Amiga 600 schematics nearly put into Kicad

[dashie]

Originally Posted by Mick

When you say freerouting in layour editor has that been dropped in recent version of Kicad? when I tried autorouting before I was directed to some separate java app.

Is your 2000 PCB fully working? you should make a thread it's awesome.

I was using the java version from LayoutEditor (it's a separate project from KiCAD), AFAIK KiCAD doesn't have a full autorouter builtin.


I can boot a workbench and it pass diagrom, but I have lot of stability issues when using an accelerator, I think it might be noise issues, but didn't had time to dig more.

[Mick]

Ah ok, if I recall correctly they are having similar problems on A1K. I think someone mentioned that the A2000 was a notoriously noisy design.

I just have the keyboard/PCMCIA and few other bits to do tomorrow and then I'll re-upload and people can try to find mistakes and take over for the layout I guess. I can't see myself being able to do that.

[Mick]

I've uploaded my latest progress. I found quite a few errors with global labelling and missing underscores etc. I've also fixed most of the inputs/outputs, changed a couple of bus labels for Kicad and disabled NC pins.

The good news is warnings are down to less than 40, the bad news is there are 2 errors relating to interrupts which I can't figure out. Any ideas?

EDIT: It's the end of the road for me I think so I've uploaded the final draft, I've done all the proper capacitor/resistor sizes although replaced electrolytes with through-hole. It needs a few custom footprints, probably some error checking and then all laying out. Hopefully someone can do something with it as I've spent days putting this together. All that I ask is if you do use it and create something please share with the rest of the community.

I think part of the power circuitry could be removed as it relates to the old video DAC with the external delay lines and filters? the mono output could be removed as it was for RF. S-Video output could be added. It's too technical for me though.

[Mick]

I've made some footprints for the keyboard and power connector and although I keep getting urges to try to lay it all out I'm basically at the point where short of someone sending a faulty/fully desoldered PCB I can't even attempt it unless I do it like a game of pin the tail on the donkey.

[Stedy]

Originally Posted by Mick

I've made some footprints for the keyboard and power connector and although I keep getting urges to try to lay it all out I'm basically at the point where short of someone sending a faulty/fully desoldered PCB I can't even attempt it unless I do it like a game of pin the tail on the donkey.

Mick,

https://www.amigapcb.org/

Tempted now?

[Mick]

I've actually been using that site to check things but it doesn't appear to be 1:1 scale? it just scales to my monitor. If I could get something like that in exact scale it would be ideal.

Does anyone know the overall length/width of an A600 motherboard? maybe if I shop it to the right size it will be in ratio.

Also, there's still a few things with Kicad that are baffling me:

1> Ferrite beads seem to be blocking voltage which is kicking up warnings in error checker.
2> VCC & GND labels aren't showing in PCBNew, what I'm seeing instead is U12_1 and U13_1 which are global labels I made for two of the symbols.

[Mick]

I hope the overall dimensions are accurate. I have a life size printout I've somehow managed to cobble together. It took me about 2 hours to print out an image without it being scaled and now I've got 2 pages cellotaped together.

[dashie]

from my board (rev 1 but 2 should be the same) I have something around ~32cm by 19.5cm, widest dimensions.
more accurately the extension connector is : (left, full width, right): 74mm, 112mm, 37mm, connector is 52x80.5mm

1> Ferrite beads seem to be blocking voltage which is kicking up warnings in error checker.

Add a PWR_FLAG right after the ferrite to the IC.

[Mick]

Thanks dashie. I think I read somewhere that there's a slight size difference between Revision 1 and 2 boards. I've used a screen grab of that Amiga PCB site for dimensions, the pitch of the floppy/ide connectors is spot on and outright board dimension is 317x194mm iirc.

To be honest this is more of a personal challenge I didn't thnk I would get this far, I'm unlikely to finish it without someone helping me with schematics and probably being a guinea pig building one and testing. I'd like to add a s-video header (which the newer videodac supports) and possibly vga connector. I think there's also a bit of the old power circuit that can be removed which was for the old external Z221 filters etc but I dont really understand enough about electronics to do it.

Why does Kicad think that ferrite beads block voltage? don't they just reduce noise? do you know how I can get GND to show as GND and VCC as VCC? at the moment they're showing as U13_1 and U12_1 or something like that in PCBNew and it's really confusing.

[Daedalus]

It doesn't really matter what the part is - the signals either side of the bead are considered two totally different circuits. I would mark the 5V rail after the ferrite bead, since this is the circuit that supplies the chips and not the circuit before it.

[Mick]

Okay then.

The front placement is now finished. I found a few errors with schematics as well they really need looking over by someone clued up on circuits and how Kicad does things. I'm off to watch footy and then I'll try to make a print out of the back.

...

[Mick]

I finally finished the placement front and back. I also found the so obvious I didn't see it flaw in replacing SMD caps with TH on a double sided PCB so SMD caps are back. The only problem is there are two capacitors left over, E131C and E132C which are in the schematics but not anywhere on any board from what I can see? do I add them or remove them from the schematics?

There's still a few holes to do but fixing the schematics is probably more important at this point. I found a few mistakes myself while laying them out.

What sort of circuits do I need for an s-video header and VGA output like Chucky did? oh and does anyone have dimensions for the hard drive caddy holes?

Thanks.

