FPGA memory capability

[lightmiddle]

   I have another question about FPGA memory.I am using PXI 7833R card and Labview 7.1 with windows XP.

   The PXI 7833 R has 190k memory on board. I am using memory extension utilitiy to generate memory blocks.

    I  generated a U32 16K memory block.

     Now my quesiton is that the 16k memory block is decribed like this: 32x4096.vi , the valid address is 0~4096. I am confused about the definition of the 16k memory block. If the valid address is only 4096, how do they get the 16k out of the memory block?

      Previously I was thinking that 16K U32 memory block can save 16000 U32 numbers. But now it seems I can only save 4096 U32 numbers. Then for the 190K memory How many numbers I can save in it maxumly?

Thanks.

[Christian_L]

16k refers to the total size of memory (16 kiloByte) in the memory block. Because each U32 element takes up 4 bytes, you effectively can store 4096 U32 elements. If you want to store 16000 U32s, you should allocate a 64 kB memory block.

The 192 kB of memory on the 7833 allow you to store a total of ~48000 U32 elements.

[Helmut_K]

I have some questions which refer to this topic:

1. Is it ture that the memory extention utility generate maximal 64k memory blocks?

2. Are there some possibilties to extend memory blocks?

3. How much flash memory has the PXI 7813R on board?

PS: I am using PXI 7813R card and Labview 7.1 with windows XP.

[Ame_G]

Helumt_K,

Here are the answers to the questions you have posted.
1. Using the memory extension utility you can 128 byte to 80K bytes of blocks of memory. You can find the list of memory blocks that is possible to create once you have installed the memory extension utility.
2. It is not possible to increasing the memory size. The flash card is available to store startup VI and some attributes like calibration constants. The flash card memory is not available to store data or as an extension of RAM memory.
Please refer to the link below for more information about the memory extension utility.
http://zone.ni.com/devzone/conceptd.nsf/webmain/5e9898aa65ea24e6862570c0006d4561

Regards,
Ame G.
National Instruments

[Helmut_K]

Ame G,

first of all, thank you for your answer. Also the posted link was helpful.

But I have one more question to a special problem in my application.

In that case I used the PXI NI-7811R with LabVIEW 7.1 and the FPGA Module 1.1. When I generated 2x 32K memory blocks with the memory extention utility tool it worked fine. But when I implemented 4x 32K blocks in my FPGA code I wasn't able to compile.

The PXI NI7811R has 81920 bytes embedded RAM available (datasheet --> NI7811R). I guess this factor limits adressable memory space. Is it correct?

For exemple, the NI 7813R with 180K embedded RAM available will work with 4x 32K memory blocks ??

PS: I need this information to dimension memory allocation and NI products.

Best regards,

Helmut

[Christian_L]

Correct Helmut,

The embedded RAM is the memory used by the memory blocks. The 7811R and 7813R have 80 kB of memory available, while the 7813R and 7833R have 192 kB of memory.

Allocating 2x32k memory blocks takes up 64 kB of memory, while four of those blocks would require 128 kB of memory which are not available on the smaller cards, but are available on the larger cards.

Please be aware that other functions in your LV FPGA diagram may also use some of the memory on the card. These functions include Memory Read and Memory Write, FIFOs, Look-up Tables and the Sine Generator. All of these functions and the memory blocks share the same memory available.