VGA/Video Adapter Circuit Schematic

VGA/Video Adapter Schematic

VGA/Video Adapter Circuit

VGA-terminal:
Quantity of symbols: 20 lines by 20 characters.
The resolution of a character matrix: 8x12 points
Supported code page: WIN 1251
Formed signal: VGA
The resolution: 640x480
Frequency of vertical synchronization: 60Hz
Speed of exchange UART 19200 bps

Video terminal:
Quantity of symbols: 20 lines by 38 characters.
The resolution of an individual character matrix: 8x12 points
Supported code page: WIN 1251
Formed signal: Composite Video (PAL/SECAM)
Resolution: 625 lines (interlaced)
Frequency of vertical synchronization: 50Hz
Speed of exchange UART 19200 bps

Type of the used microcontroller: Mega8, Mega16, Mega32, Mega8535, etc.

Clock frequency of the microcontroller standard - 16Mhz.

Notes:

1. To avoid distortion of the image, when receiving data through the UART, for VGA, it is recommended to make the data exchange with the terminal in approximately 300-600 us after a signal of vertical synchronization (VSYNC).

2. The available internal RAM of the Mega8535 (only 512 bytes) is not enough for the formation of a Video signal with a resolution of 38x20 symbols.