Determining pin pitch for existing library parts

On 7/31/2012 5:54 AM, Krycek wrote:

I am very new to Eagle so still finding my way around it. One thing that currently has me confused is how to determine the pin pitch for a footprint thats in the library.

 

In this case I am using an F25HP package from the con-subd.lbr on a simple parallel breakout PCB im laying out but for the life of me I can't see a way either in the PCB layout or the library editor itself to determine the pin pitch that has been used for this package.

 

Any help would be appreciated as I can see me running into similar problems with other library packages that aren't on a standard 0.1" pitch.

 

You could...

1.  Adjust the grid settings (Turn it on if its not visible) to

something on the order of what you expect for the pin pitch then eyeball

it to get a rough idea.

2.  Open the library with the library editor,  pick the info command

tool, and select one of the holes/pads.   The info dialog will show you

the exact position of the hole/pad.    Note the coordinates and then

select an adjacent hole/pad.   Subtract the coordinates to get the pitch.

3.  Use the Mark tool to set a marker at one pin/pad.   After you set

the marker there should be a relative coordinate readout in the upper

left part of the window frame/tool bars.   The Relative coordinate will

be in the units of the current grid and will show you how far the mouse

pointer/cursor is from the marker.    You way want to hold down the Alt

key to use the alt grid for fine positioning.

Regards,

Jim

Seems like a lot of trouble to know the pitch of a component? Why not have this information available in a description of the part. Any part should have pad size, pitch and all other relevent information in a pop-up on request. After all if the part exists, the info exists.

One other thing, even if the part description mentions the pitch and other package information, there could be a mistake. I always measure pitch and pad sizes just to be sure. Most times the only way to be sure you get what you need is to make the part layout yourself.

Regards,

Bob Moreno

On 7/31/2012 9:33 AM, Bob Moreno wrote:

Seems like a lot of trouble to know the pitch of a component? Why not have this information available in a description of the part. Any part should have pad size, pitch and all other relevent information in a pop-up on request. After all if the part exists, the info exists.

 

Hi Bob,

The truth is that not everyone who makes libraries has the presence of

mind to include such information. I wrote a small standard for library

creation to try to elevate the overall quality of user submitted libraries.

One of the recommendations is to include a link to the datasheet or some

other documentation which can provide the finer details of a part.

You can find it under the Documentation section of:

www.cadsoftusa.com/downloads

hth,

Jorge Garcia

Hi Jorge, I saw and read your write-up, very helpful, thanks.

Regards,

Bob Moreno

On Tue, 31 Jul 2012 13:33:35 +0000, Bob Moreno wrote:

Seems like a lot of trouble to know the pitch of a component? Why not

have this information available in a description of the part. Any part

should have pad size, pitch and all other relevent information in a

pop-up on request. After all if the part exists, the info exists.

At a coarse level the package type (SO-8, SOT-23-6, etc) determines the

lead dimensions.

At a fine level, if you must go there for reasons of high reliability,

inexpensive manufacturing, whatever, all of the details of a part's

geometry on the board must be called out.

Ultimately the only libraries that you can trust are the ones that you've

vetted personally, and looking at the descriptions (which are only tied

to the reality by the diligence of the library designer) doesn't count.

If that last paragraph sounds too cynical for you -- enjoy your youth;

that's when you still have energy for fixing screwups caused by being too

trusting.

--

My liberal friends think I'm a conservative kook.

My conservative friends think I'm a liberal kook.

Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software

http://www.wescottdesign.com

Hi Tim, my point is that in other cad programs, library package descriptions are tied to actual specifications used when packages are being made. User descriptions are worthless I agree. I would like for the specifications as used in the actual package construction (and again already in the package) be available. This eliminates errors. In other cad programs I use, a pop-up can be called which defines the actual X, Y size of any pad in the package, as well as the actual pitch used, number of pads, rows/columns, etc. The person constructing the package can say it's a .5mm pitch, but if in reality it is 1mm, it doesn't matter because the program will give you the actual number no matter what the user said it is. Thses figures are already in the package, so why not be able to recall them? This makes personal vetting so unnecessary.

Regards,

Bob Moreno

Thanks for the info everyone. I am used to other PCB software that you can just use hotkeys to locate pad centers making this sort of thing extremely quick and easy.

Exactly!