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Divide by 10000000

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ludzinc:

--- Quote from: mikerj on May 31, 2017, 08:29:22 am ---
--- Quote from: blueskull on May 31, 2017, 07:49:45 am ---It all depends what you want to do with 1pps. If it is only to drive an alarm clock, then it is fine to do that with a MCU.
If you are actually going to feed it to a discipline clock generator which will use 1pps input to drive PLL in order to generate a perfectly phase aligned clock, then think twice. Your MCU is likely to generate quite some jitter that will ruin your output clock.

--- End quote ---

If you are clocking the micro from the GPS 10MHz clock, and the division is performed by a timer rather then software, then you are only adding the residual jitter from the hardware timer.  This isn't something you'd ever see specified in a datasheet,  do you have any numbers?

Disciplined clock sources perform a lot of averaging on the 1PPS signal anyway, so a small amount of jitter shouldn't be a problem.

--- End quote ---

*than

mikerj:

--- Quote from: ludzinc on June 01, 2017, 04:21:05 am ---
--- Quote from: mikerj on May 31, 2017, 08:29:22 am ---
--- Quote from: blueskull on May 31, 2017, 07:49:45 am ---It all depends what you want to do with 1pps. If it is only to drive an alarm clock, then it is fine to do that with a MCU.
If you are actually going to feed it to a discipline clock generator which will use 1pps input to drive PLL in order to generate a perfectly phase aligned clock, then think twice. Your MCU is likely to generate quite some jitter that will ruin your output clock.

--- End quote ---

If you are clocking the micro from the GPS 10MHz clock, and the division is performed by a timer rather then software, then you are only adding the residual jitter from the hardware timer.  This isn't something you'd ever see specified in a datasheet,  do you have any numbers?

Disciplined clock sources perform a lot of averaging on the 1PPS signal anyway, so a small amount of jitter shouldn't be a problem.

--- End quote ---

*than

--- End quote ---

Sorry, don't quite understand?

Marco:
He corrected you on using then instead of than, without properly quoting only the relevant part.

dgminala:

--- Quote from: bingo600 on May 31, 2017, 03:58:50 pm ---The late Ulrich B , made an AVR PPSDIV (Picdiv lookalike)

The M8 version ought to be easy to adapt to an arduino
http://www.ulrich-bangert.de/html/downloads.html

/Bingo

--- End quote ---

Sorry to resurrect an old thread, but I'm hoping to get a bit of information about the AVR PPSDIV code that Ulrich B posted for a decade frequency divider using  AVR and Mega8 devices.  I'm a complete newbie to the world of microcontrollers and am clueless about assembly code. At this stage of my life, I'm not sure that I want to learn to write it.
There seems to be no documentation about his rewrite of Tom van Baak's project.  Can anyone tell me which model(s) of AVR and Mega8 the code can be written into and work as described?  I'm assuming that the code is specific to only one or very few models.

I have a couple projects in mind that would seriously benefit from a single-chip solution to a decade divider that would, starting with a 10MHz input, provide decade frequency outputs from 1MHz to 1Hz (simultaneously). I realize that the Ulrich B project doesn't provide a 1MHz output, but I could live with an extra divider chip if I could get the rest of the decades in a single chip.  But which chips can I use with this code?

Thanks for any advice,
Dave M


bingo600:
I think i assembled (compiled) it for a Tiny84 here  (Not tested i real Hw)
https://www.eevblog.com/forum/projects/lars-diy-gpsdo-with-arduino-and-1ns-resolution-tic/msg2042386/#msg2042386

T84 code here
https://www.eevblog.com/forum/projects/lars-diy-gpsdo-with-arduino-and-1ns-resolution-tic/?action=dlattach;attach=597535

This one ought to run on a M8 (Full port D) - You can't use it on an Arduino (board) , as the Arduino Serial port are on Port D  , but you prob. could on a "bare M328"
http://www.ulrich-bangert.de/PPSDividerMega8.zip

/Bingo

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