06-21-2012 05:25 PM
I am using an XC6SLX45 Spartan 6 device with ISE v13.4. I am trying to use 2 block RAMs on the FPGA, created with Block Memory Generator v6.3 in Core Generator v13.4. Implementation fails because I am using too many RAMB16BWER primitives. Excerpt from the map report:
Specific Feature Utilization:
Number of RAMB16BWERs: 175 out of 116 150% (OVERMAPPED)
Number of RAMB8BWERs: 4 out of 232 1%
Currently both BRAM cores are created using the minimal area algorithm. Is there a way to force one of the BRAMs to use the RAMB8BWER primitives? I tried to force usage of fixed primitives (16kx1, 8kx2 .... 256x36) but am not sure how those reflect to RAMB16BWER and RAMB8BWER.
06-21-2012 06:20 PM
If you have not already read UG383, you should give this a read. It is only 34 pages long, and explains the conditions in which a single native Spartan-6 18Kbit BRAM can be used as two independent 9Kbit BRAMs.
If you have not already read the New Users Forum README thread, you might find some useful information there -- including the following:
1. Read the manual or user guide. Have you read the manual? Do you know where to find the manual?
Many of the questions are answered with a simple and quick search of the FPGA family datasheet, or a related document. Of course, the first problem is locating the correct document -- there are 100s of them. For most current software and device families, Xilinx provides a software tool for finding and accessing useful documents. This tool is called DocNav, it installs on your PC, and you can download it with this .ZIP file link.
-- Bob Elkind
README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369
1. Read the manual or user guide. Have you read the manual? Can you find the manual?
2. Search the forums (and search the web) for similar topics.
3. Do not post the same question on multiple forums.
4. Do not post a new topic or question on someone else's thread, start a new thread!
5. Students: Copying code is not the same as learning to design.
6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please).
7. You are not charged extra fees for comments in your code.
8. I am not paid for forum posts. If I write a good post, then I have been good for nothing.