Datasheet
2017 Microchip Technology Inc. DS60001516A-page 349
SAM9G20
Figure 28-2: Application Block Diagram
28.3 Product Dependencies
28.3.1 Pin Multiplexing
Each pin is configurable, according to product definition as either a general-purpose I/O line only, or as an I/O line multiplexed with one or
two peripheral I/Os. As the multiplexing is hardware-defined and thus product-dependent, the hardware designer and programmer must
carefully determine the configuration of the PIO controllers required by their application. When an I/O line is general-purpose only, i.e. not
multiplexed with any peripheral I/O, programming of the PIO Controller regarding the assignment to a peripheral has no effect and only
the PIO Controller can control how the pin is driven by the product.
28.3.2 External Interrupt Lines
The interrupt signals FIQ and IRQ0 to IRQn are most generally multiplexed through the PIO Controllers. However, it is not necessary to
assign the I/O line to the interrupt function as the PIO Controller has no effect on inputs and the interrupt lines (FIQ or IRQs) are used only
as inputs.
28.3.3 Power Management
The Power Management Controller controls the PIO Controller clock in order to save power. Writing any of the registers of the user inter-
face does not require the PIO Controller clock to be enabled. This means that the configuration of the I/O lines does not require the PIO
Controller clock to be enabled.
However, when the clock is disabled, not all of the features of the PIO Controller are available. Note that the Input Change Interrupt and
the read of the pin level require the clock to be validated.
After a hardware reset, the PIO clock is disabled by default.
The user must configure the Power Management Controller before any access to the input line information.
28.3.4 Interrupt Generation
For interrupt handling, the PIO Controllers are considered as user peripherals. This means that the PIO Controller interrupt lines are con-
nected among the interrupt sources 2 to 31. Refer to the PIO Controller peripheral identifier in the product description to identify the inter-
rupt sources dedicated to the PIO Controllers.
The PIO Controller interrupt can be generated only if the PIO Controller clock is enabled.
On-Chip Peripherals
PIO Controller
On-Chip Peripheral Drivers
Control & Command
Driver
Keyboard Driver
Keyboard Driver General Purpose I/Os External Devices