AD9883A
There are five components to serial bus operation:
Table XXXIV. Detected Coast Input Polarity Status
• Start Signal
Polarity Status
Result
• Slave Address Byte
• Base Register Address Byte
• Data Byte to Read or Write
• Stop Signal
0
1
Coast Polarity Negative
Coast Polarity Positive
This indicates that Bit 1 of Register 5 is the 4:2:2 Output
mode select bit.
When the serial interface is inactive (SCL and SDA are high)
communications are initiated by sending a start signal. The start
signal is a high-to-low transition on SDA while SCL is high.
This signal alerts all slaved devices that a data transfer sequence
is coming.
15
1
4:2:2 Output Mode Select
A bit that configures the output data in 4:2:2 mode.
This mode can be used to reduce the number of data
lines used from 24 down to 16 for applications using
YUV, YCbCr, or YPbPr graphics signals. A timing
diagram for this mode is shown in Figure 9.
The first eight bits of data transferred after a start signal com-
prise a 7-bit slave address (the first seven bits) and a single R/W
Bit (the eighth bit). The R/W Bit indicates the direction of data
transfer, read from (1) or write to (0) the slave device. If the
transmitted slave address matches the address of the device (set by
the state of the SA1-0 input pins in Table XXXIV, the AD9883A
acknowledges by bringing SDA low on the ninth SCL pulse. If the
addresses do not match, the AD9883A does not acknowledge.
Recommended input and output configurations are
shown in Table XXXV.
Table XXXV. 4:2:2 Output Mode Select
Select
Output Mode
0
1
4:2:2
4:4:4
Table XXXVII. Serial Port Addresses
Bit 7
A6
(MSB)
Bit 6 Bit 5
Bit 4
A3
Bit 3
A2
Bit 2
A1
Bit 1
A0
A5
A4
Table XXXVI. 4:2:2 Input/Output Configuration
Input
1
1
0
0
0
0
1
1
1
1
0
0
0
1
Channel
Connection
Output Format
Red
Green
Blue
V
Y
U
U/V
Y
Data Transfer via Serial Interface
For each byte of data read or written, the MSB is the first bit of
the sequence.
High Impedance
If the AD9883A does not acknowledge the master device during
a write sequence, the SDA remains high so the master can gen-
erate a stop signal. If the master device does not acknowledge the
AD9883A during a read sequence, the AD9883A interprets this
as “end of data.” The SDA remains high so the master can
generate a stop signal.
2-WIRE SERIAL CONTROL PORT
A 2-wire serial interface control interface is provided. Up to two
AD9883A devices may be connected to the 2-wire serial interface,
with each device having a unique address.
The 2-wire serial interface comprises a clock (SCL) and a bidi-
rectional data (SDA) pin. The analog flat panel interface acts as
a slave for receiving and transmitting data over the serial interface.
When the serial interface is not active, the logic levels on SCL
and SDA are pulled high by external pull-up resistors.
Writing data to specific control registers of the AD9883A requires
that the 8-bit address of the control register of interest be written
after the slave address has been established. This control register
address is the base address for subsequent write operations. The
base address autoincrements by one for each byte of data written
after the data byte intended for the base address. If more bytes
are transferred than there are available addresses, the address will
not increment and remains at its maximum value of 14H. Any base
address higher than 14H will not produce an acknowledge signal.
Data received or transmitted on the SDA line must be stable for
the duration of the positive-going SCL pulse. Data on SDA must
change only when SCL is low. If SDA changes state while SCL
is high, the serial interface interprets that action as a start or
stop sequence.
SDA
tBUFF
tDSU
tDHO
tSTOSU
tSTASU
tSTAH
tDAL
SCL
tDAH
Figure 10. Serial Port Read/Write Timing
–22–
REV. B
ADI [ ADI ]
