Datasheet

© 2007 Microchip Technology Inc. DS20090C-page 9
MCP23016
1.7.4 I/O DIRECTION REGISTERS
Two registers control the direction of data I/O:
• IODIR0 (controls GP0)
• IODIR1 (controls GP1)
When a bit in these registers is set, the corresponding
pin becomes an input. Otherwise, it becomes an
output. At Power-on Reset, the device ports are
configured as inputs.
REGISTER 1-7: IODIR0 - I/O DIRECTION REGISTER 0
REGISTER 1-8: IODIR1 - I/O DIRECTION REGISTER 1
R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1
IOD0.7 IOD0.6 IOD0.5 IOD0.4 IOD0.3 IOD0.2 IOD0.1 IOD0.0
bit 7 bit 0
bit 7-0
IOD0.0:IO0.7: Controls the direction of data I/O
1 = Input
0 = Output
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown
R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1
IOD1.7 IOD1.6 IOD1.5 IOD1.4 IOD1.3 IOD1.2 IOD1.1 IOD1.0
bit 7 bit 0
bit 7-0
IOD1.0:IO1.7: Controls the direction of data I/O
1 = Input
0 = Output
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown