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Changing Pin Assignments in a Package [message #165930] Thu, 02 June 2016 10:09 Go to next message
David Schwab
Messages: 4
Registered: April 2016
Junior Member
I'm using the 14-pin, DIP Quad NAND gate (74ALS00N) from part 74*00 in library 74xx-us in a schematic. The problem I'm having is that the pin assignments don't match the datasheet: for example, the package has the 2nd gate's IN1, IN2, and OUT pins assigned to pins 4,5, and 6, while the datasheet has them assigned to 5, 6, and 4. Here's the datasheet, so you can see what I mean: DM74ALS00A pdf, DM74ALS00A description, DM74ALS00A datasheets, DM74ALS00A view ::: ALLDATASHEET ::: ( http://pdf1.alldatasheet.com/datasheet-pdf/view/50914/FAIRCHILD/DM74ALS00A. html) I've actually never seen a chip with the pins assigned the way they are in this part: I'm pretty sure the assignments in the datasheet are based on the original Texas Instruments design from the 1970s, which is the de facto standard for this chip.

How can I fix the pin assignments to match the datasheet? I tried editing the part, and changing the pin mappings between the symbol and the package using the CONNECT button, but when I added the part to a new schematic, nothing was changed.

Thanks,

David

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Re: Changing Pin Assignments in a Package [message #165933 is a reply to message #165930] Thu, 02 June 2016 10:36 Go to previous messageGo to next message
warrenbrayshaw
Messages: 1760
Registered: January 2010
Location: New Zealand
Senior Member
On 2/06/2016 10:09 p.m., David Schwab wrote:
> I'm using the 14-pin, DIP Quad NAND gate (74ALS00N) from part 74*00 in library 74xx-us in a schematic. The problem I'm having is that the pin assignments don't match the datasheet: for example, the package has the 2nd gate's IN1, IN2, and OUT pins assigned to pins 4,5, and 6, while the datasheet has them assigned to 5, 6, and 4. Here's the datasheet, so you can see what I mean: DM74ALS00A pdf, DM74ALS00A description, DM74ALS00A datasheets, DM74ALS00A view ::: ALLDATASHEET ::: ( http://pdf1.alldatasheet.com/datasheet-pdf/view/50914/FAIRCHILD/DM74ALS00A. html) I've actually never seen a chip with the pins assigned the way they are in this part: I'm pretty sure the assignments in the datasheet are based on the original Texas Instruments design from the 1970s, which is the de facto standard for this chip.
>
> How can I fix the pin assignments to match the datasheet? I tried editing the part, and changing the pin mappings between the symbol and the package using the CONNECT button, but when I added the part to a new schematic, nothing was changed.
>
> Thanks,
>
> David
>
> --
> To view any images and attachments in this post, visit:
> https://www.element14.com/community/message/198594
>


Hi
Woops! - wrong forum. This forum is for making suggestions for changes
to the EagleCad software.

As for your issue. I suspect, if you did perform a save, then you are
getting the same named part from another instance of the eagle
libraries. Possibly from a previous install.

Place something in the device you are modifying so you can sure you are
adding from the library you have modified.

Check your Options>Directories...>Libraries to verify you don't have
more than one path to similarly named libraries.
The eagle.epf file that every project has containes used libraries so
that may be pointing you to another similarly named library.
Un-Use all the libraries.
Use - the desired libraries again.

HTH
Warren
Re: Changing Pin Assignments in a Package [message #165934 is a reply to message #165930] Thu, 02 June 2016 10:45 Go to previous messageGo to next message
kulky64
Messages: 3
Registered: June 2016
Junior Member
> ... while the datasheet has them assigned to 5, 6, and 4.
What? Where do you see this? To me it seems perfect match between Eagle and datasheet.

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Re: Changing Pin Assignments in a Package [message #165941 is a reply to message #165930] Thu, 02 June 2016 15:18 Go to previous messageGo to next message
Joern Paschedag
Messages: 1436
Registered: August 2008
Senior Member
Am 02.06.2016 um 12:09 schrieb David Schwab:
> I'm using the 14-pin, DIP Quad NAND gate (74ALS00N) from part 74*00 in library 74xx-us in a schematic. The problem I'm having is that the pin assignments don't match the datasheet: for example, the package has the 2nd gate's IN1, IN2, and OUT pins assigned to pins 4,5, and 6, while the datasheet has them assigned to 5, 6, and 4. Here's the datasheet, so you can see what I mean: DM74ALS00A pdf, DM74ALS00A description, DM74ALS00A datasheets, DM74ALS00A view ::: ALLDATASHEET ::: ( http://pdf1.alldatasheet.com/datasheet-pdf/view/50914/FAIRCHILD/DM74ALS00A. html) I've actually never seen a chip with the pins assigned the way they are in this part: I'm pretty sure the assignments in the datasheet are based on the original Texas Instruments design from the 1970s, which is the de facto standard for this chip.
>
> How can I fix the pin assignments to match the datasheet? I tried editing the part, and changing the pin mappings between the symbol and the package using the CONNECT button, but when I added the part to a new schematic, nothing was changed.
>
> Thanks,
>
> David
>
> --
> To view any images and attachments in this post, visit:
> https://www.element14.com/community/message/198594
>

Nothing wrong with the eagle library.

--
Mit freundlichen Grüßen / With best regards

Joern Paschedag
Re: Changing Pin Assignments in a Package [message #165948 is a reply to message #165941] Fri, 03 June 2016 09:00 Go to previous message
David Schwab
Messages: 4
Registered: April 2016
Junior Member
Oops, I linked to the wrong data sheet for the part that I have (the actual, physical chip): I see that the Eagle library is correct, but I think my chip has different pin assignments than the one in the library. I'll follow Warren's suggestion and make a new part. Sorry for the confusion on my end.

Thanks,

David

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