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[time-freq] Reflock II observations

BOBBY ba at bobby.net
Sun Nov 20 18:14:02 UTC 2005

Hi Folks,
This kit is starting to feel a bit like walking around blindfolded in a room full of shin high sharp corners...

I'd like to offer a couple of observations, ideas, suggestions, ramblings ?

First: I built a Byteblaster clone from a schematic found at:
It's the same connections as Altera's schematic, but much easier to read w/ connector outlines.
I added a Berg type jumper/selector to allow the 74LS244 Vcc to be optionally powered externally,
in my case I set it to 4.5V but suspect 5.0V would have made no difference.

The Quartus II web version doesn't offer Byteblaster as an option, but the Byteblaster II choice
seemed to work fine. I say "seemed" because I only have the Quartus program to go by at this point.
Which brings me to the next suggestion.

It would be useful to have a simple test download that continously toggled one or both of the leds.
They would serve to indicate that much of the PWB is assembled correctly, the CPLD is functional, 
it was correctly programmed, and the leds were installed the right way (not obvious from silkscreen). 
Encouraging and useful to know before taking on the task of getting sources to lock, which can  
have problems all it's own.

The kit docs still seem a little skimpy (multiple silkscreen copies excepted), written toward a 
reader already very familiar with Altera's products and this design in particular. As an example
I have an email that in part says:
r2_flex_01 - Reflock II flexible frequency (configured by the R and N
Divisor jumpers)
r2_refpps_01 - Reflock II 1PPS
r2_enhpps_20 - Reflock II enhanced 1PPS

Each of the files has

*.txt - gives the jumper settings for the configuration
*.pin - gives the pins numbers to the pin names
*.pof - this is the hex file loaded into the CPLD

I'm happy for help offered, however here  is the .text file for the r2_enhpps_20

-- conf=00 locks to 50KHz multiples
-- conf=01 locks to 25KHz multiples
-- conf=10 locks to 12.5 KHz multiples
-- conf=11 locks to 10 KHz multiples

the lock detector is not working properly....
but this is the first time I had a chance
to see that code in action :)

note 1pps input is on P2 and REF input is left

pps_pol = 1 >> falling edge of 1pps is used
pps_pol = 0 >> rising edge of 1pps is used


Ouch!  What was that a coffee table ?

"conf=11 locks to 10 KHz multiples" I'm assuming this means to control my 10 MHz Rb osc, I would set the
N divider to 1000 and use conf=11. But nowhere tells me this, nor have I found any direction as to where
"conf=11" would be applied. Ditto for pps polarity.

73 Bobby k4bga


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