Analog Devices EV-21569-SOM Manual page 21

Software-Controlled Switches (SoftConfig)
GPIO Register
GPIOB
• By default, the Microchip MCP23017 GPIO signals function as input signals.
The signals must be programmed as output signals to override their default values. A zero is programmed into
the register to enable the signal as an output. The following table shows the Microchip GPIO expander register
addresses.
IODIR Register
IODIRA
IODIRB
Each example in the Board Support Package (BSP) includes source files that program the soft switches, even if the
default settings are being used. The README for each example identifies only the signals that are being changed
from their default values. The code that programs the soft switches is located in the SoftConfig_XXX.c file in
each example, where XXX is the name of the baord.
2
The I C Hardware Address (0x21) and I
the two Microchip MCP23017 devices.
2
Table 3-2: I C Hardware Address (0x21)
GPIO
GPIOA
GPIOB
2
Table 3-3: I C Hardware Address (0x22)
GPIO
GPIOA
GPIOB
The board schematic shows how the two Microchip GPIO expanders are connected to the board's ICs.
The Output Signals of Microchip GPIO Expander (U13 Port A) and Output Signals of Microchip GPIO Expander
(U13 Port B) tables show the output signals of the Microchip GPIO expander (U13), with a TWI address of 0100
001X, where X represents the read or write bit. The signals that control an individual FET have an entry in the
FET column. The Component Connected column shows the board IC that is connected if the FET is enabled. The
Microchip (U13) is controlling the enable signal of a FET switch. Also note that if a particular functionality of the
processor signal is being used, it is in bold font in the Processor Signal column.
3–6
Register Address
0x13
IODIR Register Address
0x00
0x01
2
C Hardware Address (0x22) tables outline the default values for each of
MCP23017 Register Address
0x12
0x13
MCP23017 Register Address
0x12
0x13
Default Value
0x02
0xC4
Default Value
0xE0
0xFF
EV-21569-SOM
®
Manual