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| XRA1200 Datasheet, PDF (6/16 Pages) Exar Corporation – 8-BIT I2C/SMBUS GPIO EXPANDER | |||
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XRA1200/1200P
8-BIT I2C/SMBUS GPIO EXPANDER
REV. 1.0.0
1.1.2 I2C Read and Write
A read or write transaction is determined by bit-0 of the slave address. If bit-0 is â0â, then it is a write
transaction. If bit-0 is â1â, then it is a read transaction.
1.1.3 I2C Command Byte
An I2C command byte is sent by the I2C master following the slave address. The command byte indicates the
address offset of the register that will be accessed. Table 2 below lists the command bytes for each register.
TABLE 2: I2C COMMAND BYTE (REGISTER ADDRESS)
COMMAND BYTE
REGISTER NAME DESCRIPTION
READ/WRITE
DEFAULT VALUES
0x00
GSR - GPIO State
Read-Only
0xXX
0x01
OCR - Output Control
Read/Write
0xFF
0x02
PIR - Input Polarity Inversion
Read/Write
0x00
0x03
GCR - GPIO Configuration
Read/Write
0xFF
0x04
PUR - Input Internal Pull-up Resistor Enable/Disable
Read/Write
0x00 (XRA1200)
0xFF (XRA1200P)
0x05
IER - Input Interrupt Enable
Read/Write
0x00
0x06
TSCR - Output Three-State Control
Read/Write
0x00
0x07
ISR - Input Interrupt Status
Read
0x00
0x08
REIR - Input Rising Edge Interrupt Enable
Read/Write
0x00
0x09
FEIR - Input Falling Edge Interrupt Enable
Read/Write
0x00
0x0A
IFR - Input Filter Enable/Disable
Read/Write
0xFF
6
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