simple NTSC black and white driver
dr hydra
Posts: 212
I am working a simple bit bang (no special hardware) NTSC black and white video driver (like 128x200) interlaced. I know the propeller can do a lot more, but this is just a learning exercise. I got most of it worked out in my head, but I do not fully understand Pre/post equalizing pulses and the vertical synch pulse. I am going to use two pins
one for video and one for sync. I will have three voltages (1 white .3 black and 0 for sync). Also, I am planning on using the waitcnt command and 5090 clocks for each scanline. So if I understand NTSC video correctly
lines 1-22 0 volts for 10.9us(hsync) and .3 volts (black) for 52.6us(top of the screen)
lines 23-222 0 volts for 10.9us(hsync) and 1 volt to .3 volts for 52.6(active video)
lines 223-243 0 volts for 10.9(hsync) and .3 volts(black) for 52.6us(bottom of the screen)
lines 244-250 Pre equalizing 0 volts for 10.9(hsync) and .3 volts(black) for 52.6us
lines 250-256 vertical synch I am not sure (please help)
lines 256-262 Post equalizing 0 volts for 10.9(hysnc) and .3 volts(black) for 52.6us
Is that close to what is needed if so, both pre/post equalizing lines are just simple black video lines and what does the vertical synch line look like?
lines 1-22 0 volts for 10.9us(hsync) and .3 volts (black) for 52.6us(top of the screen)
lines 23-222 0 volts for 10.9us(hsync) and 1 volt to .3 volts for 52.6(active video)
lines 223-243 0 volts for 10.9(hsync) and .3 volts(black) for 52.6us(bottom of the screen)
lines 244-250 Pre equalizing 0 volts for 10.9(hsync) and .3 volts(black) for 52.6us
lines 250-256 vertical synch I am not sure (please help)
lines 256-262 Post equalizing 0 volts for 10.9(hysnc) and .3 volts(black) for 52.6us
Is that close to what is needed if so, both pre/post equalizing lines are just simple black video lines and what does the vertical synch line look like?