accurate timing

Questions on other types of hardware and getting it talking to the ARM CPU
basicchip
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accurate timing

Postby basicchip » Mon Jul 07, 2014 7:11 pm

>from the help line
>I have used one of your 50mhz chips several years ago and found it to be a very nice platform for personal projects. that chip has served me well and i\'m looking to upgrade to the arm7 60mhz board.

>My new project requires that I have a very precise timer. As such, what kind of timing could I expect to get out of the arm7 60mhz? Would there be a reason to go with the 50mhz boards instead? If I could get down to 5 or 10 nanoseconds accurately that should work. I did not see this info on the website, but it doesn\'t mean its not available.

The most accurate timing you can get from a 60 MHz CPU is 1/60 MHz or 16 nsec, and that would require reprogramming the PCLK setup for the TIMER hardware as it normally is running at 1/4 that rate to save power.

In addition most of our boards are using the internal RC oscillator which is trimmed at the factory to be 1% accurate. All our current boards allow a crystal to be added for better accuracy, typical crystals are 0.01 % accurate.

We will be introducing an LPC4330 based board in the next month or so that will have a crystal installed and will be running at 200 MHz, which would give you 5 nsec timing accuracy when using the TIMER hardware.

olzeke51
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Re: accurate timing

Postby olzeke51 » Wed Jul 09, 2014 8:27 pm

Is it too early to find out what chip configuration you are using --
FBD , FET, 100, 144 etc. the NXP site lists different configs.
I am trying to figure out what Docs to look at at NXP.
Thanx

basicchip
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Re: accurate timing

Postby basicchip » Wed Jul 09, 2014 8:40 pm

It will be the LQFP144, there is actually a grainy picture of it on this page (lower left hand corner).

http://www.coridium.us/custom5.php

This was actually designed quite a while ago to take advantage of the SGPIO for custom projects, since then we added a micro SDcard socket, and are still debating whether to put the JTAG connector on.

olzeke51
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Re: accurate timing

Postby olzeke51 » Wed Jul 09, 2014 9:07 pm

has there been much consideration of putting Arduino shield configuration back to back ??
the second shield wouldn't have the pins assigned to specific digital/analog pins like the
regular shield is on many of your 'Pro' boards--
had this thought before you mentioned the micro-SD card --

basicchip
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Re: accurate timing

Postby basicchip » Wed Jul 09, 2014 9:20 pm

Not quite sure what you mean by "back to back". This board connects to the standard Arduino pin array, and then connects every useful pin to a n array of 5x18 holes on 0.1" centers.

olzeke51
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Re: accurate timing

Postby olzeke51 » Wed Jul 09, 2014 9:52 pm

oooooo oooooo x ooooo (ad)------------------------]
ard here main x 2nd ard here your array |
' <- x -> here |
' adooooo x 000000 00000--------------------]
'
'hope this comes out -- spaces tend to get dropped -- align the 'x's
you already seem to have your artwork done
I was figuring on adding the 2nd ard- but not dedicate the pins -- we have a lot more IO avail
I find it hard to put ribbon cable headers on that large of a matrix [15x8]

basicchip
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Re: accurate timing

Postby basicchip » Wed Jul 09, 2014 10:00 pm

I guess you are trying to put 2 shields on 1 board, sounds good, but that makes the board bigger than it needs to be and many shields might end up interfering with each other anyway.

With the 5x18 array, that lines up with cheap vector board or is a real easy layout custom stuff for. There never is such a thing as one size fits all, that is why there are 100s of different ARMs out there.

This fills the need between the huge Keil boards that bring all the pins out, and the XPresso boards that only bring a few out.


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