Answers Database

M1.4 LogiBLOX: Discrepancy between Dual Port RAM Simulation and DynatextDocumentation.


Record #3265

Product Family:  Software

Product Line:  Merged Core

Problem Title:
M1.4 LogiBLOX: Discrepancy between Dual Port RAM Simulation and
DynatextDocumentation.



Problem Description:
In the LogiBLOX Reference/User Guide book in DynaText the function of the DPO pi
n on dual port RAMS is described as
follows:

DPO
The Dual Port Output is used to output the data that occurs on the Dual Port Rea
d Address input of the DP_RAM module whenever Write Enable Clock goes High.

Although this is not incorrect it is misleading.


Solution 1:

The statement in the book is true if you are writing to the
location that is currently being read, i.e., after a delay,
the value written into that location will appear on DPO.
However, in general, you usually do not write to the
same location you read from.

The value on DPO also changes depending on the value of the
address bus DPRA. When this is stable, after a delay. the data
in that part of the RAM cell appears on DPO. This allows data
to be read from the RAM independently from the write strobe.
This feature is not clear from the current documentation.



End of Record #3265