Sam Sattel @ autodesk.com discuss about the benefits of differential signals and how to route them in Eagle.
If you’re designing a high speed PCB, then chances are you’re working with the latest and most powerful technologies, like HDMI, USB3.0, Ethernet, or DDR. But with great power comes great responsibility! As a result, you’ll likely be dealing with issues like electromagnetic interference (EMI) and noise.
So what do you do about these problems? When you’ve got a bunch of noisy signals on your board and you need a way to protect the transmission of your data then you need to be using differential pairs. In this blog we’ll be looking at all of the great benefits for using differential pairs in your high speed design project, and how to route them in Autodesk EAGLE.
Designing a PCB layout is a work of engineering art, includes placing components and routing them through different layers. So when you assign the same job for different engineers, each one would make it in his own way. But sometimes when working on a complex design some help may be necessary to finish the work. Autodesk EAGLE provides an autorouter feature which may assist you in many cases.
The autorouter is a useful tool that creates many routing variations for the current component placement. However, it is not a completely replacement of manually routing method. It can help you in specific situations to augment your abilities, not replace them.
When to use the autorouter?
There are three main uses of the autorouter:
Optimizing Placement While there is no rule for placing the components of the circuits, you need to evaluate your placement to ensure that you can route all parts. Autorouter completion result could be used as an indicator of your parts placement, if it was 85% or greater this means you did a good job. If not, consider pushing your parts around.
Discovering Bottlenecks You can also use the autorouter to identify bottlenecks and other critical connection points that you might have missed when placing your components. Maybe you packed a couple of ICs too close together. Your autorouter can show you where you might need to leave more space between components.
When you are stuck on a section and don’t know how to route your parts, then you can call the autorouter to see how it takes care of the job, then try routing that same spot yourself with your new perspective. You might just find a strategy for your traces that you didn’t see before your autorouter gave it a try.
Using EAGLE Autorouter
Now when you find yourself stuck on some area or you feel that you need to optimize your placement or discover the bottlenecks, it is time to launch the autorouter. Follow these steps to know how it works:
Open your PCB layout (.brd) file from your Autodesk EAGLE Control Panel.
Select the Autorouter tool on the left-hand side of your interface to open the Autorouter Main Setup dialog.
There’s quite few settings here that you can adjust:
Preferred direction: if you need a specific direction of the route, like vertical or horizontal, select it for each layer or you can set it to Auto. N/A means that the autorouter will not use this layer.
Effort: this option defines how the autorouter will work, higher effort will take more time and will provide more more routing variances.
Number of threads: how many threads of the CPU you want the autorouter to use? This surely will affect the time it takes to finish.
After selecting your settings, press the Continue button.
Within the Routing Variants dialog, you’ll see a list of all the routing variations the autorouter will attempt. Select the Start button to begin the autorouting process.
Once the routing is complete, select the Evaluate button, and you’ll see your completion percentage in the bottom-left corner of the interface.
If you want to unroute your board you can use the Undo (Ctrl + Z), or use the RIPUP command. Just type RIPUP ; in the command line and all of your routed traces will convert back to airwires.
To learn more about routing and autorouting you can read this tutorial, it is a part of series about Autodesk EAGLE features and how to use it. You can also view the previous tutorial about placing components.
Since Autodesk acquired Eagle CAD, big changes have been made to Eagle CAD. Regardless of the new licensing system using subscription model, which was a subject to criticism by a lot of users, the new management of Eagle from Autodesk has successfully added a lot of demanding features that old team failed to bring out.
Eagle 8 came with a lot of new features like BGA auto-router and “Past Block Design” tool to add a complete block of connected components both in schematic and board.
The new release 8.1.1 brought PCB alignment tool to align a group of objects in different positions; top, bottom, left, right, center, and distribute horizontally / distribute vertically.
Another improvement in eagle 8.1.1 that deserves mention is that a new category has been added to DRC (Design Rule Check) called Airewire. It’s an important improvement because airwires is one of the most common things designer should be aware of. In older Eagle releases, you should work with your eyes wide open and never forget to hit ratsnest at the end of your work and read the magic sentence in the bottom corner “Ratsnest: Nothing to do !”.
Back to basics. Here is a tutorial on autodesk.com blog on how to read schematics:
The schematic forms the building block of every electrical circuit, and even if you aren’t designing one yourself, knowing how to read one is invaluable. And with some schematic reading knowledge in hand, you’ll be able to design, build and ultimately troubleshoot your way through your design logic before heading on to your PCB layout.
How to Read Your First Autodesk EAGLE Schematic – [Link]
Although the new Eagle subscription model by Autodesk will bring much-needed features to the software, many users after the announcement had decided to move their work to other alternatives, such as KiCad, Altium, Cadence, etc.
