Why do I need to draw the same symbol N times?

On Fri, 23 Sep 2016 08:47:48 +0200

Morten Leikvoll <mleikvol@yahoo.nospam> wrote:

You dont need to redraw the symbol. You just create a new component

and add the symbol + all the packages that work with this symbol at

the same component, then connect them correctly. This works, even if

some packages have more gnd/shield pins, cause every package is

connected separately.

As Rik Steenwinkel pointed out, that doesn't work with very many chips.

Microcontrollers, FPGAs, power supply chips being ominous examples.

Micros more often than not drop/gain a few port pins between package

variants. FPGAs ditto. Power supply chips often drop rarely used

feature pins. SPI FLASH chips tend to have a 'BUSY' signal on the higher

pincount package, which is dropped if you go to the smallest

pincount/footprint one. So the list is quite long.

In my original post I was specifically talking about packages with

different pin counts and signal pins going missing in the smaller

package.

But currently (7.x), if the symbol differs slightly betweeen

packages, you have to copy/make a new symbol, and add/remove pins.

Exactly. As it has always been the case. Hence my request: I'd like to

draw only one symbol and assign a package, even if the symbol has

more pins than the package. Then the schematics could grey out or even

completely hide the pins that are not available on the package.

In the software world copy-paste-massage-ing code is one of the cardinal

sins, and rightly so, why am I forced to do it with my hardware?

--

Zoltán Kócsi

Bendor Research Pty. Ltd.

On Fri, 23 Sep 2016 08:47:48 +0200

Morten Leikvoll <mleikvol@yahoo.nospam> wrote:

You dont need to redraw the symbol. You just create a new component

and add the symbol + all the packages that work with this symbol at

the same component, then connect them correctly. This works, even if

some packages have more gnd/shield pins, cause every package is

connected separately.

As Rik Steenwinkel pointed out, that doesn't work with very many chips.

Microcontrollers, FPGAs, power supply chips being ominous examples.

Micros more often than not drop/gain a few port pins between package

variants. FPGAs ditto. Power supply chips often drop rarely used

feature pins. SPI FLASH chips tend to have a 'BUSY' signal on the higher

pincount package, which is dropped if you go to the smallest

pincount/footprint one. So the list is quite long.

In my original post I was specifically talking about packages with

different pin counts and signal pins going missing in the smaller

package.

But currently (7.x), if the symbol differs slightly betweeen

packages, you have to copy/make a new symbol, and add/remove pins.

Exactly. As it has always been the case. Hence my request: I'd like to

draw only one symbol and assign a package, even if the symbol has

more pins than the package. Then the schematics could grey out or even

completely hide the pins that are not available on the package.

In the software world copy-paste-massage-ing code is one of the cardinal

sins, and rightly so, why am I forced to do it with my hardware?

--

Zoltán Kócsi

Bendor Research Pty. Ltd.

zoltan wrote on Sun, 25 September 2016 01:53

Hence my request: I'd like to

draw only one symbol and assign a package, even if the symbol has

more pins than the package. Then the schematics could grey out or even

completely hide the pins that are not available on the package.

By the time you specify which pins should be greyed out, you might as well

have made the minor modifications from the symbol with a little more or

little less pins.  If you're only changing a few pins, there isn't really a

problem to solve here.

You don't want Eagle to just assume that you intentionally used a symbol

with too many pins and not show you the remaining ones.  That would

circumvent useful error checking.  Also, if a different chip has fewer

pins, you most likely want to draw the symbol differently.  You may want to

make it a little smaller, change some of the labeling inside the symbol,

etc.

A good example is a voltage regulator.  The simple 3-pin variety can be

drawn more simply and smaller than one with a shutdown input, for example.

I wouldn't want the simple 3-pin version burdened with a greyed out

shutdown input.  I also wouldn't want it drawn bigger with inexplicable

extra space in the 3-pin usage case.

If the symbols are similar except for a few pins, then there isn't really a

problem here.  Copy and edit works fine.  If the symbols are substantially

different, then you're going to have to do some work for each case one way

or the other.

Quote:

In the software world copy-paste-massage-ing code is one of the

cardinal

sins, and rightly so,

Exactly.  This is the same thing.  Just like with software, you copy and

paste, then make a few minor edits to adapt to details of the situation.

--

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