This is a design circuit for vga adapter. This circuit have some characteristic. This is the figure of the circuit;
Initial calculations showed that the the AVR 8-bit microcontroller from ATMEL, with its 16Mhz clock speed providing approximately 16 MIPS was a good candidate for further research. Also note that newer AVRs such as the Mega48, Mega88 and Mega168 will officially support clock rates upto 20 Mhz. Therefore I concluded that with a clock of 16 Mhz I could achieve something in the order of 8 Mhz speed of data being transferred out of a port. I also chose the AVR as I had already built up quite a body of experience with it and so I began work of the project. 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). 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.
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