MC44002 MC44007
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MOTOROLA ANALOG IC DEVICE DATA
Introduction
The following information describes the basic operation of
the MC44002/7 IC together with the MC44140 chroma delay
line. The MC44002/7 is a highly advanced circuit which
performs all the video processing, timebase and display
functions needed for a modern color TV. The device employs
analog circuitry but with the difference that all its advanced
features are under processor control, enabling external
filtering and potentiometer adjustments to be removed
completely. Sophisticated feedback control techniques have
been used throughout the design to ensure stable operating
conditions and the absence of drift with age.
The IC described herein is one of a new generation of TV
circuits, which make use of a serial data bus to carry out
control functions. Its revolutionary design concept permits a
level of integration and degree of flexibility never achieved
before. The MC44002/7 consists of a single bipolar VLSI chip
which uses a high density, high frequency, low voltage
process called MOSAIC 1.5. Contained within this single 40
pin package is all the circuitry needed for the video signal
processing, horizontal and vertical timebases and CRT
display control for today’s color TV. Furthermore, all the user
controls and manufacturer’s set-up adjustments are under
the control of the processor I2C bus, eliminating the need for
potentiometer controls. The MC44002/7 offers an enormous
variety of different options configurable in software, to cater
to virtually any video standard or circumstance commonly
met. The decoder section offers full multistandard capability,
able to handle PAL, SECAM (MC44002 only) and NTSC
standards with 4 matrix modes available. Practically all the
filtering is carried out onboard the IC by means of sampled
data filters, and requires no external components or
adjustment.
Digital Interface
One of the most important features of MC44002/7 is the
use of processor control to replace external potentiometer
and filter adjustments. Great flexibility is possible using
processor control, as each user can configure the software to
suit their individual application. The circuit operates on a
bidirectional serial data bus, based on the well known I2C
bus. This system is rapidly becoming a world standard for the
control of consumer equipment.
I2C Bus
It is not within the scope of this data sheet to describe in
detail the functioning of the I2C bus. Basically, the I2C bus is
a two-wire bidirectional system consisting of a clock and a
serial data stream. The write cycle consists of 3 bytes of data
and 3 acknowledge bits. The first byte is the Chip Address,
the second the Sub-address to identify the location in the
memory, and the third byte is the data. When the address’
Read/Write bit is high, the second and third bytes are used to
transmit status flags back to the MCU.
Figure 6 shows a block diagram of the MC44002/7 Bus
Interface/Decoder. To begin with, the start bit is recognized
by means of the data going low during CLK high. This causes
the Counter and all the latches to be reset. For a write
operation, the Write address ($88) is read into the Shift
Register. If the correct address is identified, the Chip Address
Latch is set and at CLK 9 an acknowledge is sent.
The second byte is now read into the Shift Register and is
used to select the Sub-address. At CLK 18 a Sub-address
Enable is sent to the memory to allow the Data in the register
to be changed. Also, at CLK 18 another acknowledge is sent.
The third byte is now read into the Shift Register and the
Data bussed into the memory. The Data in the Sub-address
location already selected is then altered. A third acknowledge
is sent at CLK 27 to complete the cycle.
A Read address ($89) indicates that the MCU wants to
read the MC44002/7 status flags. In this instance, the
Read/Write Latch is set, causing the Memory Enable and
Subaddress Enable to be inhibited, and the flags to be written
onto the data line. Two of the status flags are permanently
wired one-high and one-low (O.K. and Fault), to provide a
check on the communication medium between the
MC44002/7 and the MCU.
At start-up the Counter is automatically reset and the Data
for each Sub-address is read in from the MCU. Only after the
entire memory contents have been transmitted, is Data 00
sent to register 00 to start the Horizontal Drive.
The MC44002/7 needs the full 27 clock cycles, or a stop
condition, to properly release the I2C bus.
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Figure 6. I2C Bus Interface and Decoder
8-Bit Shift Register
Read/Write
Latch
Chip-Address
Latch
Sub-Address
Latches
Memory &
Sub-Address
Decoding
Acknowledge
Data
Clock
Clock Counter
Reset
Start-Bit
Recognition
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8
8-Bit
8-Bit