# CADSOFT EAGLE libraries searching best practices

I just started to learn how to use EAGLE PCB software.

The device I wanted to draw as the first try containing two elements that are not in the libraries provided with Eagle out of the shelf: ATtiny861A and TDA5051A.

Most of the searches drives me to element14 site which is as I understand one of the most trusted for Eagle packages (as it is a main Asia Passific region CADSOFT seller). However NXP's library and Atmel library which I downloaded from element14 site does not contain those elements. There are ATtiny26 which is similar to ATtiny861A from the pinout and packaging point of view but I have nothing for TDA5051A.

I could expect that almost any component I can even imagine already was created by someone earlier. So I just have to find it in the right way to avoid extra job creating this element by my self and avoid some mistakes which I can make or someone can make.

So the questions are:

• What is the best practice to find libraries for Eagle?

• How can I be sure that the library I found is a good quality?

• Just make your own, it's not hard. – Matt Young Mar 29 '15 at 14:13
• Why is this being downvoted without explanation? – pjc50 Mar 29 '15 at 14:16
• Thanks, @MattYoung! But is it any good practice for such a newbie as my self? And it is always much faster and mostly safer to take already designed element instead of making it. – Roman Matveev Mar 29 '15 at 14:16
• Using somebody elses libraries may be marginally faster, but it's definitely not safer. You have to check every part you use from a library to make sure the footprint and pin out is correct. Or you can just circumvent that process and make your own. – Matt Young Mar 29 '15 at 14:22
• @MattYoung, that's all right! But my experience is that I always tend to skip some not very important steps making an element to safe some time and sometimes misses some common rules. This is basing on my PCAD experience. – Roman Matveev Mar 29 '15 at 14:26

What is the best practice to find libraries for Eagle?

• First you must be sure that your device is not in eagle libraries using good search, For example if you want to add 7805 5v regulator, You must search like this: *7805* That because certain manufacturer have their own extension that you don't know.
• If you didn't find your device or reasonable alternative (you can use for example atmega8 device instead of atmega328 device.Try to use famous public libraries produced by:
• Also a good practice is to memorize if the part you want to use is used in previous open source board, If answer is Yes then go and export used parts there from ULP.

• When you build your own library keep in mind that there is a reference library in eagle called Ref-packages.lib that have most of electronics packages which make create new libraries much easier.

How can I be sure that the library I found is a good quality?

Just print footprint on a paper and make sure that every thing is OK, or you can make sure from eagle that physical footprint is typical to part description from datasheet.

• Sorry if I missed something: what is ULP? – Roman Matveev Mar 30 '15 at 15:07
• In EAGLE it's User Language Programs (ULP). Every ULP do some specific function like the one I mentioned for exporting Used devices in other eagle design. – Yahya Tawil Mar 31 '15 at 6:33
• Its also happens that the chip manufacturer provides an Eagle library. So if you are dealing with a "complex" part, it may be worth to take a look on their site. – Rev1.0 Apr 2 '15 at 6:53