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打算在FPGA 内采用DDR内存
以前从来没用过
现在开始记录自己的学习经历吧:
资料在这:
http://www.altera.com.cn/literature/hb/cyc2/cyc2_cii51009.pdf
上面写了:
You can use any of the user I/O pins for commands and addresses.
Because of the symmetrical setup and hold time for the command and
address pins at the memory device, you may need to generate these
signals from the negative edge of the system clock.
地址线可以用任意的IO。
The clocks to the SDRAM device are called CK and CK#. Use any of the
user I/O pins via the DDR registers to generate the CK and CK# signals
to meet the tDQSS requirements of the DDR SDRAM or DDR2 SDRAM
device. The memory device’s tDQSS requires the positive edge of the write
DQS signal to be within 25% of the positive edge of the DDR SDRAM and
DDR2 SDRAM clock input. Because of strict skew requirements between
CK and CK# signals, use adjacent pins to generate the clock pair.
Surround the pair with buffer pins tied to VCC and pins tied to ground for
better noise immunity from other signals.
时钟 必须从DDR 寄存器? 这是什么意思呢? |
阿莫论坛20周年了!感谢大家的支持与爱护!!
知道什么是神吗?其实神本来也是人,只不过神做了人做不到的事情 所以才成了神。 (头文字D, 杜汶泽)
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