KiCad Spice, Anyone Tried It?

onsdag den 3. juni 2020 kl. 04.04.47 UTC+2 skrev Ricketty C:
> On Tuesday, June 2, 2020 at 1:56:49 PM UTC-4, Lasse Langwadt Christensen wrote:
> > tirsdag den 2. juni 2020 kl. 13.46.04 UTC+2 skrev Clifford Heath:
> > > On 2/6/20 6:01 pm, Ricketty C wrote:
> > > > I didn't realize KiCad has a spice simulator built in.
> > > 
> > > Not quite. It's an export to LTSpice. No, I haven't used it.
> > > I Spice little things, but by the time I get to Kicad I pretty-much know 
> > > what I want, and it doesn't need Spice-ing.
> > > 
> > > I'm pretty keen on trying out the Kicad/JLCPCB combination soon though.
> > > It seems a pity that though they publish their parts list (even 
> > > including current stock levels!) they don't publish a matching Kicad 
> > > library for any of the parts - and the standard Kicad footprints use a 
> > > different centroid/rotation standard.
> > > 
> > 
> > most part are standard footprints so just pick the part and the right footprint
> > afaiu the rotation is different because Kicad uses the standard for where pin 1 should be, jlcpcb uses the way the part is in the tape
> 
> I'm not sure what you are saying with this.  Are you talking about the contents of the XYRS file that the tool spits out?  I would expect that to indicate the orientation on the PCB.  Are you saying the jlcpcb program indicates how much to turn the part rather than where it should be?  I'm just not following this. 
> 

the files has placement and rotation, Kicad and jlcpcb has different definitions of what 0 degrees rotation means


> 
> > I use a script to spit out BOM and placement file with corrected rotation, just need to add the lcsc part number as a field to the schematic symbol
> > 
> > jlcpcb has previewer to show the placement some you can check it and I believe they also do a manual check if the silkscreen shown the pin 1 location
> 
> I've never understood why pin 1 orientation is such a complex issue.  But I do know it fails from time to time. 
> 

for say a TQFP there's four ways you can decide to call 0 degrees, which one 
do you pick?

On 03/06/20 08:34, Ricketty C wrote:
> I guess I spoke too soon about KiCad being easy to pick up... well it isn't
> about picking up really.  It's about issues of multiple pages.  They don't
> really support a flat, multi-page schematic.  It must be hierarchical.  So to
> have a two page schematic, you must have a top sheet and one or more lower
> sheets.

As someone that hasn't used KiCad yet, but expects to soon, my
comment is "excellent" :)

I have three peeves about many schematics that I see:
   - principal signal flow in any random direction
   - if a wire leaves one schematic, it isn't clear which
     other schematic(s) is reappears on
   - signal/bus wires that are named but not visually connected

The latter really pisses me off, since on a PDF I have to
use ctrl-f to understand connectivity, and the schematic cannot
be usefully printed out.

No, it isn't merely modern diagrams that do that, you also
find it in old Tek schematics.

On Wed, 3 Jun 2020 10:36:07 +0100, Tom Gardner
<spamjunk@blueyonder.co.uk> wrote:

>On 03/06/20 08:34, Ricketty C wrote:
>> I guess I spoke too soon about KiCad being easy to pick up... well it isn't
>> about picking up really.  It's about issues of multiple pages.  They don't
>> really support a flat, multi-page schematic.  It must be hierarchical.  So to
>> have a two page schematic, you must have a top sheet and one or more lower
>> sheets.
>
>As someone that hasn't used KiCad yet, but expects to soon, my
>comment is "excellent" :)
>
>I have three peeves about many schematics that I see:
>   - principal signal flow in any random direction
>   - if a wire leaves one schematic, it isn't clear which
>     other schematic(s) is reappears on
>   - signal/bus wires that are named but not visually connected
>
>The latter really pisses me off, since on a PDF I have to
>use ctrl-f to understand connectivity, and the schematic cannot
>be usefully printed out.
>
>No, it isn't merely modern diagrams that do that, you also
>find it in old Tek schematics.
>

I hate hierarchicals and busses and any abstraction that hides what's
actually on the board. I do everything flat... currently a 31-page
schematic with five basically identical output channels, each on its
own sheet. I know exactly where R114 is.

I do start a schematic with sheet 1 being the block diagram and sheet
list/table of contents. Sheets have both numbers and names in the PADS
pulldown menu.

The old Tek and HP schematics just sort of suggested where an offpage
signal went. There was no formal concept of a net name.

Some schematic editors are just plain ugly. The old ORCAD was ghastly,
and dangerous.



