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AN1043 Schematic ( PDF Datasheet ) - Microchip

Teilenummer AN1043
Beschreibung Unique Features of the MCP23X08/17 GPIO Expanders
Hersteller Microchip
Logo Microchip Logo 




Gesamt 10 Seiten
AN1043 Datasheet, Funktion
AN1043
Unique Features of the MCP23X08/17 GPIO Expanders
Author: Pat Richards
Microchip Technology Inc.
INTRODUCTION
GPIO expanders provide easy I/O expansion using
standard serial interfaces. GPIO products are used to
increase the I/O on an MCU or provide remote I/O
using a serial interface.
This application note discusses the feature set and use
of the MCP23X08/17 (8-bit and 16-bit) GPIO Expand-
ers.
The MCP23X08 are 8-bit GPIO Expanders:
• MCP23008: I2C™ Interface
• MCP23S08: SPI Interface
The MCP23X17 are 16-bit GPIO Expanders:
• MCP23017: I2C Interface
• MCP23S17: SPI Interface
The functions and features of the MCP23X08 and
MCP23X17 are basically the same, except where
otherwise noted.
FEATURES
This application note discusses some of the features of
the MCP23X08/17 and how they may be used in an
application:
• I/O Port Description
• 8/16-Bit Mode (MCP23X17 only)
• Interrupt Features
- Mapping Interrupts
- Mirroring Interrupts (MCP23X17 only)
- Servicing Interrupts
• Internal Address Pointer Control
• Hardware Address Pin on SPI
I/O PORT DESCRIPTION
The I/O port is highly configurable for maximum
flexibility. Figure 1 is a simplified block diagram of an
I/O port pin. The port can either drive logic levels on the
pin, or read logic levels from the pad. The level on the
pad can be read at any time, regardless if the pin is
configured as an input or an output.
The IODIR register controls the direction of the pins
(input or output). More specifically, the IODIR registers
simply enables/disables the output driver. When the
driver is activated (IODIR = 0), the pad is driven to the
state in the latch register (OLAT). When deactivated
(IODIR = 1), the driver is high impedance.
The I/O port has multiple, individual configurations.
Each pin can
be configured as an input. The output driver is
disabled (high impedance)
be configured as an output. The output driver
is enabled and the value in the latch is driven on
the pin.
enable a weak pull-up resistor
emulate an open-drain configuration. This is
accomplished by clearing the output latch (OLAT)
bit to a zero and using the direction register
(IODIR) to set the level on the pin. A pull-up
resistor is required to pull the pin to voltage when
the pin is an input
- To drive a 0: configure the pin as an output
(IODIR = 0) so the port drives whatever is in
OLAT (logic 0 in this case)
- To float a 1: set the pin as an input
(IODIR = 1). The output driver is disabled
and the pull-up resistor pulls the pin to a
logic 1
© 2006 Microchip Technology Inc.
DS01043A-page 1
Free Datasheet http://www.datasheet4u.com/






AN1043 Datasheet, Funktion
AN1043
FIGURE 6:
8-BIT MODE: ADDRESS POINTER ENABLED (MCP23008 EXAMPLE)
When the address pointer is ENABLED and the device is in
8-bit mode, the address pointer will increment after every
byte is clocked. The address pointer will roll over to 00h
after exceeding 1Ah (which is the last location of Port B).
S 0100aaa0A 00001010A 10101010A 01010101A 10101010P
MCP23X08
Opcode
Register
Addr = 09h
Data @
09h
Data @
0Ah
Data @
10h
GPIOA
OLATA
IODIRB
IPOLB
GPINTENB
DEFVALB
INTCONB
IOCON
GPPUB
INTFB
INTCAPB
GPIOB
OLATB
09
0A
10
11
12
13
14
15
16
17
18
19
1A
Note: The address pointer jumps
from 0Ah to 10h when transitioning
from Port A to Port B
FIGURE 7:
16-BIT MODE: ADDRESS POINTER DISABLED (MCP23017 EXAMPLE)
When the address pointer is DISABLED and the device is in
16-bit mode, the address pointer will alternate between the
register pair. Also, the initial address can be either register
address (e.g., 14h or 15h) and the pointer will still alternate
between the registers.
S 0100aaa0A 00010010A 10101010A 01010101A 10101010P
MCP23X17
Opcode
Register
Addr = 12h
Data @
12h
Data @
13h
Data @
12h
INTCONB
IOCON
IOCON
GPPUA
GPPUB
INTFA
INTFB
INTCAPA
INTCAPB
GPIOA
GPIOB
OLATA
OLATB
09
0A
0B
0C
0D
0E
0F
10
11
12
13
14
15
DS01043A-page 6
© 2006 Microchip Technology Inc.
Free Datasheet http://www.datasheet4u.com/

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