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1answer
29 views

DDR2 data rate and data bus confusion

I am reading on DDR2 memory from past few days and have got confused with some of the terms involved. I am mainly confused from discrete memory (single DDR2 memory IC) rather than DIMM module which ...
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0answers
38 views

DDR2 memory interface and requirement of termination voltage VTT

I am currently designing a board with Freescale's K series microcontroller and a DDR2 SDRAM memory chip. The interface is point-to-point with only one DDR2 memory interfacing to the microcontroller. ...
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1answer
61 views

First DDR2 Layout - How much of a data lane must have the same reference?

Doing my first DDR2 layout and I'm hitting some conflicting requirements. I have dogbones to an internal ground-referenced layer, and then short top layer traces at the other end going from the ...
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2answers
94 views

Series Termination DDR

I was Going through some application notes for the placement of Series termination of DDR and found it should be placed near to the processor. But if I am not wrong termination resistor are placed to ...
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0answers
228 views

Why All DDR's (DDR, DDR2, DDR3) internal clock sets to 200MHz

If we see the DDR Upgrade technology explain below the internal clock of all DDR is set to 200 MHz. DDR For example,DDR-400 Efficient frequency data bus is 400 MHz True clock rate (IO buffer ...
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0answers
212 views

Can I use full-size 64/72 bit DDR2/DDR3 memory module with CycloneV hardware controller of 24 + 24 bits?

I thinking of using Cyclone V FPGA and its hardware memory controller: There is "Cyclone V FPGA Multiport Memory Controller" document from Altera: ...
2
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1answer
47 views

DDR2 memory addressing error

I have a Freescale MPC8640-based board with 4 Micron DDR2 chips of 128Mx16 density (total of 1GB) attached to it. The memory has been mapped to address range from 0x0000_0000 to 0x3FFF_FFFF. While ...
2
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1answer
413 views

What is DDR software leveling?

What is DDR software leveling ? How it is different from DDR2 and DDR3 ? Why it is required and important ? Is there a hardware leveling ? I have found some explanation here about DDR3 and a ...
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2answers
521 views

How DDR2 SDRAM works?

I have the Xilinx Spartan-3AN Starter Kit and I need to use the on board DDR2 SDRAM (MT47H32M16CC-XX). Until now I only used Static RAM and this type of memory is new for me. Can someone explain me ...
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1answer
609 views

Is there a PCB-layout related reasoning behind DDR memory package and footprint?

BGA DDR packages have a unique footprint. There are two columns of pads on both sides of the device, and an empty column in between. Is there a reasoning behind the placement of these pads (in ...
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3answers
345 views

Single Board Computer (SBC) suggestion for interfacing with DMA

I am taking over a project where a Spartan 6 FPGA provides the interface between an ADC and a DDR2 memory chip. The FPGA takes 16-bit data out of the ADC and stores it into the RAM at a rate of 28MHz. ...
3
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1answer
234 views

Crosstalk on PCB

I am currently working on a PCB with DDR2 on it. We are bringing out the DDR2 CLK, DQS signals using pogo pins to make some timing measurements. The length of the pins are about 5 cm. The problem is ...
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2answers
176 views

Localized RAM readback errors: chip or timing issue?

I'm currently testing the hardware of a prototype board using DDR2 memory, and I get RAM readback errors when performing a memory test. The errors happen in this fashion: ...
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1answer
305 views

Will DDR2 memory work with DM pins tied to LOW, if no data masking is required?

I have a board with the LDM and UDM pins swapped. If they are tied to low, will the memory still 'work', given that data is always written to mod 4 addresses and always using all 4 bytes? Memory is ...
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2answers
462 views

DDR2-SDRAM Termination methods: passive vs. active

for a project I'm designing I am currently using a simple parallel Resistor Termination on the DDR2-Traces. But I'm wondering, what is the advantage of using a voltage regulator with ...
2
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1answer
737 views

Do I need to control trace impedance for DDR2 memory?

I am going to try to interface low-speed 8bit DDR2 chip to FPGA, and I've got some questions crucial to make it work :-) 3) What is up with controlled impedance of PCB traces? Why it's important? ...
4
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1answer
350 views

Do DDR2 chips and controllers have on-die termination?

I am going to try to interface a low-speed 8-bit DDR2 chip with an FPGA, and I've got some questions crucial to make it work: Is that correct that there is on-die termination on both DDR2 memory and ...