ML6461
FUNCTIONAL DESCRIPTION (Continued)
PRESET PIN CONTROL
The ML6461 can be controlled by a pair of preset mode
pins. These pins do not allow access to all of the
programmable features of the ML6461, but are intended to
provide a simpler interface for most applications. Refer to
Table 8 for preset modes.
SERIAL BUS OPERATION
The serial bus control in the ML6461 has two levels of
addressing: Device Addressing and Functional Addressing.
Device Addressing: Figures 15, 16, and 17 show the
physical waveforms generated in order to address the
ML6461. There are six basic parts of the waveform:
1. Start Indication: Clock Cycle 0
2. Device Address Shifted in: Clock Cycle 1 through 8
3. Device Address Strobed and Decoded: Clock Cycle 9
4. Function Address Shifted in: Clock Cycle 10 through 17
5. Function Address Strobed and Decoded: Clock Cycle 18
6. Data Shifted in 8 bits at a time, MSB first: Clock
Cycle 19 through 26
7. Data Shifted: Clock Cycle 27
8. Repeat strep 6 & 7 until all data is clocked in.
9. Stop indication: After Last Clock Cycle
(54 for CC, 54 for CNTR)
Note: data at SDATA is ignored at steps 3, 5, and 7.
Device & Function Addressing: Figures 15, 16, an17
show the register address procedure of the ML6461.
Device Address (8 bit)
1011 0100 (Hex = B4)
Function Address (8 bit)
Closed Caption Data Registers (CC): 0000 0000 (Hex = 00)
Control Registers (CNTR): 0000 0011 (Hex = 03)
Number of Data Bits
Closed Caption Data Registers (CC): 4 x 8 bits
Control Registers (CNTR): 4 x 8 bits
CONTROL REGISTER DEFAULT SETTINGS
At Power up, the ML6461 default settings are as follows:
• Control Register is undefined when the serial
bus mode is enabled.
• Chip is ready to process video
• Preset Pins are available and if used will
configure the control register.
• Must write logic “0” (zero) to A30 to get
video
To get black at power up will require logic “1” in A30.
MODE
PRESET1
PRESET0
CC
A
0
0
XX
B
0
1
XX
C
1
0
XX
D
1
X = don't care
1
XX
CNTR
XXXXXXXX
09080209
1C080209
11080209
Mode Description
Mode A: All register contents are programmed through serial interface.
Mode B: Master mode, CCIR656 rate, analog blanking.
Mode C: Slave mode, SAV and EAV codes, CCIR656 rate, digital blanking.
Mode D: Slave mode, external sync at start of line, Square pixel rate, analog blanking
Table 8. Preset Modes and Register Values
24