Dear all,

This may sound stupid to ask, but I am very frustrating now as my
deadline is approaching.  I want to make use of the VGA generator
example on www.xess.com.  How could I write/read data to the specific
address of the SRAM?
I would have to have a SRAM controller that writes and reads data to
the SRAM?  How should that be implemented in VHDL?  What else do I
need?  I am planning to hard code the data to SRAM.  Thank you very
much!!!

you can download xilinx sdram controller here-
ftp://ftp.xilinx.com/pub/applications/xapp/xapp134_vhdl.zip
and tune it to your requirement.

Neo wrote:
> you can download xilinx sdram controller here-
> ftp://ftp.xilinx.com/pub/applications/xapp/xapp134_vhdl.zip
> and tune it to your requirement.

Well, it would take a lot of tuning to access SRAM with an SDRAM 
controller. ;-)

Kolja Sulimma

"greenplanet"
<g...@hotmail.com> wrote in 
news:1...@l41g2000cwc.googlegroups.com:

> Dear all,
> 
> This may sound stupid to ask, but I am very frustrating now as my
> deadline is approaching.  I want to make use of the VGA generator
> example on www.xess.com.  How could I write/read data to the specific
> address of the SRAM?
> I would have to have a SRAM controller that writes and reads data to
> the SRAM?  How should that be implemented in VHDL?  What else do I
> need?  I am planning to hard code the data to SRAM.  Thank you very
> much!!!

I assume you are actually referring to the SDRAM on the XSA Board and not 
the internal block SRAMs of the FPGA.  The VGA generator design files 
archive (http://www.xess.com/projects/an-101204-vgagen.zip) already 
includes an example where the VGA generator is connected to the XESS 
SDRAM controller  so it can display images stored in the SDRAM.  You can 
use the GXSLOAD utility to download images to the SDRAM.  And you can use 
the img2xes utility (http://www.xess.com/downloads/img2xes.zip) to 
convert commonly-used image files into a format that GXSLOAD can handle.




-- 
----------------------------------------------------------------
Dave Van den Bout
XESS Corp.
PO Box 33091
Raleigh NC 27636
Phn: (919) 363-4695
Fax: (801) 749-6501
d...@xess.com
http://www.xess.com

Thanks for the replies.

What I meant is the SRAM on the XS40 board, so the vga generator
example for XS40 works the same way as the one for XSA board?  The
img2xes utility works for XS40 too?
What if I actually have a bunch of data (put them all together would
make an image I suppose), how should I store the data to the SRAM?  I
would also have to modify the vga generator example since it always
sets web = '1'?

"greenplanet"
<g...@hotmail.com> wrote in 
news:1...@f14g2000cwb.googlegroups.com:

> Thanks for the replies.
> 
> What I meant is the SRAM on the XS40 board, so the vga generator
> example for XS40 works the same way as the one for XSA board?

No, the XSA VGA generator fetches image data from 16-bit SDRAM so it has 
to account for the variable arrival time of the data with a FIFO.  The 
XS40 has a static 8-bit RAM with a fixed access time so the FIFO isn't 
needed and the image path is narrower.

  The
> img2xes utility works for XS40 too?

img2xes just translates the format of common image files into the simple 
XES format.  The XES file can be downloaded into the XS40 SRAM using the 
GXSLOAD utility.  You should be able to use the img2xes options to format 
the image data for the byte-wide SRAM on the XS40.  

> What if I actually have a bunch of data (put them all together would
> make an image I suppose), how should I store the data to the SRAM?  I
> would also have to modify the vga generator example since it always
> sets web = '1'?

For writing to the SRAM:

1) Lower the RAM chip-enable and raise the output-enable.
2) Output the address and data.
3) Pulse the write-enable low and then high.

You will have to modify the VGA generator to make it release the RAM 
address, data and control pins while you do the write operations.
 


-- 
----------------------------------------------------------------
Dave Van den Bout
XESS Corp.
PO Box 33091
Raleigh NC 27636
Phn: (919) 363-4695
Fax: (801) 749-6501
d...@xess.com
http://www.xess.com

>Dear all,
>
>This may sound stupid to ask, but I am very frustrating now as my
>deadline is approaching.  I want to make use of the VGA generator
>example on www.xess.com.  How could I write/read data to the specific
>address of the SRAM?
>I would have to have a SRAM controller that writes and reads data to
>the SRAM?  How should that be implemented in VHDL?  What else do I
>need?  I am planning to hard code the data to SRAM.  Thank you very
>much!!!
>

HI, I just also do the same work. I have the same problem. And have youresolve the problem? I would like to discuss it with you! Hier is my emailaddress: q...@hotmail.com.

