We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

Showing results for 
Search instead for 
Did you mean: 
Observer karvi_in
Registered: ‎11-14-2009

mb_plb clock frequency limited to 90MHz and FPGA stepping selection issue EDK11.1





I am using a Digilent Nexys 2 board with a Spartan 3E, stepping 1 and speed grade -4 . The board comes with 50MHz oscillator and I bought a 100MHz external oscillator for the board. The datasheet states max DLL frequency of 240MHz for stepping 1 and 90MHz for stepping 0. I am using EDK 11.1


I changed the pin and values in the UCF file and the reference value in the clock generator.  However, it does not give me the option to change the Microblaze frequency. The only option is 50MHz. 


So I configured the MHS file and made 2 outputs from the clock generator 50MHz and 100MHz. But whenever, I change all the MB and bus (including mb_plb) frequencies to 100MHz,  I get the following error



PLB bus frequency <100.000000> MHz is out of range. The frequency should be in the range of <25.000000> and <90.000000> MHz.ERROR:EDK -


 I also tried creating a new project with and without the board support package from digilent. In both cases, when using the custom board specifications, I am unable to select a MB frequency greater than 88MHz (I set reference freq = 100MHz)  and the "Use stepping" pull down list is empty. 



 Is this a problem with the EDK where it does not let me select the stepping option for this particular device? Since stepping 1 is for devices manufactured after 2006, hasnt the EDK been updated accordingly?





Kind Regards,




0 Kudos
1 Reply
Registered: ‎08-21-2008

Re: mb_plb clock frequency limited to 90MHz and FPGA stepping selection issue EDK11.1


If there is nothing in the drop down menu for stepping then that device does not have any stepping i suppose. 

Best of luck.
Unlimited in my Limits.
0 Kudos