Computer

Composite video with Atmega328p

Last Updated or created 2022-10-21

I started to get some composite video generated with a arduino for my 6502 project.

UPDATE: 20221021

It is based on Grant Searle’s design, and yesterday I had some signals on my scope which looked like a screen with a character. But my monitor would not recognize a usable signal.

Today I tried a second version and another set of chips and crystals.

It looks like a signal, but I can’t see a clock pulse from the crystal?! So .. how?

Maybe I used a bad power supply. And killed something?

UPDATE: 20221021

After switching to another power supply, and checking the atmega328p fuses again (also wrong) .. at least SOME success!

Still a little sync problem, but i’ve got a blinking cursor!
Some minipro info
#Erase
minipro -p ATMEGA328P@DIP28 -E

#Flash hex code
minipro -p ATMEGA328P@DIP28 -w SBCVideo.hex

#Flash fuses
minipro -p ATMEGA328P@DIP28 -e -c config -w fuses

#Used fuses file
fuses_lo = 0xf7
fuses_hi = 0xd9
fuses_ext = 0xff
lock_byte = 0xff

#Dump all from atmega328p
minipro -p ATMEGA328P@DIP28 -r dump -f ihex

Some info about the fuses:
https://www.allaboutcircuits.com/projects/atmega328p-fuse-bits-and-an-external-crystal-oscillator