Re: [uCsimm] Dragonball on TV

From: Micah Dowty (
Date: Sat Jan 06 2001 - 13:41:44 EST

I've done a bit of TV interfacing with a PIC. Color is tricky, but black
and white should be relatively easy. I don't know what kind of resolution
this would give you, but maybe you could try putting the LCD controller in
4-bit mode, then connecting a resistor network or cheap DAC to the
output. A resistor network might be better, so you could tweak the level
of each possible output.
In composite NTSC video (I don't know PAL but I would assume it's
similar) black is at some voltage above zero (0.25V IIRC) shades between
black and white range between that and 1V, and a sync pulse drops to 0V.
If you could allocate a sufficient amount of video memory to handle the
picture itself and the sync pulses, you could get 15-grayscale TV output
with only a few resistors.

On Sat, 6 Jan 2001, Raj Kumar wrote:

> Hi everybody,
> I am working on a project that requires me to interface a MC68EZ328 to a standard colour TV. I am planning to use uClinux.
> Has anyone out there worked with / interfaced a low cost TV/Video controller to the Dragonball ? The primary objective is to display text (English) onscreen. Bit mapped graphics would be great ! Colour display would be even better !!
> I need to keep costs low. I am looking for a simple / single chip solution (without extra Video memory etc.)
> Has anybody tried/thought of tweaking the onboard LCD controller to generate TV timings ? (HSync/Line Pulse of 15 KHz and VSync/Frame Pulse of 50 Hz) ?
> Any feedback will help.
> Raj Kumar
> Bangalore, India

>From the command line of Micah Dowty.

2 + 2 = 5, for very large values of 2

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