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我想知道Spartan 6 PLL输出的同相匹配程度如何。
示例:25MHz源时钟,PLL输出为150MHz和75MHz,两者都在结构中全局使用。 相位偏移设置均为“0”。 当在150MHz域中“使用”75MHz域的寄存器输出时,是否存在建立/保持时间危险? 两个时钟输出的边缘有多紧密匹配? 它们是否接近,不是那么接近,或绝对是“死坚果”? 我浏览了文档和Xilinx网站,但我找不到这些信息,包括DS162表50(PLL规范)。 DS162中有一个静态相位偏移规范,但没有特别指的是输出匹配。 谢谢你的帮助... 签名:新手的自述文件在这里:http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369总结:1。 阅读手册或用户指南。 你读过手册了吗? 你能找到手册吗?2。 搜索论坛(并搜索网页)以寻找类似的主题。 不要在多个论坛上发布相同的问题。 不要在别人的主题上发布新主题或问题,开始新的主题!5。 学生:复制代码与学习设计不同.6“它不起作用”不是一个可以回答的问题。 提供有用的详细信息(请与网页,数据表链接).7。 您的代码中的评论不需要支付额外费用。 我没有支付论坛帖子的费用。 如果我写一篇好文章,那么我一无所获。 以上来自于谷歌翻译 以下为原文 I'm wondering how well-matched, in phase, are Spartan 6 PLL outputs. Example: 25MHz source clock, PLL outputs are 150MHz and 75MHz, both of which are used globally in the fabric. Phase offset settings are all '0'. When a register output from the 75MHz domain is 'used' in the 150MHz domain, is there a setup/hold time hazard? How closely matched are the edges of the two clock outputs? Are they close, not so close, or absolutely 'dead nuts on' ? I looked through the docs and the Xilinx website, and I couldn't find this information, including DS162 Table 50 (PLL Specifications). There is a Static Phase Offset spec in DS162, but nothing which specifically refers to output matching. Thanks for your help... SIGNATURE: README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369 Summary: 1. Read the manual or user guide. Have you read the manual? Can you find the manual? 2. Search the forums (and search the web) for similar topics. 3. Do not post the same question on multiple forums. 4. Do not post a new topic or question on someone else's thread, start a new thread! 5. Students: Copying code is not the same as learning to design. 6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please). 7. You are not charged extra fees for comments in your code. 8. I am not paid for forum posts. If I write a good post, then I have been good for nothing. |
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ISE内部的时序分析工具使用时钟不确定性,我相信这是你想要的。
时钟不确定地处理静态相位偏移和输出时钟抖动。 因此,当您的时钟被分析时,这些因素将被用于实施。 我会说边缘将是“接近”,但这是主观的,所以最好检查工具的确切数字。 这回答了吗? 以上来自于谷歌翻译 以下为原文 The timing analysis tools inside of ISE use clock uncertainty, which I beleive is what you're trying to get at. The clock uncertaintly takes care of the static phase offset and the output clock jitter. So when your clocks are analyzed, those factors will be taken into acocunt. I would say the edges will be "close", but that's subjective, so best to check the tools for an exact number. Does that answer it? |
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我的问题与时序分析和“时钟不确定性”关系不大。
我担心需要对从较慢时钟域到较快时钟域的信号进行特殊处理。 我并不担心绝对的“时钟不确定性”。 我担心同一PLL的两个输出之间的相位差。 如果可以说所有PLL输出都是由PLL内部的触发器驱动的 - 都具有相同的时钟 - 那么我会满意答案。 出于所有实际目的,这样的设计是'两个时钟上的死钟'对齐。 我认为你回答的问题和我想到的问题是相似的,但不完全一样。 在这种情况下,需要对时序分析器中的“竖起大拇指”或“大拇指向下” - 任何一个 - 进行质疑和假设,这将引导我们回到PLL输出 - 输出相位对齐的基本问题 。 这有意义吗? - 鲍勃埃尔金德 签名:新手的自述文件在这里:http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369总结:1。 阅读手册或用户指南。 你读过手册了吗? 你能找到手册吗?2。 搜索论坛(并搜索网页)以寻找类似的主题。 不要在多个论坛上发布相同的问题。 不要在别人的主题上发布新主题或问题,开始新的主题!5。 学生:复制代码与学习设计不同.6“它不起作用”不是一个可以回答的问题。 提供有用的详细信息(请与网页,数据表链接).7。 您的代码中的评论不需要支付额外费用。 我没有支付论坛帖子的费用。 如果我写一篇好文章,那么我一无所获。 以上来自于谷歌翻译 以下为原文 My question has very little to do with timing analysis and 'clock uncertainty'. I'm concerned about the need for special handling of signals which cross from the slower clock domain to the faster clock domain. I'm NOT worried about absolute 'clock uncertainty'. I AM worried about phase difference between two outputs of the same PLL. If it can be said that all PLL outputs are driven by flipflops internal to the PLL -- all with the same clock -- then I would be content with the answer. Such a design is a 'both clocks dead nuts on' alignment, for all practical purposes. I think the question you answered and the question I had in mind are similar, but not quite the same. In this case, a 'thumbs up' or 'thumbs down' -- either one -- from the timing analyser need to be questioned for assumptions and methodology, and this would lead us back to the underlying question of PLL output-output phase alignment. Does this make sense? - Bob Elkind SIGNATURE: README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369 Summary: 1. Read the manual or user guide. Have you read the manual? Can you find the manual? 2. Search the forums (and search the web) for similar topics. 3. Do not post the same question on multiple forums. 4. Do not post a new topic or question on someone else's thread, start a new thread! 5. Students: Copying code is not the same as learning to design. 6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please). 7. You are not charged extra fees for comments in your code. 8. I am not paid for forum posts. If I write a good post, then I have been good for nothing. |
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PLL的VCO是所有时钟输出的来源。
输出计数器(O [5:0]或CLKOUT {5:0])实际上就是你所说的触发器。 对你而言,每个人的输出延迟可能略有不同。 那些不同的输出延迟是我们用静态相位偏移解决的问题。 为了更进一步,这些输出计数器还需要驱动时钟缓冲器,例如BUFH,BUFG等。当然,需要考虑由于不同缓冲器引起的路由差异。 由于它们是两个不同的时钟缓冲器,因此它们可能在物理上看到的路由噪声也有微妙的变化。 我希望这可以解决你的问题的主要来源,即所有时钟都来自同一个时钟源。 从那时起,一切都能够为该时钟添加额外的偏斜和/或抖动。 以上来自于谷歌翻译 以下为原文 The PLL’s VCO is the source of all of the clock outputs. The output counters (O[5:0] or CLKOUT{5:0]) are effectively what you are calling flip flops. The kicker for you is that each may have slightly different output delays. Those different output delays are what we're addressing with the static phase offset. To take this one step further, those output counters additionally need to drive through clock buffers such as a BUFH, BUFG, etc. Of course routing differences due to different buffers will need to be taken into account. Since they’re two different clock buffers there’s also subtle variations in routing noise that they may physically see. I hope this addresses the main source of your question, though, that all of the clocks are derived off of the same clock source. Everything from that point on has the ability to add additional skew and/or jitter to that clock. |
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