DSP48E1作为延迟移位寄存器

硬件是有用的！
如果通过使用（丰富的）DSP48，您可以释放一些使用频繁的切片逻辑，然后继续前进并执行此操作。
将这样一个强大的组件用于如此简单的事情可能会很疯狂，但另一种方法是让LUT和FF完成所有工作时，强大的组件绝对不做任何事情。
在原帖中查看解决方案



以下为原文

The hardware is there to be used! If by using a (plentiful) DSP48 you can free up some heavily-used slice logic, then go right ahead and do that.
 
It may be crazy to use such a powerful component for something so simple, but the alternative is to leave the powerful component doing absolutely nothing while the LUTs and FFs do all the work.
View solution in original post

硬件是有用的！
如果通过使用（丰富的）DSP48，您可以释放一些使用频繁的切片逻辑，然后继续前进并执行此操作。
将这样一个强大的组件用于如此简单的事情可能会很疯狂，但另一种方法是让LUT和FF完成所有工作时，强大的组件绝对不做任何事情。



以下为原文

The hardware is there to be used! If by using a (plentiful) DSP48 you can free up some heavily-used slice logic, then go right ahead and do that.
 
It may be crazy to use such a powerful component for something so simple, but the alternative is to leave the powerful component doing absolutely nothing while the LUTs and FFs do all the work.

什么@ u4223374说的......
- 如果提供的信息有用，请将答案标记为“接受为解决方案”。给予您认为有用且回复的帖子。



以下为原文

what @u4223374 said ...
- Please mark the Answer as "Accept as solution" if information provided is helpful.
Give Kudos to a post which you think is helpful and reply oriented.

一般来说，我同意其他答案。
使用DSP48（或块RAM）有一个可能的缺点，那就是时序。
虽然DSP48本身非常快，但它们并不像部件中的切片那么丰富。
因此，您最终可能会有更长的路由距离到达最近的DSP48，而最近的SRL（LUTM）将非常接近。
在大型设计中，这种额外的布线距离可能使得更难以满足时序要求。
如果您考虑使用DSP48保存切片，我假设您的设备已满。
如果没有，那么未使用的DSP与未使用的LUT没有什么特别之处，因此使用DSP单元没有太大的优势。
-  Gabor



以下为原文

Generally I agree with the other answers.  There is one possible down side to using DSP48 (or block RAM for that matter) and that is timing.  While the DSP48 itself is quite fast, they are not as abundant as slices in the part.  Therefore it is possible that you will end up with some longer routing distances to reach the nearest DSP48 while the nearest SRL (LUTM) would be quite close.  In a large design this extra routing distance could make it harder to meet timing.  I assume that your device is getting full if you consider using DSP48 to save slices.  If not, then there's nothing special about unused DSP's vs unused LUT's so there's no great advantage to using the DSP units.
-- Gabor

感谢所有的回复 - 时间影响很有意思。
我做了一些测试，最终选择了一个可配置的解决方案，所以我可以选择带有参数的DSP，SRL或基于FF的延迟，因为（目前）我不受空间限制，但我真的不认为我'
我将把DSP用于其他任何事情......但我还不确定，因为我还有很多工作要做。
我必须说使用DSP进行延迟具有许多优点，通过一些巧妙地使用级联输入和输出（以及一些限制），您可以获得每个DSP在1个周期和4个周期之间的延迟的良好时序，以及
使用它们作为输入多路复用器，因此可以节省相当多的LUT。
例如，我使用2个DSP作为2路32位输入多路复用器，具有5个周期的延迟......无需其他逻辑。
李。



以下为原文

Thanks for all the replies -- the timing implications are interesting.
 
I've done some testing and have ultimately gone for a configurable solution so I can choose either DSP, SRL or FF based delays with a parameter, as (at the moment) I'm not space constrained, but I really don't think I'll be using the DSPs for anything else .. but I don't know for sure yet as I still have a lot to do.
 
I must say that using the DSPs for delays has a number of advantages, with some clever use of the cascade inputs and outputs (and with some restrictions) you can get good timing on delays between 1 cycle and 4 cycles for each DSP, and also use them as an input mux so there can be quite a LUT saving.
 
For example I'm using 2 DSPs as a 2-way 32 bit input multiplexer with a 5 cycle delay ... with no other logic needed.
 
Lee.