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Simplifying an SDRAM controller design by using burst length = 1 exclusively

IP.com Disclosure Number: IPCOM000022086D
Original Publication Date: 2004-Feb-23
Included in the Prior Art Database: 2004-Feb-23
Document File: 1 page(s) / 29K

Publishing Venue

IBM

Abstract

Disclosed is a design for simplifying a Synchronous Dynamic Random Access Memory (SDRAM) controller by the exclusive use of the burst length equal to one option.

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Simplifying an SDRAM controller design by using burst length = 1 exclusively

A Synchronous Dynamic Random Access Memory (SDRAM) controller design must be
capable of bursting data to the SDRAM in order to take full advantage of the
available bandwidth. Typically this is accomplished with an integer number of
burst read commands or burst write commands (i.e. burst length greater than
one). However, if the total burst length required is not an even multiple of
the burst length command or even if the total burst length required is itself
less than the programmed burst length, then the SDRAM controller must also
issue burst stop commands and in some cases assert the data mask (DM) signal
to the SDRAM to terminate such a burst. This introduces additional
complexity into the design which can easily introduce logic defect(s) which
may elude detection until late in the design cycle. This can add delay into
the design cycle and ultimately delay the availability of the SDRAM
controller.

This design approach solves this problem by executing all SDRAM read and write
commands with the burst length equal to one option. Thus, by definition there
is no required burst length that is not a multiple of the programmed SDRAM
burst length. Therefore the burst stop command is never required to be issued
nor is the data mask (DM) required to be asserted. This design does require
that a SDRAM read or a SDRAM write command be transmitted during every cycle
that data is to be transferred to/from the SDRAM. These commands require an
address be sent with each command. However, the SDRAM command bus is an
under-utilized bus and thus is available for this purpose. It is actually
simpler for the har...