Sporniket's log on hardware stuff

[sporniket]

Just a little post to share the gerber of my custom breadboard-style protoboard that I use to assemble my build of the gbscontrol mod, in the hope that someone will find it useful ?

sporny-proto-board--21.01.00.zip

sporny-protoboard-00.jpg

At first it was designed to accommodate the width of the nodemcu, what traditional protoboards I had could not do, and it was also a first try with kicad and jlcpcb.

sporny-protoboard-01-compare-with-classical-protoboard.jpg

The underlying idea is the collation of 2 half-size breadboard, each half has a power supply rail set (Vcc/ground), that can be common to the whole board thanks to a jumper.

Another feature is that it is just under 10cm×10cm to fall under the threshold of jlcpcb.

Finally, there are M2 mounting holes on each corner that may safely be enlarged to M3 size.

[sporniket]

These days I went back to my project of converting the barely readable scans of Atari STE schematics into Kicad. The principles that I want to follows are more strengthened and are as follow :

• Use A4 sized, portrait oriented sheets –I wanted to go down to A5 to get easily readable, zoomed sheets printed on A4, but the GSTMCU will be too much–
• One hierarchical sheet per original sheet, then each one is subdivided into hierarchical sheets again, one per big IC, or pair of IC in some special cases (e.g. eproms)
• Use the physical layout of the pins in IC symbols, to help newbies like myself to pinpoint more easily where to put a probe, hopefully.
• Limited use of wires, essentially to allow net highligthing.
• Use original label names and component annotations, for easier proofreading/cross-checking.

So far I am dealing with the first sheet, and I can show some subsheets as proof of concept.

subsheet_100-Sheet 1 of 6-U100 - MC68000.pdf

subsheet_101-Sheet 1 of 6-U101 -- Blitter.pdf

subsheet_102-Sheet 1 of 6-U102-U103 -- EEPROMs.pdf

subsheet_104-Sheet 1 of 6-U104 -- Reset circuit.pdf

I'm open to tips and suggestions, and if you spot errors in my conversion, I would be happy to fix them.

[sporniket]

The first sheet is almost done, here are the power connector and the cartridge port.

The 32MHz signal generation is almost captured, the PAL reminds me that beyond basic circuitry, "I have no idea what I'm doing !" :lol:

subsheet_103-Sheet 1 of 6-J103 -- Cartridge port.pdf

subsheet_105-Sheet 1 of 6-J100 -- Power connector.pdf

[sporniket]

And now the Pal clocks/32Mhz clock.

subsheet_106-Sheet 1 of 6-32 MHz clock and video clocks.pdf

I pushed all my progress so far on my github for this project, so you should be able to browse the Kicad files : https://github.com/sporniket/retro-comp ... matics.git

The Kicad project is the file atari-16-32-bits/motherboards/c300780-001/motherboard.pro

[sporniket]

2021-04-28--01.jpg

Finally got a still working :cheer: lynx 2 for a fair price on the bay. The display is white-ish -too bright-. Voltage at C41 is at 8.5V, so no more powering up until I replace the mosfet Q12 and the Zener diode.

Other than that, it powers-on as soon as batteries are installed and the power-off button does not work (that was stated on the description) and there is a suspicious bodge wire between the battery+ and the power supply plug (a little bit sloppy as the battery may be shorted by a component of the wire used).

2021-04-28--02.jpg

All i all, just a little bit of work. Then I plan to replace the screen with one made by Ben, and have a RetroHQ Lynx GameDrive, in whatever order.

[sporniket]

I started to convert into Kicad the sheet #2 of the Atari STE schematic.

subsheet_200-U200 — Acia 1 to MIDI IO.pdf

I had to create a symbol for the "T Filters", I just duplicate the European symbol of a resistor, with the annotation inside, like the original schematics. I was puzzled because when I look for T filters, I would require another pin ? Anyway for now, I stick to the source schematic.

Also, like in the schematics of the PAL subcarrier/32MHz, I have to arbitrate between using wire and using net names to link components. And in fact, it goes down to whether I can or want to find a name for a net or not.

The github repository (see my signature) is up to date.

[exxos]

The filters are 3 pin yes.

[sporniket]

The filters are 3 pin yes.

Ok I used the built-in symbol then.

subsheet_200-U200 — Acia 1 to MIDI IO.pdf

[sporniket]

...And I forgot the bypass capacitor...

So another revision of this sheet, and the schematics of the second Acia.

subsheet_200-U200 — Acia 1 to MIDI IO.pdf

subsheet_201-U201 — Acia 2 to IKBD IO.pdf

[sporniket]

This week-end, I converted the schematics of the sound generator and the parallel port.

subsheet_202-U202 — PSG and Parallel IO.pdf

I also posted a video showing the workflow that I follow.