Vga

[AtomSoft]

Hey everyone, im embarking on yet another VGA trial... but this time using a ARM.. also i i read that VGA signal can be 0.7v-1v so i devised a voltage divider using:

VOUT = R1/(R1+R2)

So i got R1 as 100 and R2 as 240.. it gives me a output of .97v

You think using a Voltage Divider for this purpose is ok?

 

[ronsimpson]

First thought. R1//R2 gives 70 ohms that is close to the 75 ohms impediance of the coax.

Next thought. I don't know if your VGA monitor is AC coupled or DC coupled. But at frequencies from 10hz to 50mhz the VGA input will look like 75 ohms. If it is AC coupled it will look open at DC. Any way....there is a 75 ohm resistor in the monitor that will effect your resistor divider.

The H and V syc inputs may be 10k ohms and need TTL levels.
The analog RGB inputs are 75 ohm. Some VGA monitors will strip H & V sync from green if H & V sync is not there.
The RGB inputs must be at black during blanking times.
If you send sync on green then sync is below the black level.