What should I do with unconnected pins in Eagle?

Hi,

The RS-232 part of my schematics fails ERC. The error is:
ERROR: Sheet 1/1: unconnected INPUT Pin: IC2 T2IN
ERROR: Sheet 1/1: unconnected INPUT Pin: IC2 R2IN

Basically I am not using T2IN and R2IN on the MAX232, so Eagle gives an error. Should I just connect those to either VDD or GND?

Also, I recall that Orcad had the NC (No Connect) symbol, does Eagle has something similar? I am asking that in case I will get some routing trouble when connecting T2IN and R2IN to VDD/GND.

Thank You,

Vlad.

I have no experience with the MAX232 so all I recommend is reading the spec sheet. They usually mention what to do with unused pins. As far as eagle goes, you can just ignore the errors if the spec sheet says to leave them unconnected. The errors will not affect the PCB, they are just there to warn you in case you really wanted them connected somewhere.

Ambient said:

I have no experience with the MAX232 so all I recommend is reading the spec sheet. They usually mention what to do with unused pins. As far as eagle goes, you can just ignore the errors if the spec sheet says to leave them unconnected. The errors will not affect the PCB, they are just there to warn you in case you really wanted them connected somewhere.

Click to expand...

What do you suppose the spec sheet says to do with an unconnected output? This is an Eagle problem, not a real world problem. Many packages besides OrCAD also have the No Connect symbol. I would re-search the Eagle documentation or the error message explanation for the solution.

You can specify pins as NC when you design the part. It would be handy to have that option in the schematic editor.

You could make a new version of the part in the lib and specify the unused pins as NC. Not a nice solution.

Papabravo said:

What do you suppose the spec sheet says to do with an unconnected output? This is an Eagle problem, not a real world problem. Many packages besides OrCAD also have the No Connect symbol. I would re-search the Eagle documentation or the error message explanation for the solution.

Click to expand...

I have left pins in Eagle unconnected and get the same error, but as long as they do not really need to be connected you can just ignore it, can't you? It seemed to me that he thought he absolutely needed to fix the error before continuing in Eagle.

No, I didn't have to fix those errors to continue to layout. I just like to be consistent and remove all the possible errors. Actually I already finished the layout given those errors, I just left those unconnected (I also did it on the breadboard). I just wanted to know whether there is a trick to fix them

Found this online:

"If I have INPUT pins on an IC, but I don't want to connect it, how can I eliminate the message error "unconnected INPUT Pin"?
By convention, INPUT pins must be connected. If you have pins that can be optionally used but also left open, you should set them as PASSIVE. You need to do this is the library editor. Use the Change->Direction->pas to change the pins that you want to be passive."