[Heywood]

Hi Mick,

I've been watching your progress with interest as the A600 is kind of my favorite amigas, I'm not particular great at PCB design, nor likely to successfully assemble a SMD PCB, so I hadn't much to offer in advice but I guess one of the things I was wondering (assuming there is interest on your side to consider it) would be whether there would be room to support including a jumper that could be used to swap the internal and external floppy as DF0/DF1 - kind of like what Bryce describes on Amibay? This might be nice in selecting between using a gotek and real floppies in a graceful manner (those that change often could connect a switch to the jumper)

[Mick]

Hi Heywood, if people help anything should be possible, there's more than enough expertise in the Amiga community from what I can see. I'm good with computers (probably down to having an Amiga at such an early age) and picked up Kicad like a duck to water but I just don't really understand the electrical circuit side of things. I'm scared to add or remove anything unless it's spelled out to me like the CXA2075M replacement mod was. I decided to try to lay it all out hoping people would be more inclined to help with the schematical(is that a word?) side of things if they saw it close to completion (assuming I could do it).

I was going to just make all files publically available as I went along but I don't want to release the layout until I know it's fully checked or some chancer will probably stick bug-ridden PCB's that might not even fit the case on Ebay. I've just uploaded the schematics for now for people to check and perhaps help modify but if I can get enough help to finish it and release the full files people can probably add anything they like without spending 2-3 weeks going through what I have been through.

I have to get someone else to build my PCB's as well so once it goes to PCB manufacture stage I'm a bit out of my depth anyway. I figure I can probably buy cheap 2 layer PCB to check physical dimensions first and then get a proper routed one made which either a volunteer would need to test or I would need to pay to get it built with all the parts, I don't even know if the guy who does mine will want to spend his time diagnosing faults.

[dashie]

@Mick does the archive on the Zone is up to date and which issues do you still have with kicad/schematic/pcb ?

It is probably best for a starter to do a ~1:1 and then after it works to start doing mods, might be harder to debug something if it doesn't works properly first.

Also releasing it "not working" or "partially" can permit someone else to work on it instead of restarting from scratch.

[Mick]

I've just uploaded the most up to date schematics about 10 mins ago. I've been finding a few missing junctions but I think that was from when I modified a few of the symbols.

I was wanting to add VGA connector and S-video header to make full use of the video DAC and also the IREF and VREF signals are no longers needed so I wondered if they could be removed easily to clean it up a bit. Other than that just look for and try to find mistakes in the schematics.

I added the newer DAC because from what I've read the delay lines/band pass filter (Zxxx) are dying of old age and they're impossible to now get, the CXA2075 has it all internally.

[Stedy]

Originally Posted by Mick

I've just uploaded the most up to date schematics about 10 mins ago. I've been finding a few missing junctions but I think that was from when I modified a few of the symbols.

I was wanting to add VGA connector and S-video header to make full use of the video DAC and also the IREF and VREF signals are no longers needed so I wondered if they could be removed easily to clean it up a bit. Other than that just look for and try to find mistakes in the schematics.

I added the newer DAC because from what I've read the delay lines/band pass filter (Zxxx) are dying of old age and they're impossible to now get, the CXA2075 has it all internally.

Give me a few days, probably over the weekend and I'll check the schematics in full. I'll take a look at the issues quoted above and check them out, I'm quite good with video circuits Get the basics right, then you can easily add things.

I have a simple scheme to swap DF0:/DF1:, base don the A4000 design that I can share. Currently it's VHDL but easy enough to sketch. I'd recommend a Minimig SCART/VGA connection for video, it removes the need for unobtainium 23 way d-types!

I have the schematics loaded in Kicad so will get busy.

Ian

[Mick]

Hi Stedy, thanks.

There's been a slight change of plan though I just want to know how to make full use of the CXA2075 now (s-video header and maybe 10 pin header for VGA cable?). I thought about it last night and rather than try to remove stuff without breaking anything, I thought it might be better to throw in the kitchen sink and add the newer DAC on a different footprint with only what it needs. I have come up with this:




You can use either DAC's, so the board is 100% fully backward compatible for transferring old parts but also has option to use the newer DAC without the impossible to find Z221/Z222.

There are 2 extra resistors on the back for CXA2075, one is for the trap thing and the other to pass audio to the RF when using the newer DAC which doesn't have audio in/out. I'm quite proud.

If I can get help adding the s-video/vga portion that would be great but room is at a premium if it's going to need lots of extra bits or will affect the CXA1145 so I might have to leave it as it is? I will release all files eventually but I'd like to check dimensions on a physical board first?!

edit: thinking about it would a vga header work with the CXA1145 as well?

[kipper2k]

Great work Mick,

As an opportunity exists to mabbe do some updates. If you could make a header to capture all the CPU signals that would be awesome, it will open up the A600 to a lot of updates. It could be in the form of 2 x 32pin 1mm FFC headers or something similar that doesn't need too much space. I would make something to take advantage of this

[Mick]

If you list the exact signals I will as they won't really impact anything but I don't want to clutter it with all kinds of mods for now, I'm going to release the files so people will be able to mod it until their heart is content. I just would like to check for any embarrassing stuff like holes out of line first.

Actually, one thing I wondered about kipper is what are you using for the A500 keyboard controller on your MX keyboards and could it be used in the A600? the reason I am asking is I've looked around for the A600 keyboard chip and they are nowhere to be found.