The VGA monitor is basically analog monitor with individual Red, Green, Blue with H-Sync & V-Sync inputs. You can find the connection details on net. If I find some, I'll put here.
In which way, you mean controlling the VGA monitor? By varying the voltage levels, analog levels, not digital values, we can virtually show infinite colors on VGA screen, which is one of the speciality of VGA CRT displays. But the horizontal & vertical sync pulses should be taken care of properly, by your embedded system.
The VGA cards, use high speed Digital to Analog Converters to convert the input digital value to equivalant analog voltage on perticular pin. A 24bit colour display shows, the first byte is loaded to Red DAC, second byte to Green DAC & finally the third byte to Blue DAC. Of course, it might not be so simple as I keyed in here. There might be some correction factors applied to individual colour values. Except for the H-Sync & V-Sync pulses, R, G & B are continuous in the range of 0-5V. The sync pulses are descrete between 0-5V.
Hence, to show a scene on VGA screen, use three DAC's, one each for Red, Green & Blue. They should be of high speed, but resolution can be less, for example, an 8 bit total will show only 256 colours & it's good amount for a small embedded system. All that you need to do, is to split the colour value across three DAC's.
The best bet I have is, grab some good old VGA card for ISA bus, interface it to your microcontroller and load the colour values into the card's VGA array & lo! Your VGA info is on screen. You don't need to generate any H-Sync or V-Sync. But you need to program the card, of course you can get it from programmer's manual for that card.
Hope this helps, need more, can contact
just_srinu@yahoo.com
Srinu