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

Attila Kinali attila at kinali.ch
Tue Jan 31 15:47:15 EST 2012


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

> El 31/01/2012 20:43, Attila Kinali escribió:
> > 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&tabId=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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