Datasheet

30 Maxim Integrated
Gigabit Multimedia Serial Link with Spread
Spectrum and Full-Duplex Control Channel
MAX9259/MAX9260
Figure 24. UART Protocol for Base Mode
Figure 25. UART Data Format for Base Mode
Figure 26. SYNC Byte (0x79) Figure 27. ACK Byte (0xC3)
assume there was an error in the packet transmission or
response. In base mode, the FC must keep the UART Tx/
Rx lines high no more than four bit times between bytes
in a packet. Keep the UART Tx/Rx lines high for at least
16 bit times before starting to send a new packet.
As shown in Figure 28, the remote-side device converts
the packets going to or coming from the peripherals from
the UART format to the 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’s data rate is the same as the UART data rate.
Interfacing Command-Byte-Only
I
2
C Devices
The MAX9259/MAX9260 UART-to-I
2
C conversion inter-
faces with devices that do not require register address-
es, such as the MAX7324 GPIO expander. 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. In this mode, the I
2
C master ignores the reg-
ister address byte and directly reads/writes the subse-
quent data bytes (Figure 29).
WRITE DATA FORMAT
SYNC DEV ADDR + R/W REG ADDR NUMBER OF BYTES
SYNC DEV ADDR + R/W REG ADDR NUMBER OF BYTES BYTE 1 BYTE N
ACK
BYTE NBYTE 1ACK
MASTER READS FROM SLAVE
READ DATA FRMAT
MASTER WRITES TO SLAVE
MASTER WRITES TO SLAVE
MASTER READS FROM SLAVE
START D0 D1 D2 D3 D4 D5 D6 D7 PARITY STOP
1 UART FRAME
FRAME 1
FRAME 2 FRAME 3
STOP START STOP START
BASE MODE USES EVEN PARITY
START
D0
10011110
D1 D2 D3 D4 D5 D6 D7
PARITY STOP
START
D0
11000011
D1 D2 D3 D4 D5 D6 D7
PARITY STOP