RGB on a raspeberry pi and other pi questions

(If this is not the correct subforum point me to the correct one )

So, I want to build a raspberry pie as a present for a friend in order to play classic games. I also want to add an RGB scart plug so that he can play those games on his CRT on 15 Khz glory.
So far I'm between these adapters

• arcadeforge's pi2scart
  
• a generic scart to gpio adapter

Are there any significant differences between choosing one of these two adapters?

If I choose the arcadeforge adapter, there is a pre-configured file with emulators settings etc. Is there a way to add a gameboy,gameboy color,gameboy advance and game gear emulator? It seems that they aren't supported on this file.
Can I use a usb powered hard drive to load roms instead of using an sd card? My friend has an hdd full of roms that would like to use on the pi.

 

I believe you just create a "retropie-mount" folder on the HDD and retropie should configure it automatically. You'd probably have to then move the roms into the right folder.

 

pi2scart seems to be better : sync stripper, jack output.
The «generic» version is too pricey.

 

I did some research, and indeed the arcadeforge one seems to be a better choice. I'll order this one then.
One more question. I have an old snes to usb adapter that is no more supported by modern windows machines.
Can I use it on the pi as a plug'n'play device, or it needs extra drivers?

 

You should also be able to use Gert's VGA666, I believe. I'm not sure how you get it to run at 15 kHz, though... haven't had the time to look.

Looks like you can do it with code:

http://retrorgb.com/rpi240p.html

It'll be a lot cheaper that way, no doubt.

 

I have considered using this adapter,but it's not suitable. We're going to use the pi on a scart tv. This adapter will probably need some extra hardware to convert the vga signal to scart.

 

These designs are all based on Gert's VGA666.
You can get 15khz by changing settings on boot time, or using vcgencmd software.

 

Is there a simple way to get scart output from Gert's VGA? I did some research and all I found is an external scart adapter.

 

You can build a simple VGA to SCART cable.

 

This is all you need right here. I plan to buy one soon myself!
http://www.retrotink.com/

He even includes a premade image on his website (without roms) that's already configured for 240p.

 

So I got hold of a raspberry pi 3 and started testing things out. I'm new to raspberry and have to learn some stuff.
First of all, I noticed that using the retropie image that is available in the arcadeforge scart adapter, I get noting on the screen when I use hdmi.
I get the same results if I use the regular retropie image and the extra settings for the adapter to work in the config file.
What can I do in order to be able to run the pi both in hdmi and scart? Keep separate sd cards one with the extra settings and one unchanged?

Also, browsing youtube I found this diy gpio this guy though has some extra components for a pvm. Can I use this one? I'll need some extra help though from people with the appropriate tools, as I don't have any for homebrew pcb sketching

 

Pi2scart Is great

 

Kinda. Since all the magic sauce is in the config.txt, you can keep two cards, or just have a copy of both variants of this file on one sd and replace it accordingly. Of course that'd mean you need to know what video mode you want to boot with next, or to find a way to switch out the file w/o video output from the pi (worst case, stick the card in a pc and do it from there).

 

After a lot of trial and error, I managed to get a retropie configuration the way I want it, but still have some issues.
The first one is how do I define diferent keys for individual games. for example I want to define different keys for a metal slug a shmup or a two button run'n'gun arcade game, as it's more convenient for my friend's x-arcade stick to have those keys on the lower buttons.
The second is how do I have access on the TAB button settings on mame.