-- 

John Larkin         Highland Technology, Inc

Science teaches us to doubt.

  Claude Bernard
  

On 03/06/20 13:18, jlarkin@highlandsniptechnology.com wrote:
> On Wed, 3 Jun 2020 10:36:07 +0100, Tom Gardner
> <spamjunk@blueyonder.co.uk> wrote:
> 
>> On 03/06/20 08:34, Ricketty C wrote:
>>> I guess I spoke too soon about KiCad being easy to pick up... well it isn't
>>> about picking up really.  It's about issues of multiple pages.  They don't
>>> really support a flat, multi-page schematic.  It must be hierarchical.  So to
>>> have a two page schematic, you must have a top sheet and one or more lower
>>> sheets.
>>
>> As someone that hasn't used KiCad yet, but expects to soon, my
>> comment is "excellent" :)
>>
>> I have three peeves about many schematics that I see:
>>    - principal signal flow in any random direction
>>    - if a wire leaves one schematic, it isn't clear which
>>      other schematic(s) is reappears on
>>    - signal/bus wires that are named but not visually connected
>>
>> The latter really pisses me off, since on a PDF I have to
>> use ctrl-f to understand connectivity, and the schematic cannot
>> be usefully printed out.
>>
>> No, it isn't merely modern diagrams that do that, you also
>> find it in old Tek schematics.
>>
> 
> I hate hierarchicals and busses and any abstraction that hides what's
> actually on the board. I do everything flat... currently a 31-page
> schematic with five basically identical output channels, each on its
> own sheet. I know exactly where R114 is.

Yes, but what if you are presented with someone else's
schematic like that, and you need to find /all/ the
components connected to R114.

Finding your way around your own schematics is comparatively
easy and reliable.

On Wednesday, June 3, 2020 at 5:34:28 PM UTC+10, Ricketty C wrote:
> I guess I spoke too soon about KiCad being easy to pick up... well it isn't about picking up really.  It's about issues of multiple pages.  They don't really support a flat, multi-page schematic.  It must be hierarchical.  So to have a two page schematic, you must have a top sheet and one or more lower sheets.  
> 
> The parts can have multiple units, but schematics can't have multiple pages.  That seems oddly inconsistent. 

Not really. The trouble with displays is that you can really only see one page at a time in enough detail to make it useful, so you really need a hierachy to provide a structure that you can wander around. Wandering from one page to the next in a flat structure is a situation where you can easily get yourself lost.

-- 
Bill Sloman, Sydney

On 03/06/20 08:34, Ricketty C wrote:
> I guess I spoke too soon about KiCad being easy to pick up... well it isn't
> about picking up really.  It's about issues of multiple pages.  They don't
> really support a flat, multi-page schematic.  It must be hierarchical.  So to
> have a two page schematic, you must have a top sheet and one or more lower
> sheets.
> 
> The parts can have multiple units, but schematics can't have multiple pages.
> That seems oddly inconsistent.

Another viewpoint is to consider the analogous situation in
large-scale software systems.

For one person developing a small piece of code, nothing much
is needed.

But in a large system that requires modification over the years,
it has been found necessary to develop techniques that have
the same characteristics as hierarchical hardware schematics.

Example 1: all the various UML structural component diagrams.

Example 2: the currently fashionable "inversion of control"
techniques. If you sit down and think about what they are
attempting to rectify, and how they are doing it, then you
see they are connecting stand-alone components and sub-components
in a hierarchy.

On Wednesday, June 3, 2020 at 10:18:53 PM UTC+10, jla...@highlandsniptechnology.com wrote:
> On Wed, 3 Jun 2020 10:36:07 +0100, Tom Gardner
> <spamjunk@blueyonder.co.uk> wrote:
> 
> >On 03/06/20 08:34, Ricketty C wrote:
> >> I guess I spoke too soon about KiCad being easy to pick up... well it isn't
> >> about picking up really.  It's about issues of multiple pages.  They don't
> >> really support a flat, multi-page schematic.  It must be hierarchical.  So to
> >> have a two page schematic, you must have a top sheet and one or more lower
> >> sheets.
> >
> >As someone that hasn't used KiCad yet, but expects to soon, my
> >comment is "excellent" :)
> >
> >I have three peeves about many schematics that I see:
> >   - principal signal flow in any random direction
> >   - if a wire leaves one schematic, it isn't clear which
> >     other schematic(s) is reappears on
> >   - signal/bus wires that are named but not visually connected
> >
> >The latter really pisses me off, since on a PDF I have to
> >use ctrl-f to understand connectivity, and the schematic cannot
> >be usefully printed out.
> >
> >No, it isn't merely modern diagrams that do that, you also
> >find it in old Tek schematics.
> >
> 
> I hate hierarchicals and busses and any abstraction that hides what's
> actually on the board.

