MC44BC374 MOTOROLA [Motorola, Inc], MC44BC374 Datasheet - Page 20

• Manufacturer Part Number: MC44BC374
• Description: PLL Tuned PAL/NTSC UHF and VHF Audio/ Video High Integration Modulator IC
• Manufacturer: MOTOROLA [Motorola, Inc]

High Speed I2C Compatible Bus
14.4 High Speed I
14.5 I
The bus receiver operates the I
In write mode, each ninth data bit (bits 9, 18, 27, 36, and 45) is an acknowledge bit (ACK) during which
the MCU sends a logic 1 and the Modulator circuit answers on the data line by pulling it low. Besides the
chip address, the circuit needs two (2) or four (4) data bytes for operation. The following sequences of data
bytes are the permitted incoming information:
After the chip address, two or four data bytes may be received.
The first and third data bytes contain a function bit, which lets the IC distinguish between frequency
information and control information. If the function bit is a logic 1, the two following bytes contain control
information. The first data byte after the chip address, may be byte CO or byte FM. The two bytes of
frequency information are preceded by a logic 0.
20
SDA
SCL
STA
•
•
If three data bytes are received, the third one is ignored.
If five or more data bytes are received, the fifth and following ones are ignored, and the last ACK
pulse is sent at the end of the fourth data byte.
1 1 0 0 1 0 1 0 (ACK) = $CA (hex) in write mode
Example 1
Example 2
Example 3
Example 4
With:
STA = Start condition
FM = Frequency information, high order bits
C1 = Control information, high order bits
STO = Stop condition
2
C Write Mode Format and Bus Receiver
1
Chip Address ($CA)
2
3
4
STA
STA
STA
STA
5
2
2
C Compatible Bus Format
C compatible data format. The chip address (I
6
7
MC44BC374T1 Technical Data
CA
CA
CA
CA
8
ACK
9 10
First Data Byte (C1 or FM)
FM
FM
C1
C1
11 12 13
CA = Chip Address
FL = Frequency information, low order bits
CO = Control information, low order bits
C0
C0
FL
FL
14
15
STO
STO
FM
C1
16 17 18
ACK
C0
FL
2
C bus) is:
19
Data
STO
STO
44
ACK
45
MOTOROLA
Stop