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6.5.
LTC/VITC GENERATOR MODULE CIRCUIT DESCRIPTION
TECHNICAL DESCRIPTION
The 615 module can be reset to factory defaults by the following
procedure.
1.
Unplug the 615 or power down the 4025.
2.
Flip the DIP switches to the exact opposite of the current switch
settings.
3.
Push the 615 back in/or power up the 4025.
4.
Allow the 4025 to go through the normal power up displays.
5.
Check that 615 has reset the keykode head offsets to NONE.
6.
With power on reset the 615 DIP switches to original settings.
The 615 LTC/VITC generator is a microcontroller based module
functionally divided into the following hardware subsystems:
1. Microcontroller & I/O
2. Sync Separator/Video processing
3. Colour Frame Detector
4. Telecine Interface
5. VITC Generator Logic
6. VITC Keyer
The microcontroller, LTC generator, and video processing circuits are
contained on the main circuit card (6150). The VITC generator circuitry is
contained on a separate sub-module (6231) which plugs into the main
module. Input buffers and all input/output connectors are contained on a
separate I/O module, (7006) to which the 615 module plugs in. Sections
6.4.1 to 6.4.5 inclusive describe the operation of circuitry on the 6150 main
board.
Section 6.7.1 to 6.7.3 describes the operation of the VITC
generator / Character inserter circuitry contained on the 6231 sub-module.
The relevant schematic drawings are shown in brackets for each section of
the circuit.
6.5.1. Microcontroller & Programmable Logic (6150-32 & 6150-33)
At the heart of the 615 LTC/VITC generator module is an 8032
microcontroller, (MCU) U9. Its three 8 bit bi-directional ports and 8 bit bus
provide peripheral interfacing to the rest of the circuits. Program memory is
contained on EPROM U12. The EPROM is divided into two halves, with
the upper addressing for the PAL video standard, and the lower addressing
for the NTSC video standard. The correct half of the EPROM is selected
by pin 33 of the LCA. Scratch pad and data RAM are provided internally by
the MCU. A programmable logic cell array, (LCA) U10 contains address
decoding and glue logic for various peripherals on the board.
An onboard oscillator, also part of the LCA, is crystal controlled. Its' 9.216
MHz frequency (test point T7) is used in conjunction with phase locked
loop U15 to generate a microprocessor clock frequency of 11.50849 MHz
Model 4025 Film Footage Encoder Manual
Page 6-15
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