The VGA Adapter module is very flexible and can scale to meet your projects needs. The default package uses 1 bit/channel (3 bits total) to represent color information. You can scale this value to 3 bits/channel (9 bits total). Increasing this value provides a broader range of colors but decreases the available memory on the DE2 Educational Board. In order to change the channel depth, modify the COLOR_CHANNEL_DEPTH constant in VgaAdapter.v to the desired channel depth.
Alternatively, you can change the mode of operation to Black and White and reduce the size of the color bus to 1 bit total. This can help tremendously with projects that require a large amount of internal memory. To switch to this mode of operation, change the value of the COLOR_MODE constant in VgaAdapter.v to 0.
The following table provides a comparison between the various modes of operation and color depths.
Mode | Bits/Channel | Total Bits | Color Range | Memory Usage (bits) | Memory Usage (%) |
Black & White | - | 1 | 2 | 32,768 | 7% |
Color | 1 | 3 | 8 | 98,304 | 20% |
Color | 2 | 6 | 64 | 196,608 | 41% |
Color | 3 | 9 | 512 | 294,912 | 60% |
Color | 4 | 12 | 4,096 | 393,216 | 81% |