|The GBS8200 is an upscaler that is
designed to convert 15KHz RGB video to VGA. It works, but the picture
isn't as good as it could be when used with old video games and home
computers, because it tries to deinterlace already non-interlaced video
and it applies unnecessary smoothing.
This project replaces the onboard controller with an ATMega861, plugged into the I2C connector on the GBS8200. Two tables are stored in the ATMega's Flash ROM, with settings for 240p (NTSC) and 288p (PAL). The switch selects between them, and the LED shows which resolution is selected. The 6 pin ISP connector is for programming the AVR.
My code is based on the Ardiuno version by 'mybook4' on Github. I used the ATMega861 because I had a few spare, but it could easily be ported to any AVR (or other MCU) that has at least 8k of ROM and 2~4 free I/O pins.
|zip archive with source code, hex file and circuit diagram.|
|With the onboard controller disabled the buttons on the
GBS8200 are redundant, so I put the board into a nice case with just
the RGB inputs and resolution switch on the front. No more fiddling around in
on-screen menus trying to get the best picture!