Atmel ARM-Based Evaluation Kit for SAM4S16C, 32-Bit ARM® Cortex® Microcontroller ATSAM4S-WPIR-RD ATSAM4S-WPIR-RD Data Sheet

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SAM4S Series [DATASHEET]

Atmel-11100G-ATARM-SAM4S-Datasheet_27-May-14

Each pin is configurable, depending on the product, 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. 

The interrupt signals FIQ and IRQ0 to IRQn are 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.

The Power Management Controller controls the PIO Controller clock in order to save power. Writing any of the 

registers of the user interface 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, including glitch 

filtering. Note that the input change interrupt, the interrupt modes on a programmable event 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. 

For interrupt handling, the PIO Controllers are considered as user peripherals. This means that the PIO Controller 

interrupt lines are connected among the interrupt sources. Refer to the PIO Controller peripheral identifier in the 

product description to identify the interrupt sources dedicated to the PIO Controllers. Using the PIO Controller 

requires the Interrupt Controller to be programmed first.
The PIO Controller interrupt can be generated only if the PIO Controller clock is enabled.