VG8020 keyboard to PS/2 port. Schematics available?

Por AxelStone

Prophet (3046)

Imagen del AxelStone

02-06-2021, 20:38

Hello everyone, I'm thinking about a DIY project to put a Zemmix Neo board inside a VG8020 case. All devices can be put in the corresponding outputs using extensors (joy ports, power button...) and the cartridge slots are in perfect position.

My main question is, what about keyboard? Zemmix Neo uses PS/2 conector so it should need to be adapted, I suposse that using Arduino. Are there schematics available in some web?

Thanks!

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Por andrea.denara

Expert (73)

Imagen del andrea.denara

03-06-2021, 11:16

I've also been looking for a long time for a scheme to build a VG8020 TO USB interface (the Ps2 connection can be done with an adapter).
Several interfaces have been made with the C64 and they work great.
I think it's useful, many have non-working VG8020s and maybe no longer have CRT monitors (like me).
The use of a simple interface would allow to revive these machines

Por andrea.denara

Expert (73)

Imagen del andrea.denara

03-06-2021, 11:23

I think even if I am not very sure (because you have to open the machines) that the keyboard interface can be compatible for different Philips Msx but also with other PCs (see the photos of the keyboards of VG8020, VG8220, VG8245, VG8280 etc)

Por ssfony

Expert (78)

Imagen del ssfony

03-06-2021, 15:28

The keyboards are just key matrixes connected to the PPI. If the PPI is emulated in FPGA, then theoretically you could connect the matrix directly to the FPGA (if it has enough free pins left). KDL or someone else with enough knowledge might be able to adapt the firmware for it.
This would actually be really cool and be perfect emulation Smile

Another option would be to connect the matrix to some adruino type of device... or an actual PS/2 keyboard controller.
Then all you need to do is create the right key conversion map for the fpga.

Por bsittler

Master (245)

Imagen del bsittler

03-06-2021, 18:03

Some of these may help?
https://www.msx.org/forum/msx-talk/hardware/ps2-keyboard-msx...
https://tms9918.hatenablog.com/entry/2014/10/01/233910
https://gist.github.com/tiagosr/6dc470ffc164d240175e
https://msx.gouget.com.br/2014/06/24/ps2-keyboard-to-msx-wit...
https://msx.gouget.com.br/wp-content/uploads/2014/06/Schemat...

(I have been researching in preparation for making an adapter to use a different keyboard on a Gradiente Expert because the original one has problematic mechanisms. I'm hoping to use either the National CF-3000 keyboard or a PS/2 keyboard with it)

Por andrea.denara

Expert (73)

Imagen del andrea.denara

04-06-2021, 07:44

I see a USB interface much more useful, I don't know about you but here in Europe the PS2 interface has practically disappeared and then eventually you can use an adapter.

Think of the ease of use: Do I have an FPGA like the Mister? No problem the USB port is available. Do I have a Raspberry? No problem, the door is available here too.

Example (C64 with cheap Arduino Micro)

Por Danjovic

Master (192)

Imagen del Danjovic

04-06-2021, 08:17

AxelStone wrote:

My main question is, what about keyboard? Zemmix Neo uses PS/2 conector so it should need to be adapted, I suposse that using Arduino. Are there schematics available in some web?
Thanks!

There is an arduino library named ps2dev that is a starting point
I suggest you to read this forum thread here (link)
You'll need at least 20 pins (17 for keyboard matrix plus 1 for caps led plus 2 for ps/2 connection), which means that you will either need to use a glue logic chip to help you ( for instance a LS145) or an Arduino with more pins.