Re: gEDA-user: Defining parts with REALLY complicated pin labels

[Xtian Xultz <xultz@xxxxxxxxxxxx>]

Em Qua 17 Ago 2005 22:46, David D. Hagood escreveu:
> First of all:
>
> Thanks for creating gEDA - you guys saved me from following the path of
> sin and running a commercial EDA package!
>
> I am working on a couple of parts for a project I am designing, and will
> contribute them back as soon as I have "put them to the test" and gone
> from schematic to board with them.
>
> The first, the TI SN754410 quad half-H bridge, was pretty straightforward.
>
> But the second, a Microchip PIC16F688 - well, every pin (other than Vss
> and Vdd) has at least 2, and in some cases 5 functions, multiplexed by
> software. This leads to a couple of issues:
>
> 1) What do I use as the "pintype" attribute when a pin might be an
> input, an output, tristate, a clock, an analog input, or programming
> voltage, depending upon the mode?
>
I use "pas".

> 2) The "pinlabel" fields get pretty damn long when you have a pin like
> "RA0/AN0/C1IN+/ICSPDAT/ULPWU" - either this 14 pin part is going to be a
> mile wide in the schematic, or I have to come up with a way to break
> that attribute into a couple of lines. I tried making multiple
> "pinlabel" attributes, but that didn't pass muster for gsymcheck.

I put on PIC microcontrollers only the most important functions. In you 
example, only RA0/AN0. The designser must follow the datasheet to know all 
the capabilities of the chip, IMHO the symbol is only a guide, the most 
important is to have a schematic that you can understand and to generate a 
perfect netlist file. 
>
> Also, how do I add an inversion bar to a label? I tried using a leading
> "*", but that did not seem to work.

I place a line. Reduce the grid to 10 and draw a line over the label. The 
problem is that the text you see on the screen doenst have the same size that 
appears on the paper, so you must test on the paper if the line fits well.
>
> Lastly - and this is truly blue-sky dreaming - I have an infrastructural
> question: Given a part like a PIC, would it be possible to create some
> form of scripted part (in Scheme) that would allow the user to select
> what the functions of the pins were, and then create the appropriate
> labels for them, and possibly even emit the register setups for the
> part? It seems to me that this would really help make a multifunction
> part like a PIC pass DRC, as then the device could be tailored to the
> exact setup - inputs could be really marked as inputs, output as
> outputs, etc.

I dont have sufficient IQ to answer that question...