One of the challenges was to convert the libraries made by Eagle to be compatible with other software programs. SnapEDA solved that by offering a new free tool that translates Eagle libraries to KiCad, Altium, OrCad and other formats.
SnapEDA is a parts library for circuit board design provides free symbols, footprints, and 3D models for millions of electronic components. The goal behind SnapEDA is to build one trusted, canonical source of electronics design content that everyone can benefit from.
To convert your Eagle library just upload your file here, then you can re-download it in any format through your uploaded models page. The video below demonstrates the converting process:
Currently, all the uploaded parts will be public on SnapEDA until the private version is released. All parts are clearly marked as user-generated content and attributed to the uploader, and can be deleted at any time.
“We are big fans of Eagle and the new changes they’re making, and are confident that the subscription model will bring much-needed features to the software. But we also understand that it is (for many) a showstopper. Hopefully this free tool is helpful to those for whom this is the case.” – SnapEDA
After acquiring CadSoft in June 2016, Autodesk released a new version of EAGLE with new features that improve program functions and a new pricing plan.
The new version of Eagle added a modular design blocks feature to the schematic editor that allows you to quickly replicate sections of circuitry between multiple projects. Even better, any change you make stays synchronized between your schematics and PCB.
The route engine comes with new, interactive routing features that make it easy to design beautifully precise PCB layouts. It includes a whole set of trace clean-up tools that makes it much easier to tidy up your board and make adjustments to existing paths. There is also an automated loop removal, cornering for super-smooth tracks, quick and easy via placement while routing.
Autodesk said that upgrading EAGLE will be available as a monthly or yearly subscription, providing continuous updates and better support, and it said to be budget friendly. Which means that users will get more consistent and frequent updates backed with dedicated support from the PCB design pros at Autodesk, and cheaper than buying a cup of coffee every day for a year.
Many Eagle users found it a bad deal, because having the old Standard option will cost $100/year instead of the one-time $69 payment. Autodesk also killed the lower cost options for non-commercial use, what used to be a $169 version that was positioned for hobbyists.
“We know it’s not easy paying a lump sum for software updates every few years. It can be hard on your budget, and you never know when you need to have funds ready for the next upgrade.”
You can download the free version from here, but for anyone using Eagle for commercial purposes this is a big change. Even if you agree with the new pricing, a subscription model means you never actually own the software. This model will require licensing software that needs to phone home periodically and can be killed remotely. If you need to look back at a design a few years from now, you better hope that your subscription is valid, that Autodesk is still running the license server, and that you have an active internet connection.
Regarding new @ADSKEAGLE subscription plan: previously paid $1591.21 for 88 months == $18.08/mo. Moving to $65/mo? KICAD looks better.
Panelizing is done by machining a slot between two or more boards, but keep them attached by a small amount of PCB material (mousebites). I used to do it by hand: generated all the schematics into multiple sheets and then route the board and finally add the slots with mousebites in the PCB editor. I generally use slotwidth of 50 mil and the smallest drill possible (12 mil) 12.5 mil apart as breakingline. I tend to place the mousebites about 2cm from each other to maintain PCB strength.
sfcircuits.com compares the top 5 PCB CAD Programs, DipTrace, Eagle, Altium, Pads and Orcad:
There are several programs available that range from simple and intuitive to highly sophisticated.
They range from free or inexpensive to high-end/premium.
They come feature-less or feature-heavy.
All of the tools are different and unique in their own way. Ultimately, your needs and preferences should drive what CAD program you use. This guide is structured to help you decide which is optimal or explore alternatives.
After the acquisition, they redesigned the website and changed the domain name from cadsoftusa.com to cadsoft.io. It seems that Autodesk is going very fast toward sharing with community what they intend to do with Eagle CAD tool after a lot of debates about the future of Eagle CAD.
Now and after about one month of the acquisition, they announced the release of EAGLE beta (7.6.2). “A number of items are “in development” but we’re looking for feedback, so it was better to push these early!” stated by the announcement.
The new features in this beta release include net names on tracks in the PCB editor.
The 7.6.2 beta version introduced a new button. It’s called MAKE button.
MAKE button produces the necessary outputs for fabrication, assembly, test, etc and upload your design files (including schematic, PCB, BOM, etc) to your user profile on Autodesk’s Circuits.io site.
Another new button is called MCAD. This button will upload your design to ECAD.io which is an online Electrical CAD (ECAD) to Mechanical CAD (MCAD) file converter.
Visit eagle.io to see the announcement and to download the new beta version.
The video below demonstrates how MAKE button works.