Of course you do. You don't do anything complicated, where the abstractions are required to keep the over-all circuit manageable and comprehensible.

> I do everything flat... currently a 31-page
> schematic with five basically identical output channels, each on its
> own sheet. I know exactly where R114 is.

But you'd start to run out of puff when you needed to find R501.

I once spent a happy couple of days finding a bunch of missing and duplicated terminal resistors on a triple-extend Eurocard which was mostly 100k ECL.

It had been laid out by sub-contractors who were pretty good, but the project manager had committed to an unrealistic project schedule, and panicked, and got them to send the layout off to the printed circuit shop before it had been properly checked or design-reviewed.

The layout came back from the printed circuit shop with a lot of queries and I got stuck with sorting them out - nobody else in-house knew enough about the board to do it - and it did take a while.

By the time we'd got the board made we were able to get hold of faster ECL-RAM in surface mount packages, and promptly redesigned the board to make it faster, simpler and cheaper - not what you want to do when developing at prototype from scratch, but in this case it was worth it.
 
> I do start a schematic with sheet 1 being the block diagram and sheet
> list/table of contents. Sheets have both numbers and names in the PADS
> pulldown menu.
> 
> The old Tek and HP schematics just sort of suggested where an offpage
> signal went. There was no formal concept of a net name.
> 
> Some schematic editors are just plain ugly. The old ORCAD was ghastly,
> and dangerous.

I used Orcad in 1991-93 in Cambridge for schematic capture and it wasn't too bad. When I moved to the Nijmegen University science workshop in 1993 we had a slightly later version of Orcad,and that worked too.  Just before I moved on the workshop switched to an even later version and added the Orcad printed circuit layout program, which was diabolical. 

The circuits I was working on were big, and the schematics had been made by copying  and repeating large chunks, then relabelling the bus connections, using the old Orcad. We could switch the schematics to the new layout easily enough but to get the layout program to work we'd have had to add the footprints and a bunch of other detail to each of the new pages, before it would even try to auto-route it, and it didn't offer manual routing at all.

After I'd left Orcad had reacted to a lot of user pressure by letting the layout person add the detail manually as the board was being laid out, but the first version had been automatic only.

-- 
Bill Sloman, Sydney

On Wed, 3 Jun 2020 14:14:03 +0100, Tom Gardner
<spamjunk@blueyonder.co.uk> wrote:

>On 03/06/20 13:18, jlarkin@highlandsniptechnology.com wrote:
>> On Wed, 3 Jun 2020 10:36:07 +0100, Tom Gardner
>> <spamjunk@blueyonder.co.uk> wrote:
>> 
>>> On 03/06/20 08:34, Ricketty C wrote:
>>>> I guess I spoke too soon about KiCad being easy to pick up... well it isn't
>>>> about picking up really.  It's about issues of multiple pages.  They don't
>>>> really support a flat, multi-page schematic.  It must be hierarchical.  So to
>>>> have a two page schematic, you must have a top sheet and one or more lower
>>>> sheets.
>>>
>>> As someone that hasn't used KiCad yet, but expects to soon, my
>>> comment is "excellent" :)
>>>
>>> I have three peeves about many schematics that I see:
>>>    - principal signal flow in any random direction
>>>    - if a wire leaves one schematic, it isn't clear which
>>>      other schematic(s) is reappears on
>>>    - signal/bus wires that are named but not visually connected
>>>
>>> The latter really pisses me off, since on a PDF I have to
>>> use ctrl-f to understand connectivity, and the schematic cannot
>>> be usefully printed out.
>>>
>>> No, it isn't merely modern diagrams that do that, you also
>>> find it in old Tek schematics.
>>>
>> 
>> I hate hierarchicals and busses and any abstraction that hides what's
>> actually on the board. I do everything flat... currently a 31-page
>> schematic with five basically identical output channels, each on its
>> own sheet. I know exactly where R114 is.
>
>Yes, but what if you are presented with someone else's
>schematic like that, and you need to find /all/ the
>components connected to R114.

I click a pin and the project explorer shows me the net name and all
the connections. I click one of them and it jumps there.

A heirarichal schematic is worse!

>
>Finding your way around your own schematics is comparatively
>easy and reliable.

I've drawn thousands of schematics. I can't remember them all. With
decent discipline and good tools, I don't have to.

