Trying to add PLCC68 socket from the smd-special.lbr

Question

Hi. I'm new to Eagle. I know the very basics of how to use it, but I have some problems adding a part to my board. I wan't to add a PLCC68 socket, which is included in the smd-special library. I just want the empty socked and I can wire up all the connections manually.

However, the socket cannot be found when in schematics mode, where I would normally add it. I can only find it when in board design, and there I'm not allowed to add it. I get the error "Can't backannotate this operation. Please do this in the schematic!", which as I said is not possible because the part does not show up there.

Can I seriously not just add an unnamed socket to my board and have me wire up the connections manually? Do I really have to create a whole new part with every pin predefined? That would be insane, and incredibly frustrating for a newcomer like myself. I could see myself end up using hours figuring that out

The specific part I'm trying to add is PLCC-68 SMTL-TT. It's for a Motorola 68000 on a Neo Geo MV-1C.

shabaz · Accepted Answer

Hi Martin,

You do need to create a part (if one doesn't exist) to reflect what you want in the schematic, and then it will place the footprint in the board layout view. While your requirement is valid for very small circuits, it wouldn't scale to larger circuits without a high risk of error and is therefore a workflow that isn't supported in many CAD packages.

Some early low-cost CAD packages allowed you to place and wire package footprints manually, and there are still some software packages which do this. I think Sprint-Layout supports the type of workflow you want to do.

autodeskguest · Answer

Hi You can create a board without a schematic but you must only have a board editor open and not a schematic editor also because if they are 'consistent' (forward and back annotation is active and in play) you won't be able to add footprints to the board. FYI - These footprints are called elements on the board but called packages in the library. The exception to having the two editors open is once the schematic/board have become inconsistent (different),once acknowledged, Eagle will not consider the other and it is as if the other is not open. So now you have only a board open you can add packages to it. After the packages have been added you use the 'Signal' function to logically connect the pads/smd. This will draw an air-wire between your connection points so you can see what needs connecting with copper traces. Next you use the route command to route between the pads/smd. Having placed the signal wires previously you now can take advantage of some of the Eagle magic. Routing snaps to the nearby pads and even if you do not finish a route, the air wire reminds you what needs doing. Use the ratsnest function often in this case and the air-wires will be recalculated making it clear to you the routing that remains. Remember it can only inform you thus if you have informed eagle of all the electrical connections you desire by using the signal functionality. HTH Warren -- Web access to CadSoft support forums at www.eaglecentral.ca. Where the CadSoft EAGLE community meets.