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Discussion Groups | AT91SAM ARM | timing calculation
For users of the Atmel AT91SAM7 and AT91SAM9 ARM CPU chips. Atmel has taken a new direction by combining on chip flash and ram with the ARM CPU on a single die. This provides low cost devices for small systems using the ARM CPU. This group is to exchange information to help users get started and learn how to use the devices.
timing calculation - Bernd - Aug 6 15:52:09 2008
Hi,
I`ve a question about timing. The trace difference is 40mm, the
frequency is 96MHz and the FR4-material-speed is approximately 0.16
m/ns.
How do I`ve to calculate the time which the signal needs for this
distance? Is it just simple t = s / v = 0.044m / 0.16m/ns = 0.24ns?
best regards
Bernd
------------------------------------
(You need to be a member of AT91SAM -- send a blank email to AT91SAM-subscribe@yahoogroups.com )
I`ve a question about timing. The trace difference is 40mm, the
frequency is 96MHz and the FR4-material-speed is approximately 0.16
m/ns.
How do I`ve to calculate the time which the signal needs for this
distance? Is it just simple t = s / v = 0.044m / 0.16m/ns = 0.24ns?
best regards
Bernd
------------------------------------
(You need to be a member of AT91SAM -- send a blank email to AT91SAM-subscribe@yahoogroups.com )
Re: timing calculation - Charles Manning - Aug 6 19:06:18 2008
On Thursday 07 August 2008 07:52:00 Bernd wrote:
> Hi,
>
> I`ve a question about timing. The trace difference is 40mm, the
> frequency is 96MHz and the FR4-material-speed is approximately 0.16
> m/ns.
>
> How do I`ve to calculate the time which the signal needs for this
> distance? Is it just simple t = s / v = 0.044m / 0.16m/ns = 0.24ns?
>
There's more to getting a signal through than just the propagation. You also
need to consider the time needed to charge the input stage of the device
you're driving.
-- CHarles
------------------------------------
(You need to be a member of AT91SAM -- send a blank email to AT91SAM-subscribe@yahoogroups.com )
> Hi,
>
> I`ve a question about timing. The trace difference is 40mm, the
> frequency is 96MHz and the FR4-material-speed is approximately 0.16
> m/ns.
>
> How do I`ve to calculate the time which the signal needs for this
> distance? Is it just simple t = s / v = 0.044m / 0.16m/ns = 0.24ns?
>
There's more to getting a signal through than just the propagation. You also
need to consider the time needed to charge the input stage of the device
you're driving.
-- CHarles
------------------------------------
(You need to be a member of AT91SAM -- send a blank email to AT91SAM-subscribe@yahoogroups.com )
Re: timing calculation - bernd schuster - Aug 7 1:07:05 2008
2008/8/7 Charles Manning
> On Thursday 07 August 2008 07:52:00 Bernd wrote:
> > Hi,
> >
> > I`ve a question about timing. The trace difference is 40mm, the
> > frequency is 96MHz and the FR4-material-speed is approximately 0.16
> > m/ns.
> >
> > How do I`ve to calculate the time which the signal needs for this
> > distance? Is it just simple t = s / v = 0.044m / 0.16m/ns = 0.24ns?
> > There's more to getting a signal through than just the propagation. You
> also
> need to consider the time needed to charge the input stage of the device
> you're driving.
>
> -- CHarles
>
Where do I find this time in the datasheet (AT91SAM9260; for the external
memory interface SMC)?
Is it correct that the setup time is the time between NRD / NWE goes low and
the data is available (e.g. SMC33 - SMC23)? And the other device (in may
case a flash memory) must have such a long hold time to get the data???? But
the hold time is always 0ns....
best regards
Bernd
>
(You need to be a member of AT91SAM -- send a blank email to AT91SAM-subscribe@yahoogroups.com )
> On Thursday 07 August 2008 07:52:00 Bernd wrote:
> > Hi,
> >
> > I`ve a question about timing. The trace difference is 40mm, the
> > frequency is 96MHz and the FR4-material-speed is approximately 0.16
> > m/ns.
> >
> > How do I`ve to calculate the time which the signal needs for this
> > distance? Is it just simple t = s / v = 0.044m / 0.16m/ns = 0.24ns?
> > There's more to getting a signal through than just the propagation. You
> also
> need to consider the time needed to charge the input stage of the device
> you're driving.
>
> -- CHarles
>
Where do I find this time in the datasheet (AT91SAM9260; for the external
memory interface SMC)?
Is it correct that the setup time is the time between NRD / NWE goes low and
the data is available (e.g. SMC33 - SMC23)? And the other device (in may
case a flash memory) must have such a long hold time to get the data???? But
the hold time is always 0ns....
best regards
Bernd
>
(You need to be a member of AT91SAM -- send a blank email to AT91SAM-subscribe@yahoogroups.com )