I can open and work on a PADS schematic or PCB that we did 25 years
ago.



-- 

John Larkin         Highland Technology, Inc

Science teaches us to doubt.

  Claude Bernard
  

On Wed, 3 Jun 2020 15:21:21 +0100, Tom Gardner
<spamjunk@blueyonder.co.uk> wrote:

>On 03/06/20 08:34, Ricketty C wrote:
>> I guess I spoke too soon about KiCad being easy to pick up... well it isn't
>> about picking up really.  It's about issues of multiple pages.  They don't
>> really support a flat, multi-page schematic.  It must be hierarchical.  So to
>> have a two page schematic, you must have a top sheet and one or more lower
>> sheets.
>> 
>> The parts can have multiple units, but schematics can't have multiple pages.
>> That seems oddly inconsistent.
>
>Another viewpoint is to consider the analogous situation in
>large-scale software systems.
>
>For one person developing a small piece of code, nothing much
>is needed.
>
>But in a large system that requires modification over the years,
>it has been found necessary to develop techniques that have
>the same characteristics as hierarchical hardware schematics.
>
>Example 1: all the various UML structural component diagrams.
>
>Example 2: the currently fashionable "inversion of control"
>techniques. If you sit down and think about what they are
>attempting to rectify, and how they are doing it, then you
>see they are connecting stand-alone components and sub-components
>in a hierarchy.

A PCB is very different from code. Multiple copies have to be
assembled my manufacturing, from purchased or fabricated parts. Each
board needs to be inspected and tested. If changes must be made, they
will be applied, per an ECO, to every board, by manufacturing.

Field changes are physical and expensive.

A computer program doesn't need many identical copies of a subroutine.
A circuit board often does, but they usually wind up be not quite
exactly identical. They are certainly physically distinct, even if
they look alike on paper.

Computer programs don't need ground or power planes. They should have
test points and BIST, but they seldom do.

Very different.





-- 

John Larkin         Highland Technology, Inc

Science teaches us to doubt.

  Claude Bernard
  

On 03/06/20 16:41, jlarkin@highlandsniptechnology.com wrote:
> On Wed, 3 Jun 2020 14:14:03 +0100, Tom Gardner
> <spamjunk@blueyonder.co.uk> wrote:
> 
>> On 03/06/20 13:18, jlarkin@highlandsniptechnology.com wrote:
>>> On Wed, 3 Jun 2020 10:36:07 +0100, Tom Gardner
>>> <spamjunk@blueyonder.co.uk> wrote:
>>>
>>>> On 03/06/20 08:34, Ricketty C wrote:
>>>>> I guess I spoke too soon about KiCad being easy to pick up... well it isn't
>>>>> about picking up really.  It's about issues of multiple pages.  They don't
>>>>> really support a flat, multi-page schematic.  It must be hierarchical.  So to
>>>>> have a two page schematic, you must have a top sheet and one or more lower
>>>>> sheets.
>>>>
>>>> As someone that hasn't used KiCad yet, but expects to soon, my
>>>> comment is "excellent" :)
>>>>
>>>> I have three peeves about many schematics that I see:
>>>>     - principal signal flow in any random direction
>>>>     - if a wire leaves one schematic, it isn't clear which
>>>>       other schematic(s) is reappears on
>>>>     - signal/bus wires that are named but not visually connected
>>>>
>>>> The latter really pisses me off, since on a PDF I have to
>>>> use ctrl-f to understand connectivity, and the schematic cannot
>>>> be usefully printed out.
>>>>
>>>> No, it isn't merely modern diagrams that do that, you also
>>>> find it in old Tek schematics.
>>>>
>>>
>>> I hate hierarchicals and busses and any abstraction that hides what's
>>> actually on the board. I do everything flat... currently a 31-page
>>> schematic with five basically identical output channels, each on its
>>> own sheet. I know exactly where R114 is.
>>
>> Yes, but what if you are presented with someone else's
>> schematic like that, and you need to find /all/ the
>> components connected to R114.
> 
> I click a pin and the project explorer shows me the net name and all
> the connections. I click one of them and it jumps there.
> 
> A heirarichal schematic is worse!

Fine for the author. What about a customer (or other) that
doesn't have access to your schematic program?


>> Finding your way around your own schematics is comparatively
>> easy and reliable.
> 
> I've drawn thousands of schematics. I can't remember them all. With
> decent discipline and good tools, I don't have to.
> 
> I can open and work on a PADS schematic or PCB that we did 25 years
> ago.

Fine, apart from the above caveat.
What about in another 25 years?

I'll bet PDFs and dead trees will still be readable then.