DS90UB903Q Datasheet, PDF (29/41 Pages) Texas Instruments – 10 - 43MHz 18 Bit Color FPD-Link III Serializer and Deserializer with Bidirectional Control Channel

CAMERA MODE OPERATION
In Camera mode, I²C transactions originate from the Deseri-
alizer from the Master controller (Figure 28). The I²C 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 bidirectional control channel to initiate the trans-
actions. The Serializer will receive the command and gener-
ate an I²C transaction on its local I²C bus. At the same time,
the Serializer will capture the response on the I²C 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 I²C bus.
To configure the devices for camera mode operation, set the
Serializer MODE pin to Low and the Deserializer MODE pin
to High. Before initiating any I²C commands, the Deserializer
needs to be programmed with the target slave device ad-
dresses and Serializer device address. SER_DEV_ID Regis-
ter 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 regis-
ters values, the I²C slave will acknowledge the transaction to
the I²C master allowing reads or writes to target device.
FIGURE 28. Typical Camera System Diagram
30125440
DISPLAY MODE OPERATION
In Display mode, I²C transactions originate from the controller
attached to the Serializer. The I²C slave core in the Serializer
will detect if a transaction targets (local) registers within the
Serialier or the (remote) registers within the Deserializer or a
remote slave connected to the I²C master interface of the De-
serializer. Commands are sent over the forward channel link
to initiate the transactions. The Deserializer will receive the
command and generate an I²C transaction on its local I²C
bus. At the same time, the Deserializer will capture the re-
sponse on the I²C bus and return the response as a command
on the bidirectional control channel. The Serializer parses the
response and passes the appropriate response to the Serial-
izer I²C bus.
The physical device ID of the I²C slave in the Serializer is
determined by the analog voltage on the ID[x] input. It can be
reprogrammed by using the SER_DEV_ID register and set-
ting the bit . The device ID of the logical I²C slave in the
Deserializer is determined by programming the DES ID in the
Serializer. The state of the ID[x] input on the Deserializer is
used to set the device ID. The I²C 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 MODE pin to High and the Deserializer MODE pin
to Low. Before initiating any I²C 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 I²C
slave address matches any of registers values, the I²C slave
will acknowledge the transaction allowing read or write to tar-
get device. Note: In Display mode operation, registers
0x08h~0x17h on Deserializer must be reset to 0x00.
PROGRAMMABLE CONTROLLER
An integrated I²C slave controller is embedded in each of the
DS90UB903Q Serializer and DS90UB904Q Deserializer. It
must be used to access and program the extra features em-
bedded within the configuration registers. Refer to Table 1
and Table 2 for details of control registers.
I²C PASS THROUGH
I²C pass-through provides an alternative means to indepen-
dently address slave devices. The mode enables or disables
I²C bidirectional control channel communication to the remote
I²C bus. This option is used to determine whether or not an
I²C instruction is to be transferred over to the remote I²C de-
vice. When enabled, the I²C bus traffic will continue to pass
through and will be received by I²C devices downstream. If
disabled, I²C commands will be excluded to the remote I²C
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.
SYNCHRONIZING MULTIPLE LINKS
For applications requiring synchronization across multiple
links, it is recommended to utilize the General Purpose Input/
Output (GPI/GPO) pins to transmit control signals to synchro-
nize slave peripherals together. To synchronize the periph-
erals properly, the system controller needs to provide a sync
signal output. Note this form of synchronization timing rela-
tionship has a non-deterministic latency. After the control data
is reconstructed from the birectional control channel, there will
be a time variation of the GPI/GPO signals arriving at the dif-
ferent target devices (between the parallel links). The maxi-
mum latency delta (t1) of the GPI/GPO data transmitted
across multiple links is 25 us.
29
www.ti.com