AD9985/PCB AD [Analog Devices], AD9985/PCB Datasheet - Page 27

• Manufacturer Part Number: AD9985/PCB
• Description: 110 MSPS/140 MSPS Analog Interface for Flat Panel Displays
• Manufacturer: AD [Analog Devices]

Data is read from the control registers of the AD9985 in a
similar manner. Reading requires two data transfer operations:
The base address must be written with the R/W bit of the slave
address byte low to set up a sequential read operation.
Reading (the R/ W bit of the slave address byte high) begins at
the previously established base address. The address of the read
register autoincrements after each byte is transferred.
To terminate a read/write sequence to the AD9985, a stop signal
must be sent. A stop signal comprises a low-to-high transition
of SDA while SCL is high.
A repeated start signal occurs when the master device driving
the serial interface generates a start signal without first
generating a stop signal to terminate the current communi-
cation. This is used to change the mode of communication
(read, write) between the slave and master without releasing the
serial interface lines.
Serial Interface Read/Write Examples
Write to one control register
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Write to four consecutive control registers
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Start Signal
Slave Address Byte (R/ W Bit = Low)
Base Address Byte
Data Byte to Base Address
Stop Signal
Start Signal
Slave Address Byte (R/ W Bit = Low)
Base Address Byte
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Read from one control register
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Read from four consecutive control registers
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SCL
SDA
Data Byte to Base Address
Data Byte to (Base Address + 1)
Data Byte to (Base Address + 2)
Data Byte to (Base Address + 3)
Stop Signal
Start Signal
Slave Address Byte (R/ W Bit = Low)
Base Address Byte
Start Signal
Slave Address Byte (R/ W Bit = High)
Data Byte from Base Address
Stop Signal
Start Signal
Slave Address Byte (R/ W Bit = Low)
Base Address Byte
Start Signal
Slave Address Byte (R/ W Bit = High)
Data Byte from Base Address
Data Byte from (Base Address + 1)
Data Byte from (Base Address + 2)
Data Byte from (Base Address + 3)
Stop Signal
BIT 7
Figure 13. Serial Interface—Typical Byte Transfer
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
AD9985
ACK