[time-nuts] FE-.5680A trimming resolution

Rob Kimberley robkimberley at btinternet.com
Tue Jan 31 16:14:59 EST 2012

If anyone is interested, I have just got hold of a PDF of the Technical Manual TM 5680-0211 for 5680A series Rubidiums. 
Please contact me off list for a copy (1M, so too large to post on time-nuts at febo.com)

Rob Kimberley

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Attila Kinali
Sent: 31 January 2012 20:47
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] FE-.5680A trimming resolution

On Tue, 31 Jan 2012 21:06:04 +0100
Javier Herrero <jherrero at hvsistemas.es> wrote:

> El 31/01/2012 20:43, Attila Kinali escribi :
> > My current progress is that the uC i wanted to use does not do what 
> > i want. Can anyone recommend a uC with 32bit timers and IEEE 1588 support?
> You can have a look on these
> http://www.ti.com/mcu/docs/mculuminaryfamilynode.tsp?sectionId=95&tabI
> d=2597&familyId=1756 Some of them have IEEE-1588, like the LM3S9B96

This was exactly the device i intended to use.
But it doesnt really have 32bit timers. They cascade two 16bit timers to get 32bit, but then all kind of restrictions apply which make the timers unusable. And when using 16bit timers, i'll get an overflow every 800us (at 80MHz clock).

I browsed trough the internets and could find the following devices:

LPC18xx (NXP): 
Look nice, but still in development or early production.
I especially like that they (will be) are available in a 200 pin QFP.
This would enable to use all the functions of the chip while still being able to solder one by hand.

K60 (Freescale): Hell of a confusing documentation. Also quite new.
Have only 16bit timers. A big issue is that they have a crypto unit on chip, which makes them export restricted. Ie the only way to buy them is from a local distributor which makes them expensive.

STM32-F2/F4 (ST): ST doesn't want to give me the documentation to those.
(website fails w/o error message)

I havent found any other chips yet. Sofar the options i see are:
* wait for the LPC18xx become available in quanities (can take a year)
* Use a LM3S9B96 together with a small FPGA to implement the counter functions.

Any hints appreciated

			Attila Kinali

Why does it take years to find the answers to the questions one should have asked long ago?

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