µ[micro]electronics info

A weblog focused on interesting circuits, ideas, schematics and other information about microelectronics and microcontrollers.




Because I have not tested all electronic circuits mentioned on this pages, I cannot attest to their accuracy; therefore, I do not provide a warranty of any kind and cannot be held responsible in any manner.

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VGA display with PIC18F controller

I've finally found a circuit I've been looking for for quite a long time - the VGA-compatible display based on plain microcontroller.

Author says: "The primary motivation in moving video RAM out of the PIC microcontroller is to increase the potential screen resolution. Since each pixel comes from SRAM, computation in the microcontroller simply becomes a memory address increment. Block(?) diagram The PIC INCF instruction executes in only one instruction cycle. At 10MIPS, this gives a theoretical maximum of 251 instructions or 251 horizontal pixels.

This approach yields one byte per pixel. I will initially just use one bit per color for testing - which is 8 colors (23). Since a full byte is available, I hope to expand this to 256 colors. The odd thing is that 8 is an even number and doesn't divide by 3 "nicely". What I am hoping will work out is to divide the bits up into XYRRGGBB. "XY" will be prepended to each color pixel - giving XYRR for red, XYGG for green, and XYBB for blue.

The SRAM, being 32K in size, has an address bus of 15 bits. Using 8 bits for horizontal resolution leaves 7 bits, or 128 lines, for vertical resolution."

Link: PIC18F VGA Video

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