Nios® II Embedded Design Suite (EDS)
Support for Embedded Development Tools, Processors (SoCs and Nios® II processor), Embedded Development Suites (EDSs), Boot and Configuration, Operating Systems, C and C++
Announcements
Intel Support hours are Monday-Fridays, 8am-5pm PST, except Holidays. Thanks to our community members who provide support during our down time or before we get to your questions. We appreciate you!

Need Forum Guidance? Click here
Search our FPGA Knowledge Articles here.
12435 Discussions

Nios running on SRAM vs DDR2 ?

Altera_Forum
Honored Contributor II
811 Views

Hi, 

 

To gain space I am thinking about replacing tqfp SRAM (cy7c1380) with bga DDR2. 

Is there any difference between using a nios on sram or on ddr ? what are the problems with ddr ? 

 

thanks.
0 Kudos
3 Replies
Altera_Forum
Honored Contributor II
93 Views

If the problem is only pcb space, I think cy7c1380, too, is available in a bga package. 

Anyway, ddr2 like any dram memory have a much lower cost per bit compared to sram, so it could be convenient for saving $$ besides saving space, especially if you need a big memory. 

The major problem with DDR2 is designing pcb. Unlike sram, ddr2 devices don't use LVTTL signaling but SSTL 18. This signaling standard requires impedance matching and a careful design of traces in order to avoid transmission problems.  

Apart this point, DDR2 then works much like an usual sdram, so all pro-con comparisions between sram and dram apply.
Altera_Forum
Honored Contributor II
93 Views

thanks for your response !

Altera_Forum
Honored Contributor II
93 Views

The read/write cycle times will also be somewhat different. 

This may not make much difference for cache line read/write, but for random cycles the DDR2 is likely to be slower.
Reply