Re: [PEDA] Autorouting or manual routing, or both?
Hi all, I agree with Remco, you always want to change something after the autorouter has finished. The DWIT command (do what I'm thinking) still has not been implemented :-) But I want to speak in favour of Swiss cheese, not only because of its excellent taste. It is true that an autorouter like e.g. SPECCTRA will not generate these parallel, evenly spaced bus structures on dense boards that you find on many hand-routed boards (especially PC motherboards, where you have all the space of the world for routing), which results in far less vias than what an autorouter will produce. But is this really desirable? There are pros and cons for both approaches. In very high speed design, every via creates a tiny reflection on the signal that may be intolerable with signal frequencies of several 100 MHz and above, whereas with frequencies below 100 MHz this will probably not be a critical issue. On the other hand, parallel bus structures can cause crosstalk problems hard to debug, which will simply not be there if the board was autorouted like Swiss cheese. Critical signals like fast clock traces or fast line interfaces I always route manually before invoking the autorouter. Of course also these signals can be routed satisfactory by a good autorouter, but it is necessary to define very precise rules for every critical signal and having purchased the router option needed to enable it to follow these rules (FST option with SPECCTRA, this option being about the same price as the complete router package including all other options). Gisbert Auge N.A.T. GmbH Remco v/d Heuvel R.vd.Heuvel@fusion-electAn: Protel EDA Forum [EMAIL PROTECTED] ronics.nl Kopie: Thema: Re: [PEDA] Autorouting or manual routing, or both? 22.01.2002 08:20 Bitte antworten an Protel EDA Forum Dear Matt, Normally I only route the boards by hand (4 6 layers) , my expierence with autorouting utillities (not only Protel) is that you still want to change tracks which you don't like so you will wind up re routing the whole board :) The only thing i sometimes use the autorouter for is routing the databus on the pcb, only if there aren't any other tracks routed or else you get your swiss cheese... Remco van den Heuvel. Hardware Engineer. Please feel welcome to visit our website at: http://www.fusionelectronics.org --- Willem Alexanderweg 87, NL-3945 CH Cothen email: [EMAIL PROTECTED] tel: (+31)343590600 fax (+31)343578599 --- - Original Message - From: Matt Polak [EMAIL PROTECTED] To: Protel EDA Forum [EMAIL PROTECTED] Sent: Monday, January 21, 2002 4:51 PM Subject: [PEDA] Autorouting or manual routing, or both? Hey folks, It seems that a majority of you are doing some very dense, high-speed layouts with 4-6 layers being quite a common occurrence. I'm just wondering how much you typically route by hand, and how much you let the auto-router whack away at. Being primarily self-taught in the ways of Protel, and with the help of a few 'older school' engineer friends here and there, I've done a number of successful design layouts thus far, but these have been relatively simple 2 and 4 layer designs without many small-pitch/high pin-count devices. I'm moving more towards laying out more high-speed designs in the near future where a lot of stuff needs to be fit into a small place, and all connect together without traces and vias meandering all over. When I look at sample six layer boards (such as the 5407 EVM reference design Motorola has released) the bussing and interconnects are extremely elegant and efficient in appearance. For fun, I unrouted the 5407 board and then let the autorouter chew on it. It immediately made 'via swiss-cheese' out of the board and created little more than a large mess. I'm GUESSING quite a bit of these sort of designs are laid out by hand, or at least pre-routed
Re: [PEDA] Autorouting or manual routing, or both?
At 10:51 AM 1/21/2002 -0500, Matt Polak wrote: It seems that a majority of you are doing some very dense, high-speed layouts with 4-6 layers being quite a common occurrence. I'm just wondering how much you typically route by hand, and how much you let the auto-router whack away at. I typically do 100 in^2 4 layer designs, with a few 6 layer. I also do other ones that range from 4 to 30 in^2, 2 and 4 layer. I usually let the autorouter do as much as possible on the multilayer boards, then clean up the mess and route the remaining traces. Rediculous routes that run all around the perimiter of the board to go only a short distance are common, even with 6 layers. Maybe my route setup is not correct for the job. I have done a number of boards that had a wild mixture of pad pitches, which makes the router's job a lot harder. Being primarily self-taught in the ways of Protel, and with the help of a few 'older school' engineer friends here and there, I've done a number of successful design layouts thus far, but these have been relatively simple 2 and 4 layer designs without many small-pitch/high pin-count devices. I'm moving more towards laying out more high-speed designs in the near future where a lot of stuff needs to be fit into a small place, and all connect together without traces and vias meandering all over. I don't know if letting the autorouter start on this and then fix it up manually is a smart way to go. I guess I just keep hoping the autorouter will do a great job someday, but the fixup often takes a while. If you have a lot of differential pairs, terminated lines and mandated trace delays, then maybe a total manual route is the way to go. Otherwise, route all critical stuff manually first, then let the autorouter complete it. Jon * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 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/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
[PEDA] Autorouting or manual routing, or both?
