MAX9268GCMSLASHV+T datasheet(22/35 Pages) MAXIM

22 / 35 page

Gigabit Multimedia Serial Link Deserializer

with LVDS System Interface

22 _____________________________________________________________________________________

Interfacing Command-Byte-Only I2C Devices

The GMSL serializer and MAX9268 UART-to-I2C

conversion interfaces with devices that do not require

er. In this mode, the I2C master ignores the register

address byte and directly reads/writes the subsequent

data bytes (Figure 21). Change the communication

method of the I2C 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.

Bypass Mode

In bypass mode, the GMSL serializer/MAX9268 ignore

UART communications. The FC is thereby free to

communicate with the peripherals using its own UART

protocol without concern that communication traffic

inadvertently misprograms the GMSL serializer or

MAX9268. The FC cannot access the GMSL serializer/

MAX9268 registers in this mode. Peripherals accessed

through the forward control channel using the UART

interface need to handle at least one TXCLKOUT_ period

of jitter due to the asynchronous sampling of the UART

signal by TXCLKOUT_.

Set MS = high to put the control channel into bypass

mode. For applications with the FC connected to the

deserializer (CDS is high), 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

(CDS = low). Bypass mode accepts bit rates down to

28kbps in the forward direction (serializer to deserial-

izer), and 7.7kbps in the reverse direction (deserializer to

serializer). See the Interrupt Control section for interrupt

functionality limitations. The control-channel data pattern

should not be held low longer than 100µs if interrupt

control is used.

Interrupt Control

The INT pin of the GMSL serializer is the interrupt output

and the INT pin of the MAX9268 is the interrupt input.

The interrupt output on the GMSL serializer follows the

transitions at the interrupt input, even during reverse-

channel communication or loss of lock. This interrupt

function supports remote-side functions such as touch-

screen peripherals, remote power-up, or remote moni-

toring. Interrupts that occur during periods where the

reverse control channel is disabled, such as link startup/

shutdown, are automatically resent once the reverse

control channel becomes available again. Bit D4 of

input state. The INT output of the GMSL serializer is low

after power-up. In addition, the FC can set the INT output

of the serializer by writing to the SETINT register bit. In

normal operation, the state of the interrupt output

changes when the interrupt input on the MAX9268 toggles.

Do not send a logic-low value longer than 100Fs in

either base or bypass mode to ensure proper interrupt

functionality.

Figure 21. Format Conversion Between GMSL UART and I2C with Register Address (I2CMETHOD = 1)

: MASTER TO SLAVE

GMSL SERIALIZER/MAX9268

UART-TO-I2C CONVERSION OF READ PACKET (I2CMETHOD = 1)

UART-TO-I2C CONVERSION OF WRITE PACKET (I2CMETHOD = 1)

GMSL SERIALIZER/MAX9268

SYNC FRAME

DEVICE ID + RD

NUMBER OF BYTES

SYNC FRAME

DEVICE ID + WR

NUMBER OF BYTES

DATA 0

DATA N

ACK FRAME

DATA 0

DATA N

DATA 0

W A

DEV ID

A P

PERIPHERAL

1 1

DEV ID

R A

A P

DATA 0

DATA N

: SLAVE TO MASTER

S: START

P: STOP

A: ACKNOWLEDGE

MAX9268GCM/V+T Datasheet(PDF) 22 Page - Maxim Integrated Products

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