SM320DM642-EP Datasheet, PDF (148/170 Pages) Texas Instruments – Video/Imaging Fixed Point Digital Signal Processor

SM320DM642-EP
Video/Imaging Fixed Point Digital Signal Processor
SGUS058B – JUNE 2007 – REVISED JANUARY 2008
www.ti.com
5.15 VCXO Interpolated Control (VIC)
The VIC can be used in conjunction with the Video Ports (VPs) to maintain synchronization of a video
stream. The VIC can also be used to control a VCXO to adjust the pixel clock rate to a video port.
5.15.1 VIC Device-Specific Information
The VCXO interpolated control (VIC) port provides digital-to-analog conversation with resolution from
9-bits to up to 16-bits. The output of the VIC is a single bit interpolated D/A output (VDAC pin).
Typical D/A converters provide a discrete output level for every value of the digital word that is being
converted. This is a problem for digital words that are long. This is avoided in a Sigma Delta type D/A
converter by choosing a few widely spaced output levels and interpolating values between them. The
interpolating mechanism causes the output to oscillate rapidly between the levels in such a manner that
the average output represents the value of input code.
In the VIC, two output levels are chosen (0 and 1), and Sigma Delta interpolation scheme is implemented
to interpolate between these levels with a rapidly changing signal. The frequency of interpolation is
dependent on the resolution needed.
When the video port is used in transport stream interface (TSI) mode, the VIC port is used to control the
system clock, VCXO, for MPEG transport stream.
The VIC supports the following features:
• Single interpolation for D/A conversion
• Programmable precision from 9-to-16 bits
• Interface for register accesses
For more detailed information on the DM642 VCXO interpolated control (VIC) peripheral, see the
TMS320C64x™ DSP Video Port/VCXO Interpolated Control (VIC) Port Reference Guide (literature
number SPRU629).
5.15.2 VIC Peripheral Register Description(s)
Table 5-68. VCXO Interpolated Control (VIC) Port Registers
HEX ADDRESS RANGE
01C4 C000
01C4 C004
01C4 C008
01C4 C00C – 01C4 FFFF
ACRONYM
VICCTL
VICIN
VPDIV
–
REGISTER NAME
VIC control register
VIC input register
VIC clock divider register
Reserved
148 DM642 Peripheral Information and Electrical Specifications
Submit Documentation Feedback