Figure 3-5:
Example of a Mechanical Switch (Equivalent to Example of Bus Switch)
SoftConfig on the Board
Two Microchip MCP23017 GPIO expanders provide control for individual electronic switches. The TWI2 inter-
face of the processor communicates with the Microchip devices. There are individual switches with default settings
that enable basic board functionality.
The
Default Processor Interface Availability
table lists the processor and board interfaces that are available by de-
fault. Note that only interfaces affected by software switches are listed in the table.
Table 3-1:
Default Processor Interface Availability
Interface
Availability by Default
UART0
USB to UART FTDI232RQ
SPI Flash
Quad mode enabled
LEDs
Enabled
Programming SoftConfig Switches
On the board, two Microchip MCP23017 devices exist. Each of these devices has the following programming char-
acteristics:
•
Each GPIO register controls eight signals (software switches).
GPIO Register
Register Address
GPIOA
0x12
Software-Controlled Switches (SoftConfig)
EV-21569-SOM
®
Manual
3–5
Summary of Contents for EV-21569-SOM
Page 31: ...EV 21569 SOM Manual 16...
