Hi, I have a question concerning the write operation for a DDR SDRAM with a burst length of 1: If you have a look at http://mitglied.lycos.de/vazquez78 you can see the sequence of eight back-to-back write requests that go to two different rows in the DDR SDRAM device. In the shown instance (DDR SDRAM Controller MegaCore User Guide Altera) the burst length is one on the Controller Local Interface and two on the Memory Side. My question: Why do the addresses on the local interface "local_col_addr" "020","021","022","023","030","031","032","033" turn to the memory addresses "0040","0042","0044","0046","0060","0062","0064","0066" on the DDR SDRAM Interface ? It is said later in the User Guide that the controller runs the DQ port to the DDR devices at one half the width and twice the rate of the DATAIN port (input data at the local interface of the controller). But how are the coherence with the shown example addresses? Thank you in advance. Rgds Andr�
DDR SDRAM
Started by ●August 24, 2004
Reply by ●August 24, 20042004-08-24
ALuPin@web.de (ALuPin) writes:> My question: > Why do the addresses on the local interface "local_col_addr" > "020","021","022","023","030","031","032","033" > turn to the memory addresses > "0040","0042","0044","0046","0060","0062","0064","0066" on the DDR > SDRAM Interface ? > > It is said later in the User Guide that the controller runs the DQ > port to the DDR devices at one half the width and twice the rate of > the DATAIN port (input data at the local interface of the > controller). > > But how are the coherence with the shown example addresses?Because the internal interface has a data width of sixteen bit while the the SDRAM interface is only eight bits wide... --Marcus
Reply by ●August 25, 20042004-08-25
Marcus Harnisch <marcus.harnisch@gmx.net> wrote in message news:<86k6vow8nx.fsf@dipsy.harnisch.local>...> ALuPin@web.de (ALuPin) writes: > > My question: > > Why do the addresses on the local interface "local_col_addr" > > "020","021","022","023","030","031","032","033" > > turn to the memory addresses > > "0040","0042","0044","0046","0060","0062","0064","0066" on the DDR > > SDRAM Interface ? > > > > It is said later in the User Guide that the controller runs the DQ > > port to the DDR devices at one half the width and twice the rate of > > the DATAIN port (input data at the local interface of the > > controller). > > > > But how are the coherence with the shown example addresses? > > Because the internal interface has a data width of sixteen bit while > the the SDRAM interface is only eight bits wide... > > --MarcusBut if it is 8bit wide why is 020 used and not 20 ? And what about that DQ port to the DDR device is one half the width ? Rgds Andre
Reply by ●August 26, 20042004-08-26
Hi Andre, Don't get me wrong, but if you are trying to decypher the waves at the SDRAM interface it would help if you'd know about some of the basics of DDR SDRAMs. The "usual suspects" (Micron, Samsung, etc.) provide good datasheets for download. JEDEC79x (x >= C) might be a little dry but is certainly the most comprehensive source of information in that respect. Good luck, Marcus
Reply by ●August 27, 20042004-08-27
Marcus Harnisch <marcus.harnisch@gmx.net> wrote in message news:<86fz69bmmg.fsf@dipsy.harnisch.local>...> Hi Andre, > > Don't get me wrong, but if you are trying to decypher the waves at the > SDRAM interface it would help if you'd know about some of the basics > of DDR SDRAMs. The "usual suspects" (Micron, Samsung, etc.) provide > good datasheets for download. JEDEC79x (x >= C) might be a little > dry but is certainly the most comprehensive source of information in > that respect. > > Good luck, > MarcusHi Marcus, could you tell me where to find that JEDEC79x ? Thank you Andr�
Reply by ●August 27, 20042004-08-27
Reply by ●September 3, 20042004-09-03
Marcus Harnisch wrote:> Hi Andre, > > Don't get me wrong, but if you are trying to decypher the waves at the > SDRAM interface it would help if you'd know about some of the basics > of DDR SDRAMs. The "usual suspects" (Micron, Samsung, etc.) provide > good datasheets for download. JEDEC79x (x >= C) might be a little > dry but is certainly the most comprehensive source of information in > that respect. >I personally find the Micron data sheets to be very good references, myself. -hpa