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DE2-70 User Manual
67
• Optionally connect a VGA display to the VGA D-SUB connector. When connected, the
VGA display should show a pattern of colors
• Optionally connect a powered speaker to the stereo audio-out jack
• Place toggle switch SW17 in the UP position to hear a 1 kHz humming sound from the
audio-out port. Alternatively, if switch SW17 is DOWN, the microphone-in port can be
connected to a microphone to hear voice sounds, or the line-in port can be used to play audio
from an appropriate sound source
The Verilog source code for this demonstration is provided in the DE2_70_Default folder, which
also includes the necessary files for the corresponding Quartus II project. The top-level Verilog file,
called DE2_70_Default.v, can be used as a template for other projects, because it defines ports that
correspond to all of the user-accessible pins on the Cyclone II FPGA.
6.2 TV Box Demonstration
This demonstration plays video and audio input from a DVD player using the VGA output, audio
CODEC, and one TV decoder (U11) on the DE2-70 board. Figure 6.1 shows the block diagram of
the design. There are two major blocks in the circuit, called I2C_AV_Config and TV_to_VGA. The
TV_to_VGA block consists of the ITU-R 656 Decoder, SDRAM Frame Buffer, YUV422 to YUV444,
YCrCb to RGB, and VGA Controller. The figure also shows the TV Decoder (ADV7180) and the
VGA DAC (ADV7123) chips used.
As soon as the bit stream is downloaded into the FPGA, the register values of the TV Decoder chip
are used to configure the TV decoder via the I2C_AV_Config block, which uses the I2C protocol to
communicate with the TV Decoder chip. Following the power-on sequence, the TV Decoder chip
will be unstable for a time period; the Lock Detector is responsible for detecting this instability.
The ITU-R 656 Decoder block extracts YCrCb 4:2:2 (YUV 4:2:2) video signals from the ITU-R 656
data stream sent from the TV Decoder. It also generates a data valid control signal indicating the
valid period of data output. Because the video signal from the TV Decoder is interlaced, we need to
perform de-interlacing on the data source. We used the SDRAM Frame Buffer and a field selection
multiplexer(MUX) which is controled by the VGA controller to perform the de-interlacing operation.
Internally, the VGA Controller generates data request and odd/even selected signals to the SDRAM
Frame Buffer and filed selection multiplexer(MUX). The YUV422 to YUV444 block converts the
selected YCrCb 4:2:2 (YUV 4:2:2) video data to the YCrCb 4:4:4 (YUV 4:4:4) video data format.
Finally, the YCrCb_to_RGB block converts the YCrCb data into RGB output. The VGA Controller
block generates standard VGA sync signals VGA_HS and VGA_VS to enable the display on a VGA