Re: gEDA-user: Symbols: mixed slotted elements and dedicated pins?

["John Luciani" <jluciani@xxxxxxxxx>]

On Jan 29, 2008 4:25 AM, Richard Rasker <rasker@xxxxxxxxxx> wrote:

> Usually, I try looking up a symbol with a similar layout, but I got a
> bit confused here. For example, there are two different CMOS 4053
> symbols. The 4053-1.sym features separate dual-channel switches,
> selectable by defining the slot. But how do I connect the Enable and VEE
> pins (#6 and 7, respectively) to an arbitrary other component? And how
> to connect the power pins? When I look into the .sym file, I see that
> VDD, VSS and VEE have been defined as nets (with Enable tied to VSS --
> which is not good). Does this mean that all VEE pins from multiple
> 4053's are automatically tied together?

It sounds like there is a mistake in 4053-1.sym.

Nets that are named the same get connected. What I do for power pins is
use a separate power symbol. Just make sure that both symbols have the
the same refdes. For digital symbols I usually have a separate page (or section)
for power symbols and the corresponding local decoupling caps.

I have a script that takes symbols with embedded power nets and
creates a series
of power symbols and non-power symbols. The script is called
create-np-symbols and is at
http://www.luciani.org/geda/util/util-index.html

> How do I define this device as four slotted opamp elements with
> dedicated standby and phantom ground pins? Or would I better create one
> big, 16-pin symbol incorporating everything?

You could make a four slotted op-amp symbol and a separate power/ground/standby
symbol. When you place the symbols in your schematic just keep the
refdeses the same.

Depending on the amount of peripheral circuitry a 16-pin symbol could
also work. If
there is a lot of peripheral circuitry around each op-amp then I would
do the two
symbol approach.

(* jcl *)

-- 
http://www.luciani.org


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