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Registered: ‎02-14-2018

Issue in Reference Design for XAPP1280 ,XAPP1282

Hi , 

 

The reference design zips  for Xapp1280 , Xapp1282 both are  having a "design_1_wrapper .vhd".

 

Both design have STARTUPE3 primitive .

 

 connection mapping for  "PACK" and "PREQ"   :

 

 PREQ      => open,               -- 1-bit output: PROGRAM request to fabric output

 PACK      => PACK_int,        -- 1-bit input: PROGRAM acknowledge input

 

The "PACK_int" is being driven by the  "PACK_int  <= pipe_signal(7); ".

 

The   pipe_signal(7) is  a final stage of 8-stages pipeline.  The  first stage of pipe-line "pipe_signal(0)" is loaded "1" when "PREQ_int = 1" .

 

The issue  is  "PREQ_int" is floating  in the ""design_1_wrapper .vhd" .  If the floating value is "1" then  everything is OK  ,as the purpose here is to  acknowledge the  STARTUPE3  that the program has been loaded.

If it is "0" then the synthesizer will optimized the whole pipeline and " PACK_int  w'd stuck at "0". 

 

My Question is " what will be the after-effect  , when the  "PACK" port of STARTUPE3 primitive stuck at "0" ? 

 

 

I guess the ""PREQ_int" should be mapped to "PREQ" of STARTUPE3 Primitive .

 

Correct Port Mapping of STARTUPE3 Primitive : 

 

 PREQ      => PREQ_int ,      -- 1-bit output: PROGRAM request to fabric output

 PACK      => PACK_int,        -- 1-bit input: PROGRAM acknowledge input

 

so that  pipe_signal(0) <= PREQ_int ;

             pipe_signal(1)  <=   pipe_signal(0)  ;

            pipe_signal(2)  <=   pipe_signa(1)  ;

              ----                          -----

             pipe_signal(7)  <=   pipe_signa(6)  ;

             PACK_int  <=   pipe_signal(7)  ;

 

-----------------

Please comment on the issue.

 

              .

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Xilinx Employee
Xilinx Employee
813 Views
Registered: ‎08-10-2008

I take a look at xapp1282 and see it intends to ground PACK pin (figure 24 of xapp1282).  Here it only wants to control the flash related ports. If PACK is grounded you will not trigger a PROGRAM event. 

The connection depends on what operations you plan to do, you can change the design files according to the needs of course.

 

-Ivy

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