Datasheet

MAX9273
22-Bit GMSL Serializer with Coax or
STP Cable Drive
26Maxim Integrated
As shown in Figure 22, the remote-side device converts
packets going to or coming from the peripherals from
UART format to I
2
C format and vice versa. The remote
device removes the byte number count and adds or
receives the ACK between the data bytes of I
2
C. The I
2
C
bit rate is the same as the UART bit rate.
Interfacing Command-Byte-Only I
2
C
Devices with UART
The serializer/deserializer UART-to-I
2
C conversion can
interface with devices that do not require register address-
es, such as the MAX7324 GPIO expander. In this mode,
the I
2
C master ignores the register address byte and
directly reads/writes the subsequent data bytes (Figure 23).
Change the communication method of the I
2
C master using
the I2CMETHOD bit. I2CMETHOD = 1 sets command-byte-
only mode, while I2CMETHOD = 0 sets normal mode where
the first byte in the data stream is the register address.
UART Bypass Mode
In bypass mode, the serializer/deserializer ignore UART
commands from the FC and the FC communicates with
the peripherals directly using its own defined UART pro-
tocol. The FC cannot access the serializer/deserializer
registers in this mode. Peripherals accessed through the
forward control channel using the UART interface need
to handle at least one PCLKIN period Q 10ns of jitter due
to the asynchronous sampling of the UART signal by
PCLKIN. Set MS = high to put the control channel into
bypass mode. For applications with the FC connected to
the deserializer, there is a 1ms wait time between setting
MS high and the bypass control channel being active.
There is no delay time when switching to bypass mode
when the FC is connected to the serializer. Do not send
a logic-low value longer than 100Fs to ensure proper
GPO functionality. Bypass mode accepts bit rates down
to 10kbps in either direction. See the GPO/GPI Control
section for GPO functionality limitations. The control-
channel data pattern should not be held low longer than
100Fs if GPO control is used.
Figure 22. Format Conversion Between GMSL UART and I
2
C with Register Address (I2CMETHOD = 0)
11
SYNC FRAME REGISTER ADDRESS NUMBER OF BYTESDEVICE ID + WR DATA 0
DEV ID A
11 11 11 11
DATA N
11 11
S
1 11
ACK FRAME
7
: MASTER TO SLAVE
8
SERIALIZER/DESERIALIZER PERIPHERAL
W
1
REG ADDR
8
A
1181
11
SYNC FRAME REGISTER ADDRESS NUMBER OF BYTESDEVICE ID + RD
11 11 11 11
ACK FRAME
DATA 0
11
DATA N
11
UART-TO-I
2
C CONVERSION OF WRITE PACKET (I2CMETHOD = 0)
UART-TO-I
2
C CONVERSION OF READ PACKET (I2CMETHOD = 0)
S: START P: STOP A: ACKNOWLEDGE
: SLAVE TO MASTER
DATA 0A DATA NAP
DEV ID AS
117
W
1
DEV ID AS
117
R
1
DATA NP
18
A
1
DATA 0
8
A
1
REG ADDR
8
A
1
FC
SERIALIZER/DESERIALIZER
FC
SERIALIZER/DESERIALIZER
SERIALIZER/DESERIALIZER PERIPHERAL