change a different symbol in a downloaded library

[Anonymous]

I downloaded a library for a 16-pin SOIC device from Digikey. I add this library in my Eagle 7.8.0 all right. However, I do not like their symbol and draw a new symbol with 16 pins. Then, I go back to the device library and try to add this new symbol but an error message pop up says "adding the new symbol will exceed the minimum number of 16 pads available in the package variant". I am sure that the symbol I created has only 16 pins. Could someone help me about this issue?

Thanks,

Bill 

[one-of-the-robs · Accepted solution]

Hi Bill,

It sounds like what you tried to do was to add an "alternate" symbol alongside the existing symbol in the device editor. This is not a valid concept for Eagle.

Each device contains a set of symbols that all, collectively, make up the whole device. An example of this would be a 7400 (TTL quad NAND chip) where the device has four copies of the 2-input NAND symbol and one pair-of-power-pins symbol. In your schematic, you would use the four gates in various places and, optionally, place the power pins either on one of them or elsewhere.

There is no concept of a device with "alternate" symbols to choose from.

This is, of course, completely the opposite of the package situation. Each device must fit entirely into one package but you can have several different packages to choose from. In the 7400 case, they would be DIL14, SOIC14, SSOP14 etc.

If you don't like the symbol in the library you downloaded, there are three ways to approach this:

1) Create a new symbol and a new device, then place that new symbol in the new device with the existing package and hook it up.

2) Create a new symbol only. Edit the device, DELETE the existing symbol and put your new one in it place. Then hook it up.

3) Edit the existing symbol, removing all the bits you don't like but leaving the pins. Draw your new symbol with the existing pins. The device will inherit the change automatically.

The first option is the preferred one - see, for example, the RCL or logic libraries with their "EU" and "US" devices. The third option is probably the quickest from scratch, but the second is the easiest from where you are.

Cheers,

Rob