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Valued Contributor III
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TimeQuest asynchronous path

Hi all. 

 

I'm trying to interface a cyclone II device to an (asynchronous) SRAM (DE2 board). I have a written memory controller, and for a read operation I wait for several clock cycles (25Mhz) with the address registered and ce/we/oe  

with the proper values - and after a fixed period of time has passed - I sample the SRAM output data inside the FPGA. 

 

a second feature I have is registering the address and at next clock edge - registering the SRAM data outputs (asynchronous path: FPGA address reg --> SRAM address inputs --> SRAM data outputs --> FPGA data inputs). 

 

I would like to constrain the path with the TimeQuest by setting the input / output delay. what I had in mind is setting the output delay to: 

 

outputdelay_max=board_delay+SRAM_read_delay+Tsu (FPGA clock setup, 

 

since the sampling clock is the FPGA's clock itself). 

 

am I wrong? should I try a different approach? and can I use the latter 

 

and not introduce an input delay? 

 

Thanks in advance, 

 

Eyal.
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