Atmel SAM4L Xplained Pro Starter Kit Atmel ATSAM4L-XSTK ATSAM4L-XSTK Data Sheet

42023E–SAM–07/2013

In order to use this module, other parts of the system must be configured correctly, as described
below.

If the CPU enters a sleep mode that disables clocks used by the GPIO, the GPIO will stop func-
tioning and resume operation after the system wakes up from sleep mode.

If a peripheral function is configured for a GPIO pin, the peripheral will be able to control the
GPIO pin even if the GPIO clock is stopped.

The GPIO is connected to a Peripheral Bus clock (CLK_GPIO). This clock is generated by the
Power Manager. CLK_GPIO is enabled at reset, and can be disabled by writing to the Power
Manager. CLK_GPIO must be enabled in order to access the configuration registers of the GPIO
or to use the GPIO interrupts. After configuring the GPIO, the CLK_GPIO can be disabled by
writing to the Power Manager if interrupts are not used.

The GPIO interrupt request lines are connected to the NVIC. Using the GPIO interrupts requires
the NVIC to be programmed first.

The GPIO peripheral events are connected via the Peripheral Event System. Refer to 

 for details.

When an external debugger forces the CPU into debug mode, the GPIO continues normal oper-
ation. If the GPIO is configured in a way that requires it to be periodically serviced by the CPU
through interrupts or similar, improper operation or data loss may result during debugging.

GPIOn

GPIO pin n

Digital