could give better 
> hints for the beginner, but it is nothing major at all.
> 
> Since I fail to fall into the beginner group, I must say that it was 
> pretty straight forward to build it. The double-sided, silkscreened and 
> plated hole PCB made this as simple as any other modern kit and it is 
> easy to make the mounting look good. I was supprised how well my 
> resistor-leg bending was still up to speed and accuracy as they all went 
> in quickly and smoothly. Everything went very smoothly.
> 
> So, at last... everything mounted and time to power up. Without input it 
> sits there quitetly. I hooked it up to the time-base output of my SR-620 
> and it kicked alive directly. 10 kHz, 1 kHz, 100 Hz, 10 Hz, 1 Hz and PPS 
> all just ticked away as expected. I hooked over to a 5 MHz source, the 
> OCXO (TOYO oscillator of unknown specs) from an Ericsson AXE-10 station 
> that I keep heated at the labbench with a BNC hanging free, and sure 
> enought everything was half-rate including the PPS LED (very useful), 
> but just unplugging the 5/10MHz jumper fixed that quick enought.
> 
> A few items of criticism is in place, from a practical point of view. 
> The TADD-2 does not perfectly match the TAPR TADD-series box. I was able 
> to sneak out the PPS through the DC input hole, and the ARM and SYNC 
> LEDS is way in there, so a similar approach was not possible. The 5/10 
> MHz jumper should possibly be made into a toggle-switch. None of those 
> fits the casing, but using one of the DB9 holes should fit it nicely. 
> The other DB9 hole could be fitted with a suitable DB9 connector for 
> power. None of these things is a show-stopper, but of mild details which 
> could have been made better and very simple hacks will allow for a more 
> versatile setup, for those wishing to use their TADD-2 as a lab-device, 
> where as for fixed setups it is of close to no consequence.
> 
> I only made a quick attempt to measure jitter, but it is way down there 
> around ps or so. It was just an indicator measurement anyway. I will 
> make some more propper measurements and analysis.
> 
> Regardless, I think it is a nice kit and should allow for easy 
> lab-ability for most time-nuts. I particularly like the simultanous 
> outputs which is jumperable to suitable outputs and the 5/10 MHz jumper. 
> The PPS LED allows for a quick view and the ARM/SYNC should allow for 
> synchronisation. It fairly well fills a gap in my set of gear and should 
> do that for others too. Doing picket fence exercises becomes trivial 
> with one of these.
> 
> Good work John, Tom and others that feel involved.
> 
> Cheers,
> Magnus
> 
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