xilinx xc9536?

Hello, there are some pins on xilinx xc9536 which are called global
clock1/2/3
global reset, etc, where are these explained?

On 2006-12-31, <highZ> <> wrote:
> Hello, there are some pins on xilinx xc9536 which are called global
> clock1/2/3
> global reset, etc, where are these explained?

There's a document called something like "XC9500 device family datasheet".
Those pins are (optionally) connected to special internal routing resources
that make them suitable for use as input clocks and global set/reset.
Isn't there also a global tristate?

-- 
Ben Jackson AD7GD
<ben@ben.com>
http://www.ben.com/

Look at
http://direct.xilinx.com/bvdocs/publications/ds064.pdf
pin-outs on page 6
Peter Alfke

On Dec 31, 10:18 am, <highZ> wrote:
> Hello, there are some pins on xilinx xc9536 which are called global
> clock1/2/3
> global reset, etc, where are these explained?

> Look at
> http://direct.xilinx.com/bvdocs/publications/ds064.pdf
> pin-outs on page 6

This is true, page 6 shows which pins are which. But what I was
asking is different -- what is the reason for these pins, when do
we use them, what do they do?

For example, I can connect an oscillator to any IO pin, which
can then be used in statements like

always @ (posedge input-pin)


> Peter Alfke

My rule is:
Use the smallest possible number of different clock signals (one is
best) and use the tight global clock distribution to avoid hold-time
issues altogether, and also to achieve highest performance.
And, last not least, simplify the debugging process.
The problems you will encounter and the time to resolve them, are both
proportional to the number of different clocks you are using. But maybe
it's a third-power relationship  ;-)
Peter Alfke

On Jan 1, 1:27 pm, <highZ> wrote:
> > Look at
> >http://direct.xilinx.com/bvdocs/publications/ds064.pdf
> > pin-outs on page 6This is true, page 6 shows which pins are which. But what I was
> asking is different -- what is the reason for these pins, when do
> we use them, what do they do?
>
> For example, I can connect an oscillator to any IO pin, which
> can then be used in statements like
> 
> always @ (posedge input-pin)
> 
> > Peter Alfke

H-Z,

Dedicated pins are used to offer some benefit that would not be 
available from a general purpose pin.  For example, a clock should have 
less delay than any other signal, or else you would need to worry that 
the clock might arrive after the data.  Thus dedicated clock pins have 
lower skew than other pins.  By using the dedicated clocks, the internal 
routing is never an issue.  If you used some other general purpose 
resource for a clock, then setup and hold times must be met everywhere 
that signal might go and get used.

A reset pin might have additional logic on it, to prevent glitching if a 
clock occurs simultaneous with the reset.

It is all in the data sheets, and user's guides:  really.

Austin

> Dedicated pins are used to offer some benefit that would not be
> available from a general purpose pin.  For example, a clock should have
> less delay than any other signal, or else you would need to worry that
> the clock might arrive after the data.  Thus dedicated clock pins have
> lower skew than other pins.  By using the dedicated clocks, the internal
> routing is never an issue.  If you used some other general purpose
> resource for a clock, then setup and hold times must be met everywhere
> that signal might go and get used.
>
> A reset pin might have additional logic on it, to prevent glitching if a
> clock occurs simultaneous with the reset.
>
> It is all in the data sheets, and user's guides:  really.

Which one, there are many datasheets for the 9500 familiy and
for each specific one. I had a glance at all of them and couldn't
see all these things. What exactly does 'reset' do in the first
place, well I will see again if I can find it. Thanks

>
> Austin

On 2007-01-02, <highZ> <> wrote:
>> It is all in the data sheets, and user's guides:  really.
>
> Which one, there are many datasheets for the 9500 familiy and
> for each specific one. I had a glance at all of them and couldn't
> see all these things. What exactly does 'reset' do in the first
> place, well I will see again if I can find it. Thanks

If you're really so unwilling to read the datasheets, you are doomed.

-- 
Ben Jackson AD7GD
<ben@ben.com>
http://www.ben.com/

highZ wrote:
> > Dedicated pins are used to offer some benefit that would not be
> > available from a general purpose pin.  For example, a clock should have
> > less delay than any other signal, or else you would need to worry that
> > the clock might arrive after the data.  Thus dedicated clock pins have
> > lower skew than other pins.  By using the dedicated clocks, the internal
> > routing is never an issue.  If you used some other general purpose
> > resource for a clock, then setup and hold times must be met everywhere
> > that signal might go and get used.
> >
> > A reset pin might have additional logic on it, to prevent glitching if a
> > clock occurs simultaneous with the reset.
> >
> > It is all in the data sheets, and user's guides:  really.


>
> Which one, there are many datasheets for the 9500 familiy and
> for each specific one. I had a glance at all of them and couldn't
> see all these things. What exactly does 'reset' do in the first
> place, well I will see again if I can find it. Thanks

I probably spend up to 1/2 my working life (and some of my supposedly
non-working life) , perhaps more, reading datasheets to understand and
effectively use devices.

For this particular part and issue (I use the XC9536XL in 3 designs and
I avail myself of the GCLKs for various reasons) all is indeed
explained in the following places:

1. The family datasheet (XC9500 series) has the overview and timings,
which can vary with package.

2. The device datasheet (XC9536)

3. The various application notes available on the Xilinx site.

If you wish to do this stuff successfully, you have to be willing to
absorb an inordinate amount of data from datasheets.

If you don't wish to do the work of looking, reading and
*understanding*, then our help would be futile anyway.

Cheers

PeteS

> 
> >
> > Austin

As I said, I did look, but coudn't find

> If you don't wish to do the work of looking, reading and
> *understanding*, then our help would be futile anyway.
>
> Cheers
>
> PeteS