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#1 Sinphaltimus OFFLINE  

Sinphaltimus

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Posted Sun Jul 9, 2017 4:32 PM

I'm attempting to use KiCad after a lot of recommendations from various sources. I'm a complete noon and very much confused at the moment but I was able to start using the schematic designer to recreate my 4 port cartridge expander design.

Had a hard time finding some symbols, namely and regular single throw 2 pole switch and the US standard of a resistor. Google and reading a lot helped me find those two things.

Problem is, when I load them in to my schematic, they are huge and too big for me to use which tells me I started the schematic wrong.

How do you do things like a GROM port connector (not the connector itself but just the holes to insert a connector) with proper spacing for the holes and such. do I have to physically measure these components then try somehow to replicate that in the software?

I want it to take the standard GROM port 90 degree angle connector (with the grom port removed) to interface with the TI console's cart port. do I need to measure and replicate the pin holes the same way?

I simply don't know enough about through hole connections and measurements and spacing and such. How can I adjust the snap grid etc..?

so before I go crazy redoing this schematic like 50 times before I get it right, what do you all recommend?

Here's a screenshot - 

Attached File  kicad.png   102.36KB   0 downloads



#2 Gip-Gip OFFLINE  

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Posted Sun Jul 9, 2017 4:55 PM

Schematics aren't for PCB layout, rather to get the idea of the circuit across.



#3 Gip-Gip OFFLINE  

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Posted Sun Jul 9, 2017 4:56 PM

And I'm pretty sure there's a generic device you can use in place of the GROM if it comes down to it



#4 matthew180 OFFLINE  

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Posted Sun Jul 9, 2017 5:03 PM

Schematic capture (drawing schematics with software) and PCB layout are non-trivial and require a certain amount of dedication to learning the basics.

 

Typically you start with a schematic so the software can help you make sure the PCB is correct.  You *can* go to the PCB layout and just start drawing traces and such, but that is very error prone and a lot harder IMO (although some people do exactly that).

 

Probably one of the hardest parts of schematic capture and PCB design is getting the components you want to use into the software.  A component usually consists of two main "parts", one is the symbol and pin detail used in the schematic.  The other is the footprint used by the PCB layout, which is the exact size and shape of the holes or pads that the part will be soldered to.

 

Many EDA (electronic design automation) software come with hundreds of thousands of components with symbols and footprints ready to go.  However, no matter how many parts a software claims to have in their libraries, I find that many of the parts I need are not available.  In that case, most software will provide you the tools to make your own components, i.e. draw the symbol, specify the pins, draw the footprint, and associate the symbol the the footprint.  You get the component details for the manufacturer datasheet, which will include the physical dimensions for the footprint pads, holes, spacing, thermal requirements, etc.

 

You will find that chips, edge connectors, etc. are almost always based on standard sizing, i.e. through-hole DIP chips will have a 0.1" pin spacing, same with standard headers, etc.  Surface mount components are usually metric and have a 1.0mm pin spacing, or 0.5mm for fine-pitch parts, etc.  Again, check the datasheet.

 

For the board-edge connections on the 99/4A, you are looking at 0.1" spacing, but you need to check the datasheet of the edge-connectors for recommended widths of the copper edge-pins.

 

I don't recommend KiCAD for a beginner.  Yes it is open-source, but how tall and thick of a brick wall do you want to beat your head against?  If you plan to make your design open source itself, then go with something like CircuitMaker or EagleCAD hobby version (both free).  CircuitMaker is the free version of industry-leading EDA software publisher Altium, and is pretty awesome IMO, especially the routing features.  This is *NOT* a stripped down version of their flagship software.  You get full access to the software as long as you are willing to keep your designs open source.

 

Oh, and don't auto-route.  Manually routing a PCB is not that hard, however, making a good (and working) PCB is an art as much as science.

 

Plan to spend some time learning the lingo and basics.  Find some tutorials and follow them to get and understanding of what all the parts are and how everything fits together.  There are video tutorials for both CircuitMaker and EagleCAD for beginners that take you through the whole process.



#5 Gip-Gip OFFLINE  

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Posted Sun Jul 9, 2017 5:10 PM

how tall and thick of a brick wall do you want to beat your head against?

 

If I'd have to say anything KiCad isn't much harder than the other programs, just gotta get used to the "controls" per-se and you're all good. I started about a month ago and it was no problem for me.

 

(I wouldn't take my advice as I'm somewhat experienced in CAD and I had no other good options with linux)



#6 Sinphaltimus OFFLINE  

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Posted Sun Jul 9, 2017 5:13 PM

Thank you for all that. My actual PCB design would be super simple. Nothing more than switches and resistors. It's the GROM port connections that are my main concern and I definitely will do more research and learning.

Here's a schematic I did in DIA but I want the new schematic to represent the actual design more (horizontal instead of vertical). I suppose I'll need to measure the distance between GROM ports as well to keep 'em as tight as possible so 4 carts are barely touching if at all. I want to use this PCB to replace all those wires and connectors in my non-working prototype. Drop in the grom ports, GROM port connector, resistors and wire up any switch(es). 

 

EDIT: Just so you have an idea of my task.

Attached File  Diagram6.png   421.54KB   0 downloads


Edited by Sinphaltimus, Sun Jul 9, 2017 5:13 PM.


#7 Gip-Gip OFFLINE  

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Posted Sun Jul 9, 2017 5:18 PM

Thank you for all that. My actual PCB design would be super simple. Nothing more than switches and resistors. It's the GROM port connections that are my main concern and I definitely will do more research and learning.

