In SX Microcontrollers, SX/B Compiler and SX-Key Tool, bean wrote:

The driver is setup so that the first line (LINE 0) has a seperate tile set. This is so that you can display a value using digits zero thru nine without using up 10 of your 16 tiles. These are the 16 data lines starting at the label "TilePatterns:". NOTE: The last tile in each set should be blank (if you need a blank tile).

The pong and sketch examples setup the game tiles (the next 16 data lines) as every possible combination of quarter tile "cells" filled and unfilled. Then I have routines in the game code to plot and unplot these quarter cells. So even though you have 32 cells (not tiles) by 22 cells (not tiles) that is about the best resolution you can get. This is just something done in the game code and the MMVGD driver knows nothing about it.

You are right that the screen resolution is 128 x 88, but if you needed to store an image with unique pixels it would take 128*88 / 8 = 1408 bytes. The SX28 doesn't have near enough RAM to hold it.

Because of the limited RAM in the SX28 that seemed like a good comprimise. Because you need to leave some RAM for the user game too.

With a SX48 and an external SRAM chip you could make a circuit with 256x192 resolution without a lot of trouble. That's about as good as you can get with NTSC video. Problem is that the screen would take about 6K of memory, so you would need an external EEPROM or something non-volitile to hold the screen image.

Bean.

---------- End of Message ----------


You can view the post on-line at:
http://forums.parallax.com/forums/default.aspx?f=7&p=1&m=140523#m140525

Need assistance? Send an email to the Forum Administrator at forumadmin@parallax.com

The Parallax Forums are powered by dotNetBB Forums, copyright 2002-2006 (http://www.dotNetBB.com)