Hey folks, It seems that a majority of you are doing some very dense, high-speed layouts with 4-6 layers being quite a common occurrence. I'm just wondering how much you typically route by hand, and how much you let the auto-router whack away at. Being primarily self-taught in the ways of Protel, and with the help of a few 'older school' engineer friends here and there, I've done a number of successful design layouts thus far, but these have been relatively simple 2 and 4 layer designs without many small-pitch/high pin-count devices. I'm moving more towards laying out more high-speed designs in the near future where a lot of stuff needs to be fit into a small place, and all connect together without traces and vias meandering all over. When I look at sample six layer boards (such as the 5407 EVM reference design Motorola has released) the bussing and interconnects are extremely elegant and efficient in appearance. For fun, I unrouted the 5407 board and then let the autorouter chew on it. It immediately made 'via swiss-cheese' out of the board and created little more than a large mess. I'm GUESSING quite a bit of these sort of designs are laid out by hand, or at least pre-routed to give the auto-router a sense of direction? Can anyone offer some basic pointers to getting started into planning and laying out PCBs for multi-layer, high-speed designs such as these? I have no idea where one would really even start with something like this. It seems most of the important knowledge gets passed directly from engineer to engineer; there are certainly no university classes (that I know of, anyway) that teach you how to lay out a dense, 6 layer board. :/ I appreciate the patience and wisdom of those who remember once being where I am now, who are willing to take the time to pass some of the tips and tricks down the engineering family tree. Thanks again for any pointers anyone can provide (either through the list, or privately.) Best regards, -- Matt * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 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/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Autorouting or manual routing, or both?
At 10:51 AM 1/21/2002 -0500, Matt Polak wrote: It seems that a majority of you are doing some very dense, high-speed layouts with 4-6 layers being quite a common occurrence. I'm just wondering how much you typically route by hand, and how much you let the auto-router whack away at. I don't know about the majority, many of us are doing simple designs. We do both, but the vast majority of our designs are hand-routed. Sometimes, perhaps, we should be autorouting these boards, but we have a preference Being primarily self-taught in the ways of Protel, and with the help of a few 'older school' engineer friends here and there, I've done a number of successful design layouts thus far, but these have been relatively simple 2 and 4 layer designs without many small-pitch/high pin-count devices. I'm moving more towards laying out more high-speed designs in the near future where a lot of stuff needs to be fit into a small place, and all connect together without traces and vias meandering all over. It may be some time before you see an autorouter that will be fully satisfactory. At the present time, autorouters are especially good with boards that are complex in terms of numbers of connections but do not require space and layer optimization. In other words, they have room. Perhaps a company wants to make a test fixture, it has lots of parts but only a few are going to be made. In that case, the improved layout quality possible with hand routing is not cost-effective. It's not just a matter of aesthetics. Good manual routing will, given the present state of the art, typically have shorter track lengths and fewer vias. As autorouter technology advances, I expect this advantage to be lost. How long it will take, I do not know. When I look at sample six layer boards (such as the 5407 EVM reference design Motorola has released) the bussing and interconnects are extremely elegant and efficient in appearance. For fun, I unrouted the 5407 board and then let the autorouter chew on it. It immediately made 'via swiss-cheese' out of the board and created little more than a large mess. I'm GUESSING quite a bit of these sort of designs are laid out by hand, or at least pre-routed to give the auto-router a sense of direction? Probably. But Protel's current router, under some conditions, can make fairly pretty boards. And that board may have been routed, say, with Specctra, which can cost, by itself, substantially more than the whole Protel suite. Can anyone offer some basic pointers to getting started into planning and laying out PCBs for multi-layer, high-speed designs such as these? I have no idea where one would really even start with something like this. It seems most of the important knowledge gets passed directly from engineer to engineer; there are certainly no university classes (that I know of, anyway) that teach you how to lay out a dense, 6 layer board. :/ I appreciate the patience and wisdom of those who remember once being where I am now, who are willing to take the time to pass some of the tips and tricks down the engineering family tree. I'll try to pull something out of my head. I tend to place and route at the same time, placing components that seem to naturally go together -- perhaps they share a bus or busses -- and making the placement as tight as might be reasonable. At least I do enough routing, if any is necessary, to satisfy myself that this section of the board is going to route properly and efficiently. I might reassign gates or I/O ports at this time. These sections are then arranged in the board space. As a result, you might see, with one of my designs, tight space and empty space. This is because tighter, in general, is better. One can always, if it makes a difference, spread parts out, though usually it is not worth the effort. But making a design tighter can be anywhere from time-consuming to impossible. So aim tight. It's also typically better, when done intelligently, from a noise perspective. [EMAIL PROTECTED] Abdulrahman Lomax Easthampton, Massachusetts USA * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 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/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Autorouting or manual routing, or both?
