Chameleon-AVR Nurve Networks, Chameleon-AVR Datasheet - Page 49

• 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”
11.2.4 Color Encoding
Color information is superimposed on top of the luma (brightness) signal and is a sine wave with the colors identified by a
specific phase difference between it and the color-burst reference phase at the beginning of each scanline. This can be
seen in Figure 11.6(c), which shows a horizontal scan line of color bars.
Figure 11.6 (c) - Composite Video Waveform of the Color Bars.
The amplitude of the modulation is proportional to the amount of color (or saturation), and the phase information denotes
the tint (or hue) of the color. The horizontal blanking portion contains the horizontal synchronizing pulse (sync pulse) as
well as the color reference (color burst) located just after the rising edge of the sync pulse (called the "back porch"). It is
important to note here that the horizontal blanking portion of the signal is positioned in time such that it is not visible on the
display screen.
11.2.5 Putting it All Together
Generating a NTSC (or PAL) signal means controlling the signal into the TV such that all the timing specifications are met.
There are a number of aspects that must be taken into consideration to achieve this successfully. However, one important
detail is that the video signal does not have to be perfect, that is, the timings can be slightly off per line, per frame, per
color burst, etc. nevertheless, the amount of “slack” must be consistent. In general here are the steps to generating an
NTSC signal.
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