Re: [PEDA] Using the Equalize net lengts function
At 04:40 AM 1/6/2004, you wrote: In the near future I am going to layout a board (in Protel 99SE) with high speed digital signals (PC motherboard). The tracks in some of the buses must be of same length due to the high speeds and I must use the Equalize Net Lengts function. I have never used the function so I do not know if it works or not in general. But depending upon the type of PC motherboard you are doing, it may be guaranteed to not work for you. In many of the newer chipsets, you need to equate the lengths from die to die, which means you need to take into account the trace length of the signal on the package itself, which is unique for each signal. The bottom line is that in order for the nets to be of equal lengths, the traces on the board may need to be of quite different lengths. Unless the function allows you to add a unique offset to each net, which I have not seen in the documentation, you will not be able to use it. Another area where you are going to run into problems is in routing the memory bus. The length has to be equal from the die on the memory controller to the pad on the memory connector. However, this signal path goes through a resistor, so you are actually working with the sum of the length of two nets on the board plus the package offset as the entity that you need to equalize. Good luck. Hamid (Been there, done that, did not enjoy it one bit) * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Using the Equalize net lengts function
At 04:40 AM 1/6/2004, you wrote: In the near future I am going to layout a board (in Protel 99SE) with high speed digital signals (PC motherboard). The tracks in some of the buses must be of same length due to the high speeds and I must use the Equalize Net Lengts function. Anybody who has experiences using this function and maybe have some hints for optimising for best results ?? Yes, we have used it. For those who don't know, this function adds meanders to track, i.e., the track wiggles back and forth with a controllable pitch and side-to-side deviation. The function is a command in the Tools menu; when run, it attempts to match the length of nets identified by the Matched Net Length design rule. You must set up this design rule prior to running the process. Track segments will be added to all nets that are shorter than the longest net in the set of nets. The tool will look for places along the net where there is room to add the defined meanders, so you might want to think about providing such space. You can see your net lengths in the Netlist Status Report, to verify that the job has been done to your satisfaction. If you need to make some adjustments, then you'll check your work with that report. It helps if the nets involved have names such that they will appear next to each other in the report * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Using the Equalize net lengts function
Using the automatic feature in Protel does work but sometimes does not give you what you really need. The way I do this is to define a class with the nets you need to equalize. Then add a rule for the min and max length you need for this class in Rules/High Speed/Length Constrant. Then define max/min length to some silly number that will give you an error when you run a DRC check. Switch off all DRC except for Length Constraint and switch on Online DRC. Now you will get your netclass producing errors on all its nets and you will see what sort of average length you will need to work to. Set some more appriopriate value in your rules and then you can start to manually shorten the long nets or lengthen the short nets etc. Then you can pick up a net from Browse PCB/Violations and use Edit/Move/Break to lengthen a section or Edit/Move/End to shorten a section. One bug is the net you are altering falls to the bottom of the violations list after the Online DRC has done its thing so you might think you have altered it to the correct lenght but its still out of range. BR Clive Abd ul-Rahman Lomax [EMAIL PROTECTED] on 07/01/2004 09:58:11 AM Please respond to Protel EDA Forum [EMAIL PROTECTED] To: Protel EDA Forum [EMAIL PROTECTED] cc:(bcc: Clive Broome/sdc) Subject: Re: [PEDA] Using the Equalize net lengts function At 04:40 AM 1/6/2004, you wrote: In the near future I am going to layout a board (in Protel 99SE) with high speed digital signals (PC motherboard). The tracks in some of the buses must be of same length due to the high speeds and I must use the Equalize Net Lengts function. Anybody who has experiences using this function and maybe have some hints for optimising for best results ?? Yes, we have used it. For those who don't know, this function adds meanders to track, i.e., the track wiggles back and forth with a controllable pitch and side-to-side deviation. The function is a command in the Tools menu; when run, it attempts to match the length of nets identified by the Matched Net Length design rule. You must set up this design rule prior to running the process. Track segments will be added to all nets that are shorter than the longest net in the set of nets. The tool will look for places along the net where there is room to add the defined meanders, so you might want to think about providing such space. You can see your net lengths in the Netlist Status Report, to verify that the job has been done to your satisfaction. If you need to make some adjustments, then you'll check your work with that report. It helps if the nets involved have names such that they will appear next to each other in the report * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[EMAIL PROTECTED] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
