[Coco] RGB2VGA on DE0-Nano (improvements)

[Mark McDougall]

On 29/08/2014 10:28 PM, Retro Canada wrote:

> i can't buffer an analog signal. but the problem is the clock. the buffer
> i use has 4ns slew rate which is nothing.

Your problem is that you're not locking to the HSYNC on every line. Jitter 
in the HSYNC will cause jitter in your sampling and hence your waving 
output. You also need an *accurate* pixel clock that can be tuned to match 
the Coco3's clock, else you'll get cumulative errors across each line in 
your sampling.

Read the TVP7002 datasheet (TI) to get an idea of what you need to get a 
decent sampled analogue signal.

You've likely reached the limit of your hardware.

Regards,

-- 
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"