Matt I am a circuit/system designer who is is self-taught on PCB design. I design my own pcb's because I design portable electronics and the flexibility of placing the components at the time I'm designing the electronic package, etc. gives me some incredibly efficient packaging results. I only design portables. I recently used Protel Successfully to route a Pentium-III Portable mainboard with 12 layers and several BGA devices. The first spin of the board booted Windows. If I were to contract out to a pure PCB designer, then I would have much less flexibility in the overall design, electronic, mechanical, and interconnect. SO I do it myself first, then contract out for production once I get the design up and running. I have had some serious battles with Protel software. But I have set up and run the autorouter, and once when I sent a board out and had the SPECCTRA autorouter run, the difference between the two was not as great as I would have guessed. Remember, that's from a layman in terms of PCB routing efficiency. Personally, I am going to give the next release of Protel a long, hard look. I have resisted the move to PADS because of the expense and learning curve - I have been using Protel for several years. -Original Message- From: Matt Polak [mailto:[EMAIL PROTECTED]] Sent: Monday, January 21, 2002 9:51 AM To: Protel EDA Forum Subject: [PEDA] Autorouting or manual routing, or both? Hey folks, It seems that a majority of you are doing some very dense, high-speed layouts with 4-6 layers being quite a common occurrence. I'm just wondering how much you typically route by hand, and how much you let the auto-router whack away at. Being primarily self-taught in the ways of Protel, and with the help of a few 'older school' engineer friends here and there, I've done a number of successful design layouts thus far, but these have been relatively simple 2 and 4 layer designs without many small-pitch/high pin-count devices. I'm moving more towards laying out more high-speed designs in the near future where a lot of stuff needs to be fit into a small place, and all connect together without traces and vias meandering all over. When I look at sample six layer boards (such as the 5407 EVM reference design Motorola has released) the bussing and interconnects are extremely elegant and efficient in appearance. For fun, I unrouted the 5407 board and then let the autorouter chew on it. It immediately made 'via swiss-cheese' out of the board and created little more than a large mess. I'm GUESSING quite a bit of these sort of designs are laid out by hand, or at least pre-routed to give the auto-router a sense of direction? Can anyone offer some basic pointers to getting started into planning and laying out PCBs for multi-layer, high-speed designs such as these? I have no idea where one would really even start with something like this. It seems most of the important knowledge gets passed directly from engineer to engineer; there are certainly no university classes (that I know of, anyway) that teach you how to lay out a dense, 6 layer board. :/ I appreciate the patience and wisdom of those who remember once being where I am now, who are willing to take the time to pass some of the tips and tricks down the engineering family tree. Thanks again for any pointers anyone can provide (either through the list, or privately.) Best regards, -- Matt * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 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/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Autorouting or manual routing, or both?
