Chameleon-PIC Nurve Networks, Chameleon-PIC Datasheet - Page 40

• Manufacturer Part Number: Chameleon-PIC
• Description: MCU, MPU & DSP Development Tools PIC24 & PROPELLER DEV SYSTEM (SBC)
• Manufacturer: Nurve Networks

Specifications of Chameleon-PIC

• Processor To Be Evaluated: PIC24
• Data Bus Width: 16 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

10.2 VGA Hardware Interface
The VGA hardware for the Chameleon is very minimal since the Propeller chip is doing all the signal generation with direct
control of the VGA signal via its built in VSU (video streaming unit). Of course, someone still has to write a driver for the
VGA to work on the Propeller, but that’s been done 100x. Referring to Figure 10.1, you see that there are 8 signals
connected to the VGA port, Table 10.1 shows the relationship between I/O port bits and signals.
There are 2-bits for each channel; Red, Green, and Blue as well as a single bit for HSYNC and VSYNC which are TTL
level. These outputs are connected directly to the HD15 connector via a series of 2-bit D/A converters that sum each 2-bit
channel pair (R1, R0), (G1, G0), and (B1, B0) and directly interface the sync bits. The VGA spec dictates that for each
channel 0% intensity is 0.0V and 100% intensity is 1.0V (some references use 0.7V). Also, each channel input to the VGA
monitor itself per input has a nominal impedance of 75 Ohms (similar to the NTSC input impedance).
Prop Port Bit
P23
P22
P21
P20
P19
P18
P17
P16
Figure 10.1 – The Chameleon PIC VGA interface and support hardware.
Chameleon Signal
VGA_RED_B1
VGA_RED_B0
VGA_GREEN_B1
VGA_GREEN_B0
VGA_BLUE_B1
VGA_BLUE_B0
VGA_HSYNC
VGA_VSYNC
Table 10.1 – The Video Hardware.
e Port Mapping Bits.
© 2009 NURVE NETWORKS LLC “Exploring the Chameleon PIC 16-Bit”
Description
Bit 0 of RED channel.
Bit 1 of RED channel.
Bit 0 of GREEN channel.
Bit 1 of GREEN channel.
Bit 0 of BLUE channel.
Bit 1 of BLUE channel.
VGA HSYNC TTL level.
VGA VSYNC TTL level.
40