Datasheet

DS92LX2121, DS92LX2122
www.ti.com SNLS330I –MAY 2010–REVISED APRIL 2013
CAMERA MODE OPERATION
In Camera mode, I
2
C transactions originate from the Deserializer from the host controller. The I
2
C slave core in
the Deserializer will detect if a transaction is intended for the Serializer or a slave at the Serializer. Commands
are sent over the bi-directional control channel to initiate the transactions. The Serializer will receive the
command and generate an I
2
C transaction on its local I
2
C bus. At the same time, the Serializer will capture the
response on the I
2
C bus and return the response as a command on the forward channel link. The Deserializer
parses the response and passes the appropriate response to the Deserializer I
2
C bus.
To configure the devices for camera mode operation, set the Serializer M/S pin to LOW and the Deserializer M/S
pin to HIGH. Before initiating any I
2
C commands, the Deserializer needs to be programmed with the target slave
device addresses and Serializer device address. SER_DEV_ID Register 0x07h sets the Serializer device
address and SLAVE_x_MATCH/SLAVE_x_INDEX registers 0x08h~0x17h set the remote target slave addresses.
The slave address match registers must also be set. In slave mode the address register is compared with the
address byte sent by the I2C master. If the addresses are equal to any of registers values, the I
2
C slave will
acknowledge the transaction to the I
2
C master allowing reads or writes to target device.
DISPLAY MODE OPERATION
In Display mode, I
2
C transactions originate from the controller attached to the Serializer. The I
2
C slave core in
the Serializer will detect if a transaction targets (local) registers within the Serializer or the (remote) registers
within the Deserializer or a remote slave connected to the I
2
C master interface of the Deserializer. Commands
are sent over the forward channel link to initiate the transactions. The Deserializer will receive the command and
generate an I
2
C transaction on its local I
2
C bus. At the same time, the Deserializer will capture the response on
the I
2
C bus and return the response as a command on the bi-directional control channel. The Serializer parses
the response and passes the appropriate response to the Serializer I
2
C bus.
The physical device ID of the I
2
C slave in the Serializer is determined by the analog voltage on the CAD pin
input. It can be reprogrammed by using the SER_DEV_ID register and setting the bit . The device ID of the
logical I
2
C slave in the Deserializer is determined by programming the DES ID in the Serializer. The state of the
CAD pin input on the Deserializer is used to set the device ID. The I
2
C transactions between Ser/ Des will be
bridged between the host to the remote slave.
To configure the devices for display mode operation, set the Serializer M/S pin to HIGH and the Deserializer M/S
pin to LOW. Before initiating any I
2
C commands, the Serializer needs to be programmed with the target slave
device address and Serializer device address. DES_DEV_ID Register 0x06h sets the Deserializer device
address and SLAVE_DEV_ID register 0x7h sets the remote target slave address. If the I
2
C slave address
matches any of registers values, the I
2
C slave will acknowledge the transaction allowing read or write to target
device. Note: In Display mode operation, registers 0x08h~0x17h on Deserializer must be reset to 0x00.
PROGRAMMABLE CONTROLLER
An integrated I
2
C slave controller is embedded in each of the DS92LX2121 Serializer and DS92LX2122
Deserializer. It must be used to access and program the extra features embedded within the configuration
registers. Refer to Table 1 and Table 2 for details of control registers.
I
2
C PASS THROUGH
I
2
C pass-through provides an alternative means to independently address slave devices. The mode enables or
disables I
2
C bidirectional control channel communication to the remote I
2
C bus. This option is used to determine
whether or not an I
2
C instruction is to be transferred over to the remote I
2
C device. When enabled, the I
2
C bus
traffic will continue to pass through and will be received by I
2
C devices downstream. If disabled, I
2
C commands
will be excluded to the remote I
2
C device. The pass through function also provides access and communication to
only specific devices on the remote bus. The feature is effective for both Camera mode and Display mode.
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