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FPGA内部dcm输出的100MHZ时钟输出到dsp368的一个时钟引脚上,为什么会出错呢?怎眼才能解决?ERROR:Place:1136-Thisdesigncontainsaglobalbufferinstance,,drivingthenet,,thatisdrivingthefollowing(first30)non-clocklo
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FPGA内部dcm输出的100MHZ时钟输出到dsp368的一个时钟引脚上,为什么会出错呢?怎眼才能解决?
ERROR:Place:1136 - This design contains a global buffer instance,
,driving the net,,that is driving the
following (first 30) non-clock load pins.
< PIN:i_VPORT/clock_o.D; >
This is not a recommended design practice in Spartan-6 due to limitations in
the global routing that may cause excessive delay,skew or unroutable
situations.It is recommended to only use a BUFG resource to drive clock
loads.If you wish to override this recommendation,you may use the
CLOCK_DEDICATED_ROUTE constraint (given below) in the .ucf file to demote
this message to a WARNING and allow your design to continue.
< PIN "dcm_u/clkout1_buf.O" CLOCK_DEDICATED_ROUTE = FALSE; >
我按照这个提示在UCF中增加了这个约束后,虽然不报错了,但是测量时钟引脚的频率不对.怎么做约束才能让这个引脚从FPGA输出100Mhz的时钟信号?
ERROR:Place:1136 - This design contains a global buffer instance,
,driving the net,,that is driving the
following (first 30) non-clock load pins.
< PIN:i_VPORT/clock_o.D; >
This is not a recommended design practice in Spartan-6 due to limitations in
the global routing that may cause excessive delay,skew or unroutable
situations.It is recommended to only use a BUFG resource to drive clock
loads.If you wish to override this recommendation,you may use the
CLOCK_DEDICATED_ROUTE constraint (given below) in the .ucf file to demote
this message to a WARNING and allow your design to continue.
< PIN "dcm_u/clkout1_buf.O" CLOCK_DEDICATED_ROUTE = FALSE; >
我按照这个提示在UCF中增加了这个约束后,虽然不报错了,但是测量时钟引脚的频率不对.怎么做约束才能让这个引脚从FPGA输出100Mhz的时钟信号?
▼优质解答
答案和解析
加了这个约束只是不报这个问题,但并没有解决.你将时钟输出的pin映射到clk管脚输出吧,FPGA中有专门的时钟输出输入管脚,这些和内部时钟网络相连接,具有较小的skew和delay.
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