Any libraries for the W65C816 processor?

Are there any libraries out there that add schematic symbols for the 65816 processor? If so, where can I find them?

Often, googling for “kicad xxx” is a way to find KiCad parts.

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There are some 3’rd parties that make them up for you. This one looks kinda simple but something like this might help simplify it further.

The reality is you may as well learn to make the symbol for this one because it will teach you to rearrange pins at the same time. This will probably make your schematic much nicer in the long run. In fact in this case if you add the pins as you use them you might find it easier.

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Thanks for the information. I literally just downloaded KiCad today and I’m new to CAD software in general, so it didn’t occur to me that It would be better to learn how to make the symbol myself.

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Google isn’t always helpful though. I just searched and I couldn’t find anything (though oddly enough, this thread was first in the search results)

With millions of electronic components currently in production it is impractical to supply schematic symbols for all of them. Regardless of whether you use KiCAD or some other program for schematic capture (including the “Big Names” who charge Big Buck$$ for their software) you will spend a significant amount of your total project time doing “library work” - creating symbols, footprints, or templates. At this point in your learning this seems like an unproductive diversion from your primary goal, and it probably is. However, it’s a skill you will have to master before you can honestly claim to be proficient with your schematic capture and layout software.

@AshtonSnapp, Welcome to KiCAD and welcome to this Forum. Almost everybody here is a KiCAD user who walked the path you’re on at some time in our lives.



Yeah, in general I agree but there are just enough pins on this thing to make for an ugly schematic so rearranging pins will be needed. I don’t think this is too far from just adding the pins as needed to a rectangle.

OP. Probably not a new series with Kicad 5 yet but check out “getting to blinky”. You should find it in the FAQ index which can be accessed by using the link in the top bar. A little prep will save a lot of aggravation

Understandable. Though it is very frustrating to make the library for this part, as all the datasheets and electronics retailer (read: Mouser) listings don’t give the chip’s dimensions. Not to mention that haven’t actually purchased any parts (since I’m still working everything out), so I can’t exactly measure it myself.

Also, @hermit, I can understand why I’d have to rearrange the pins. For some reason, they decided to arrange the pins so four of the pins on the address bus are on the other side of the chip. It’s not even in sequence, since they put VSS/ground on pin 20. And the data bus pins also double as memory bank pins. Why did they design this chip like this???

It must be some standard packages which already have footprint in the KiCad libraries. But you still need to know the dimensions and some other specifics, there are too many options for a beginner. E.g. DIP-40, the most probable candidate, has 12 options.

I can only guess. Maybe it lays out on the die nicely. Maybe the original chip was designed with a specific customer usage in mind. I did a quick check of the data sheet and this has a couple footprints available. One is a DIP. Dual inline package. The other footprint for surface mount looked to be standard also but I didn’t go too far. Once you have the symbol you can probably just assign it to a standard package.

For the schematic library, you really don’t need the actual dimensions. I checked the Mouser datasheet, and it does tell you on pages 12 and 13, but one would need experience to understand what they mean. There are three packages; a 40 pin DIP, a 44 pin PLCC, and a 44 pin QFP. Those names “DIP”, “PLCC”, and “QFP” are common generic package names. Also, note that each of the packages have different pinouts. You should know which package you plan on using before designing your schematic symbol (probably best to have a symbol with multiple parts, otherwise this would be a very large symbol). Looking at the last page of the datasheet, Mouser only provides two links, the 40DIP and the 44QFP so the PLCC might not be available from them.

I agree that it is poor documentation to not specifically give the information on the website, but on the second to last page of the mouser datasheet (I think it is the actual last page of the original datasheet, looks like Mouser added that last page) is a link to the manufacturer’s web page where you may find more detailed information.

As I mentioned in my message, each of the 3 packages have different pinouts. The OP should decide on a package to use first.

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I had already decided to use the 40-pin DIP package. I don’t know how that’s supposed to tell me the dimensions of the chip however.

OK. I looked at the datasheet. My question is WHY are you using this chip. If the documentation is so poor that they can’t specify suggested footprints I’d be worried about lots of other things. Unless pdip40 is only ONE width?

This is where experience comes in. I will attempt to share some of mine for you.

DIPs (Dual Inline Package) are almost always 0.1" pin spacing on the two sides. At the 40 pin count they will usually have 0.6" between the two rows of pins. Since Mouser calls the package for the 40 pin DIP a “PDIP40” (the “P” just indicates the body is plastic, there are also CDIPs that have ceramic bodies.) I would call the 0.6" width a good bet. (There are 1.0" width between rows, but they are much rarer, and would have a modifier to the package name.)

Looking in the KiCAD standard library “Package_DIP” I see several that start with DIP-40. If we assume the 0.6" width, we can narrow down the choices to only the ones that next say “W15.24mm”. The footprints that end with the word “LongPads” are designed with oval pads to make it easier to hand solder. The footprints with the word “Socket” appear to have the same pad and drill sizes as the corresponding footprints not marked socket, but the silkscreen (and courtyard) is a little larger to encompass the pins. This is because IC socket bodies cover pins, where an IC body is totally between the pins. I suspect you aren’t going to use a surface mount socket to connect the IC, so you can probably ignore the footprints that say “SMDSocket”.

Personally, I’d probably socket the chip to allow you to pull it out for re-programming, or have a couple with different programs installed for swapping in the field. So this is probably the footprint that I would use:

If you find that these parts actually are 1.0" width, then select the corresponding footprint with “W25.4mm” as the name.

But, really, you shouldn’t really need the package size until you are ready to start assigning footprints. You may choose to assign the footprint now when you are just starting to capture the schematic. But, you only need to have all the footprints picked and assigned when you are ready to start laying out the PCB.


Here’s what happened in my head as I read this:

  1. I am way in over my head
  2. I’m guessing y’all thought it was a micro-controller (it’s a processor)
  3. Sockets make life easier.
  4. I read this right after I finished making my own symbol for this thing :sweat_smile: (and I just realized you were talking about the Footprint library, not the Schematic Symbol library. My hard work is not wasted!)
  5. @hermit I’m using this chip because it developed from the processors used in computers from before I was born. And also, I’m guessing they didn’t specify footprints because either they thought people who were going to use it would just “know” the dimensions from looking at the package, or they hoped people would call them for extra information so they could sell more stuff.

That is odd, because the first 3 results I get are links to libraries for KiCad.

This is what appeared whenever I looked it up. Though, this might be due to the search engine I'm using (which I included in the screen snip)

Yeah, don’t worry. We all were at one point. I hope my messages weren’t taken as condescending. My intent is to be helpful.

Yeah, they are different, but for the help you needed it really doesn’t matter.

Yep. I agree as long as the added cost isn’t an issue. Or, unless the project is going into a vibration heavy environment. Also make it easier to change blown chips. :wink:

Sorry, I should have put my last paragraph first. :slight_smile: Make sure you double check that you used the correct pin assignments. (I find if I don’t double or triple check, I get something wrong.)

Also, since you are new to KiCad and ECad in general, look through the FAQ here. One of interest (before you start getting seemingly inscrutable errors with ERC) is this one about pin types when designing schematic symbols:

Good luck on your project, and please feel free to ask questions. As with any forum, the better the question the better the answers. :yum:

Since the W65C816 is a 6502-family processor, you may also wish to visit There are several people on that forum with very deep knowledge of the 6502 and its derivatives.