XRA1402IG16-0B Datasheet, PDF (5/14 Pages) Exar Corporation – 8-BIT SPI GPIO EXPANDER

XRA1402
REV. 1.0.0
8-BIT SPI GPIO EXPANDER
1.1.1 SPI Command Byte
An SPI command byte is sent by the SPI 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: 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
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
1.2 Interrupts
The table below summarizes the interrupt behavior of the different register settings for the XRA1402.
TABLE 3: INTERRUPT GENERATION AND CLEARING
GCR IER REIR FEIR IFR
BIT BIT BIT BIT BIT
INTERRUPT GENERATED BY:
INTERRUPT CLEARED BY:
1 0 X X X No interrupts enabled (default)
N/A
0 A rising or falling edge on the input
1 1 0 0 ^{1 A rising or falling edge on the input and}
remains in the new state for more than
1075ns
Reading the GSR register or if the input
changes back to its previous state (state of
input during last read to GSR)
0 A rising edge on the input
Reading the GSR register
1 1 1 0 _{1 A rising edge on the input and remains high}
for more than 1075ns
0 A falling edge on the input
Reading the GSR register
1 1 0 1 _{1 A falling edge on the input and remains low}
for more than 1075ns
0 A rising or falling edge on the input
Reading the GSR register
1 1 1 1 ^{1 A rising or falling edge on the input and}
remains in the new state for more than
1075ns
0 x x x x No interrupts in output mode
N/A
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