Raspberry @15Khz

[kortina]

Hi Guys,

I know this is not GroovyMAME specific, but thought that many might be interested:


Looks like you can get a 15-Pin 'VGA' connector output for the rPI, and output a 15khz signal from it.

This might make classic gaming a lot more accessible for those who can get their hands on an old CRT TV with a SCART input!

Has anyone tried it?

[elvis]

There's plenty of folks using this (or similar) solutions for 15KHz out to SCART TVs and arcade monitors.

A few points to note:

1) Any analogue solutions using the GPIO pins like the GertVGA666 use 6bit per channel colour, so you go from 24bit colour (16M colours) to 18bit colour (262K colours). 
https://www.pi-supply.com/product/gert-vga-666-hardware-vga-raspberry-pi/

Given the limited colour pallets of most games, you probably won't notice.

2) Again, if you're using GPIO, you lose your pins for controller input.  Not a huge deal if you're using USB inputs.

3) Digital solutions that use HDMI to VGA converters are susceptible to the converter itself.  If you can find one that doesn't scale the image and just obeys the resolution sent from the Pi, then that's OK.  Nothing guaranteed though, especially with the proliferation of cheap hardware that all gets rebranded over and over.

4) And I think this is the biggest downside: you're locked to 50.00Hz or 60.00Hz vertical refresh output modes only.  That's fine for most console emulation, but there quite a lot of handheld and arcade hardware that doesn't run exactly 60Hz.  That means you're changing game timings slightly to force the sync for many things.  It does mean you don't have to go changing your monitor settings every time, but you don't get the exact modeline control like you would out of GroovyMAME and Switchres, for example.

That last point really depends on your own personal pedantry.  For casual fun, it's not an issue, and 90% of people won't notice.  If you care about exact modelines, it's not going to satisfy you.

With that said, I have a "NeoGeo" cabinet with an enormous, bulky PC inside it.  Switching that out to an RPi would be mighty nice, even with the inaccurate display modes.