A very good website that deals with high speed design is www.signalintegrity.com. It is hosted by Dr Howard Johnston and has articles on specific aspects of PCB design like terminations, bypassing, planes, routing impedance etc. ___ Clive Broome IDT Sydney Design CentrePh: +61 2 9763 3513 8 Bayswater Dr, HomebushFax:+61 2 9763 3409 Sydney, NSW, 2127 Email:[EMAIL PROTECTED] Australia ___ Matt Polak [EMAIL PROTECTED] on 01/22/2002 01:51:20 AM Please respond to Protel EDA Forum [EMAIL PROTECTED] To: Protel EDA Forum [EMAIL PROTECTED] cc:(bcc: Clive Broome/sdc) Subject: [PEDA] Autorouting or manual routing, or both? Hey folks, It seems that a majority of you are doing some very dense, high-speed layouts with 4-6 layers being quite a common occurrence. I'm just wondering how much you typically route by hand, and how much you let the auto-router whack away at. Being primarily self-taught in the ways of Protel, and with the help of a few 'older school' engineer friends here and there, I've done a number of successful design layouts thus far, but these have been relatively simple 2 and 4 layer designs without many small-pitch/high pin-count devices. I'm moving more towards laying out more high-speed designs in the near future where a lot of stuff needs to be fit into a small place, and all connect together without traces and vias meandering all over. When I look at sample six layer boards (such as the 5407 EVM reference design Motorola has released) the bussing and interconnects are extremely elegant and efficient in appearance. For fun, I unrouted the 5407 board and then let the autorouter chew on it. It immediately made 'via swiss-cheese' out of the board and created little more than a large mess. I'm GUESSING quite a bit of these sort of designs are laid out by hand, or at least pre-routed to give the auto-router a sense of direction? Can anyone offer some basic pointers to getting started into planning and laying out PCBs for multi-layer, high-speed designs such as these? I have no idea where one would really even start with something like this. It seems most of the important knowledge gets passed directly from engineer to engineer; there are certainly no university classes (that I know of, anyway) that teach you how to lay out a dense, 6 layer board. :/ I appreciate the patience and wisdom of those who remember once being where I am now, who are willing to take the time to pass some of the tips and tricks down the engineering family tree. Thanks again for any pointers anyone can provide (either through the list, or privately.) Best regards, -- Matt * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 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/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Re: [PEDA] Autorouting or manual routing, or both?
Dear Matt, Normally I only route the boards by hand (4 6 layers) , my expierence with autorouting utillities (not only Protel) is that you still want to change tracks which you don't like so you will wind up re routing the whole board :) The only thing i sometimes use the autorouter for is routing the databus on the pcb, only if there aren't any other tracks routed or else you get your swiss cheese... Remco van den Heuvel. Hardware Engineer. Please feel welcome to visit our website at: http://www.fusionelectronics.org --- Willem Alexanderweg 87, NL-3945 CH Cothen email: [EMAIL PROTECTED] tel: (+31)343590600 fax (+31)343578599 --- - Original Message - From: Matt Polak [EMAIL PROTECTED] To: Protel EDA Forum [EMAIL PROTECTED] Sent: Monday, January 21, 2002 4:51 PM Subject: [PEDA] Autorouting or manual routing, or both? Hey folks, It seems that a majority of you are doing some very dense, high-speed layouts with 4-6 layers being quite a common occurrence. I'm just wondering how much you typically route by hand, and how much you let the auto-router whack away at. Being primarily self-taught in the ways of Protel, and with the help of a few 'older school' engineer friends here and there, I've done a number of successful design layouts thus far, but these have been relatively simple 2 and 4 layer designs without many small-pitch/high pin-count devices. I'm moving more towards laying out more high-speed designs in the near future where a lot of stuff needs to be fit into a small place, and all connect together without traces and vias meandering all over. When I look at sample six layer boards (such as the 5407 EVM reference design Motorola has released) the bussing and interconnects are extremely elegant and efficient in appearance. For fun, I unrouted the 5407 board and then let the autorouter chew on it. It immediately made 'via swiss-cheese' out of the board and created little more than a large mess. I'm GUESSING quite a bit of these sort of designs are laid out by hand, or at least pre-routed to give the auto-router a sense of direction? Can anyone offer some basic pointers to getting started into planning and laying out PCBs for multi-layer, high-speed designs such as these? I have no idea where one would really even start with something like this. It seems most of the important knowledge gets passed directly from engineer to engineer; there are certainly no university classes (that I know of, anyway) that teach you how to lay out a dense, 6 layer board. :/ I appreciate the patience and wisdom of those who remember once being where I am now, who are willing to take the time to pass some of the tips and tricks down the engineering family tree. Thanks again for any pointers anyone can provide (either through the list, or privately.) Best regards, -- Matt * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 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/proteledaforum@techservinc.com * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