Here's a schematic I did in DIA but I want the new schematic to represent the actual design more (horizontal instead of vertical). I suppose I'll need to measure the distance between GROM ports as well to keep 'em as tight as possible so 4 carts are barely touching if at all. I want to use this PCB to replace all those wires and connectors in my non-working prototype. Drop in the grom ports, GROM port connector, resistors and wire up any switch(es). 

 

EDIT: Just so you have an idea of my task.

attachicon.gifDiagram6.png

I'm interested in why you want to make the Schematic dimensionally accurate. Or at least, that's what I'm getting from you.

 

Also, have you looked at the GROM's datasheet (if there is one)? They usually come with dimensions 



#8 matthew180 OFFLINE  

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Posted Sun Jul 9, 2017 5:40 PM

Use "named-nets" and drop all the lines (called "nets") in the schematic.  It is too error-prone  You don't need to actually draw the lines to make the connections.  If you give two nets the same name, the software will connect them logically.  If you like seeing lines, then consider using buses.  Maybe draw lines for the individual unique signals.

 

@Gip-Gip: I'm sure there are EDA options for *nix other than KiCAD.

 

I tried KiCAD a while back when I was trying to setting on an EDA, and I just found it frustrating.  Now, that was before CERN decided to use KiCAD internally and contribute to the software, so maybe it has come a long way in the last year?



#9 jedimatt42 OFFLINE  

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Posted Tue Jul 11, 2017 12:18 PM

Cern has made lots of improvements. It frustrated the heck out of me compared to Robot Room Copper Connection, until I made myself follow the workflows in the tutorials.

For a picture of my TIPI schematic and how much it differs from the board layout, take a look on github.com/Jedimatt42/tipi, in the tipi kicad drawer I have a schematic.pdf and a pcboard.pdf.

This labelled net style will be a lot easier as you'll be able to copy your switch and cartridge port assembly with the labels and they will all be wired to each other.

Once you embrace the component editors Kicad gets a lot easier.

Once the schematic has the components on it, and the electrical network defined either through wires or labels you save the netlist. Kicad is a set of tools that interoperate around the netlist file. So you save the netlist. Then open the tool to associate footprints (hiw the component looks on the pcboard) to each component in the netlist.

Then save that, resave the netlist from the schematic (that step seems like a bug) , then open the pcboard editor and import the netlist.

It will stack all your components in the middle. So you grab each and spread them out. You'll see the required electrical connections shown as a spider web that then clears as you lay down traces to establish the connection.

The push and shove router is nice. You have to be opengl mode from the view menu. And you have to go into the routing preferences to turn it on.

I've watched TerribleFire on YouTube doing his Amiga accelerator design work in Eagle, it looks better, but once you get the workflow in Kicad, it isn't bad for free.

-M@

#10 Sinphaltimus OFFLINE  

Sinphaltimus

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Posted Tue Jul 11, 2017 12:29 PM

I don't even need components really, just the through holes where components will go. In my head, it's such a simple 2-layer design (can probably done single with proper routing) with nothing more than holes and traces. I understand these software packages can design vastly complicated components, but my project isn't one of them. so many things happening right now - literally have to do house work (moving things into attic), My new vampire Accelerator for my Amiga arrive 3 weeks earlier than expected, I have 2 GamePads to mod for someone, and my basement is a cyclone disaster area with 13 years of computer component collection needing to be organized and put away before the second week in August. Oh woe is me LOL. And now I have this PCB design stuff hanging over me like a dark cloud because my cartridge port switcher project should have been completed and working BEFORE FestWest and then I want to make a v2 of my musick program that will utilize the 6 button gamepad as an interface for effects, and ZOMBI, lest we forget ZOMBI, oh heck no.  It's all fun and games racing against the clock. LOL :) And that's not to mention a Computer Science course i purchased that I am dying to continue. SQL is boring but it's chapter 1 and I really want to learn it. *sigh* - well that's that. I was under the impression I could have had this PCB done in a couple of hours but only if I knew what I was doing.



#11 matthew180 OFFLINE  

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Posted Tue Jul 11, 2017 3:09 PM

You should still make components (symbols for the schematic and footprints for the PCB.)  The complexity of a chip has nothing to do with the footprint.  A DIP-16 is a DIP-16 no matter what the chip does.  You have parts that will go in holes that need to be of a certain diameter and have specific spacing, etc.  You want to be able to move those holes around in the PCB editor as a unit, so make a footprint.  Like I said earlier, there is a learning curve that you need to be prepared for.  Trying to go quick and cut corners will only result in time wasted and frustration.

 

Circuit boards *always* seem like they should be quick and easy, but they never are.  However, the more you do the faster you will become.  But that is the problem with hobby work, you tend to get intense on something for a period of time, then let it go for a while and forget all the details about things like PCB layout.  So it always takes more time than you want to get back into it.  People who do PCB layout for a living could probably crank your board out in an hour.  So pay them if you don't have time.  But as hobbyists we typically have more time than money, or prefer to learn and do the work ourselves.

 

Power supplies are another one of those things that you think should be easy but really are not.  One of the hardest parts of doing the F18A was designing the power subsystem.

 

Make components for your edge connector(s) and for your switches.  You will be glad you did.  Use net names to make connections, and standard library components for anything else like resistors, capacitors, diodes, etc.  Those kinds of parts should already be available.






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