MCP23017 Datasheet, PDF (12/48 Pages) Microchip Technology – 16-Bit I/O Expander with Serial Interface

MCP23017/MCP23S17
1.6.1 I/O DIRECTION REGISTER
Controls the direction of the data I/O.
When a bit is set, the corresponding pin becomes an
input. When a bit is clear, the corresponding pin
becomes an output.
REGISTER 1-1: IODIR – I/O DIRECTION REGISTER (ADDR 0x00)
R/W-1
IO7
bit 7
R/W-1
IO6
R/W-1
IO5
R/W-1
IO4
R/W-1
IO3
R/W-1
IO2
R/W-1
IO1
R/W-1
IO0
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 7-0
IO7:IO0: These bits control the direction of data I/O <7:0>
1 = Pin is configured as an input.
0 = Pin is configured as an output.
DS21952B-page 12
© 2007 Microchip Technology Inc.