First of all if "Rainbow mod" is not another name for "Mode Select Hack" then sorry for posting in the wrong section.

I really like your SNES mod : http://www.bradsprojects.com/electronic ... tHack.html

Do you think it could be improved by adding region selection with control of pin 4 of the F413 chip (to play import games) and still with one 16f628a ?

Can we perform PWM (Pulse Width Modulation) on LEDs with 16f628a ?

If yes, it could be cool to see selected mode as something like this (or another colors table, the following one was the first popping up in my mind) :
Red 50 Hz / original region
Green 60 Hz / original region
Red/Blue* 50 Hz / region free
Green/Blue* 60 Hz / region free

*A combination of 2 colors glowing successively and progressively.

Sorry - I have called it different things, but you are correct - they are the same project

You could add extra modes all from the same microcontroller.

Also, you don't even need to use PWM - you can just turn on multiple LED colors at the same time.

if you turn RED and GREEN on you get ORANGE
if you turn RED and BLUE on you get MAGENTA
if you turn Green and Blue on you get CYAN
if you turn all three on you get WHITE

Yes, I forgot about this way to combine colors, thanks.
I was too focused on PWM because it can create a nice and subtle effect.

But, can we create (good working) PWM from this microcontroller or do you know an easiest way to do it ?

I would like to adapt it to my SEGA MegaDrive and to my SEGA Nomad which I have recently changed the screen. The brightness wheel now useless will be used to select region and frequency.

[Edit] Seems possible

Yes PWM is achievable with a 16f648a / 16f628a although I have never actually done it.

You can do it by one of two methods - either use the inbuilt PWM feature of the chip, or you could write it for yourself in code and use a standard digital output port pin.

I think bitfogav experimented with PWM if I remember correctly?

I have a sega game gear but not the NOMAD

i like old school games!

Its easier using code to do the PWM as you are limited to only 1 port pin using the CCP module of the microchip, and as you want to use a RGB Led then your need 3 pins atleast.

I would suggest looking at Stacys tutorial about PWM first, this may help you?

http://www.bradsprojects.com/forum/viewtopic.php?f=20&t=170

And also I find this website a great help with PWM too.

http://picprojects.org.uk/projects/rgb2/index.htm

It would be alot easier if you used a higher programming language like Swordfish aswell but that would mean using a higher performance microchip 18F

Thanks to both of you for the hints, I'll read and study carefully your links bitfogav.

brad, I'm fond of retro gaming, I like 2D, pixels and immediate fun. I think I'm starting to have a nice collection with nearly all console systems.
Recently I had good luck with an eBay auction, two Nomad (one with a broken screen and one in perfect shape) and no-one was bidding, I guess because the seller wasn't sending outside US. Then I asked him if he could ship to my bro' in law near L.A., he said yes and I got them for $60.

That's a Great price for the nomads. I used to collect retro video games for years. Infac I had a retro video game site.
http://Www.retrobrad.org

I don't update it anymore, but it still online.

I guess that's why most of my projects are based around retro games