"qtommy"
<q...@hotmail.com> schrieb im Newsbeitrag 
news:O...@giganews.com...
> >Dear all,
>>
>>This may sound stupid to ask, but I am very frustrating now as my
>>deadline is approaching.  I want to make use of the VGA generator
>>example on www.xess.com.  How could I write/read data to the specific
>>address of the SRAM?
>>I would have to have a SRAM controller that writes and reads data to
>>the SRAM?  How should that be implemented in VHDL?  What else do I
>>need?  I am planning to hard code the data to SRAM.  Thank you very
>>much!!!
>>
>
> HI, I just also do the same work. I have the same problem. And have you
> resolve the problem? I would like to discuss it with you! Hier is my email
> address: q...@hotmail.com.
>
>

The xess demo only reads from the SDRAM, for write access you need to make 
some statemachine based arbiter that will allow write access the SDRAM, 
there is no demo for that unfortunatly, I did a quick dirty thing once it 
only wrote a small image from camera in the SDRAM

-- 
Antti Lukats
http://www.xilant.com

Antti Lukats wrote:
> "qtommy" <q...@hotmail.com> schrieb im Newsbeitrag
> news:O...@giganews.com...
> > >Dear all,
> >>
> >>This may sound stupid to ask, but I am very frustrating now as my
> >>deadline is approaching.  I want to make use of the VGA generator
> >>example on www.xess.com.  How could I write/read data to the specific
> >>address of the SRAM?
> >>I would have to have a SRAM controller that writes and reads data to
> >>the SRAM?  How should that be implemented in VHDL?  What else do I
> >>need?  I am planning to hard code the data to SRAM.  Thank you very
> >>much!!!
> >>
> >
> > HI, I just also do the same work. I have the same problem. And have you
> > resolve the problem? I would like to discuss it with you! Hier is my email
> > address: q...@hotmail.com.
> >
> >
>
> The xess demo only reads from the SDRAM, for write access you need to make
> some statemachine based arbiter that will allow write access the SDRAM,
> there is no demo for that unfortunatly, I did a quick dirty thing once it
> only wrote a small image from camera in the SDRAM

Actually, this is no longer true.  We have a new VGA generator
application that allows the image data to be updated in the SDRAM while
the VGA generator is operating
(http://www.xess.com/appnotes/an-103005-vgagen.html).  This is done
using a dual-port module that fits onto our SDRAM controller and allows
you to have multiple, independent channels in and out of the external
SDRAM.

> 
> -- 
> Antti Lukats
> http://www.xilant.com

<d...@xess.com> schrieb im Newsbeitrag 
news:1...@o13g2000cwo.googlegroups.com...
>
> Antti Lukats wrote:
>> "qtommy" <q...@hotmail.com> schrieb im Newsbeitrag
>> news:O...@giganews.com...
>> > >Dear all,
>> >>
>> >>This may sound stupid to ask, but I am very frustrating now as my
>> >>deadline is approaching.  I want to make use of the VGA generator
>> >>example on www.xess.com.  How could I write/read data to the specific
>> >>address of the SRAM?
>> >>I would have to have a SRAM controller that writes and reads data to
>> >>the SRAM?  How should that be implemented in VHDL?  What else do I
>> >>need?  I am planning to hard code the data to SRAM.  Thank you very
>> >>much!!!
>> >>
>> >
>> > HI, I just also do the same work. I have the same problem. And have you
>> > resolve the problem? I would like to discuss it with you! Hier is my 
>> > email
>> > address: q...@hotmail.com.
>> >
>> >
>>
>> The xess demo only reads from the SDRAM, for write access you need to 
>> make
>> some statemachine based arbiter that will allow write access the SDRAM,
>> there is no demo for that unfortunatly, I did a quick dirty thing once it
>> only wrote a small image from camera in the SDRAM
>
> Actually, this is no longer true.  We have a new VGA generator
> application that allows the image data to be updated in the SDRAM while
> the VGA generator is operating
> (http://www.xess.com/appnotes/an-103005-vgagen.html).  This is done
> using a dual-port module that fits onto our SDRAM controller and allows
> you to have multiple, independent channels in and out of the external
> SDRAM.
>

sorry, I did not know - it does pay off to look at XESS website from
time to time to get new stuff!!

independant channel support is really nice thing to have

>> Antti Lukats
>> http://www.xilant.com
>