各位大侠
现在碰到一个问题
就是ddr2内存接续的问题
现在系统cpu是三星的32位的s3c2450(arm9核心),支持ddr,mobile ddr和ddr2
The S3C2450 Mobile DRAM Controller supports three kinds of memory interface - (Mobile) SDRAM and mobile
DDR and DDR2. Mobile DRAM controller provides 2 chip select signals (2 memory banks), these are used for up
to 2 (mobile) SDRAM banks or 2 mobile DDR banks or 2 DDR2 banks. Mobile DRAM controller can’t support 3
kinds of memory interface simultaneous, for example one bank for (mobile) SDRAM and one bank for mobile
DDR.
DDR2 Features
− Support DDR2 having 4-bank architecture, don’t support 8-bank architecture.
− Support 16-bit external data bus interface
− Support AL(Additive Latency) 0, don’t support posted CAS, it needs EMRS setting.
− Don’t support ODT and nDQS function, it needs EMRS setting.
− All other features are same to the features of SDR/mDDR
但是我看他们接续的时候
接续了两个ddr2 (32M*16),而内存上只有十六位数据线
于是他们就将两个内存芯片的数据线分为高十六位和低十六位
我的问题就是
1,要是接两个内存芯片的话必须这么接么?这么接有什么好处?
2,要是接两个芯片的话可不可以将两个芯片的数据线都接续到一起?
3,我现在是用了两个ddr2 (32M*16),但是我要是用一个ddr2 (64M*16)的话这两种方式谁更快一点,原因?
4,现在内存标称频率还有待于选择,比如说我现在可以用ddr2 667的内存,也可以用ddr2 533的内存,要是都工作在533MHz的话
ddr2 667的电磁干扰(EMI)会不会更大一点啊? |