Chameleon-AVR Nurve Networks, Chameleon-AVR Datasheet - Page 183

• Manufacturer Part Number: Chameleon-AVR
• Description: MCU, MPU & DSP Development Tools AVR8 & PROPELLER DEV SYSTEM (SBC)
• Manufacturer: Nurve Networks

Specifications of Chameleon-AVR

• Processor To Be Evaluated: AVR 328P
• Data Bus Width: 8 bit
• Interface Type: USB, VGA, PS/2, I2C, ISP, SPI
• Operating Supply Voltage: 3.3 V, 5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

© 2009 NURVE NETWORKS LLC “Exploring the Chameleon AVR 8-Bit”
I have highlighted the register access code fragments at the top of each section. So the idea is the AVR/PIC sends the
GFX command message via SPI, the SPI message dispatcher catches these messages and passes all of them to the
function, then this function, cases on each possible register access message and processes it – viola! Of course, the
above code is a partial listing, the complete function is really long and you can look it yourself in the Propeller source file.
GPU Functions Overview
These functions deserve a bit of explanation. I am using the word “GPU” pretty freely here and its not meant to infer there
is a hidden GPU somewhere, but rather than indicate that the hardware or driver is capable of doing large operations via a
single command. Two things that we do a lot of in computer graphics is copying data and moving data. Copy, move, copy,
move, copy, move. 90% of operations are copy, move! So, one thing you want you GPU/graphics engine, software,
whatever to do is copy and move – fast!
Thus, one of the simple additions to the tile driver is the ability to copy and fill memory. So, I added some sub-functions
that I call “GPU functions” these are macro level functions that can fill and copy memory 8/16 bits at a time. If you take a
look at the listing above at the very top you will see the processing of GPU sub-functions. First, we use the SPI command
itself to identify a GPU function, the register messages are GPU_GFX_SUBFUNC_STATUS_R and
GPU_GFX_SUBFUNC_STATUS_W. The “R” or read message currently does nothing, but the “W” or write message
executes the GPU command which there are currently 4 of as shown in the header code below:
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