Datasheet

245
32142D–06/2013
ATUC64/128/256L3/4U
14.4.1 I/O Lines
The SCIF provides a number of generic clock outputs, which can be connected to output pins,
multiplexed with GPIO lines. The programmer must first program the GPIO controller to assign
these pins to their peripheral function. If the I/O pins of the SCIF are not used by the application,
they can be used for other purposes by the GPIO controller. Oscillator pins are also multiplexed
with GPIO. When oscillators are used, the related pins are controlled directly by the SCIF, over-
riding GPIO settings.
RC32OUT will be output after reset, and the GPIO controller can assign this pin to other periph-
eral function after start-up.
14.4.2 Power Management
The BODs and all the oscillators, except the 32KHz oscillator (OSC32K) are turned off in some
sleep modes and turned automatically on when the device wakes up. The Voltage Regulator is
set in low power mode in some sleep modes and automatically set back in normal mode when
the device wakes up. Please refer to the Power Manager chapter for details.
The BOD control registers will not be reset by the Power Manager on a BOD reset.
14.4.3 Clocks
The SCIF controls all oscillators in the device. The oscillators can be used as source for the CPU
and peripherals. Selection of source is done in the Power Manager. The oscillators can also be
used as source for generic clocks.
14.4.4 Interrupts
The SCIF interrupt request line is connected to the interrupt controller. Using the SCIF interrupt
requires the interrupt controller to be programmed first.
14.4.5 Debug Operation
The SCIF does not interact with debug operations.
14.5 Functional Description
14.5.1 Oscillator (OSC) Operation
Rev: 1.1.1.0
The main oscillator (OSCn) is designed to be used with an external 0.450 to 16MHz crystal and
two biasing capacitors, as shown in the Electrical Characteristics chapter, or with an external
clock connected to the XIN. The oscillator can be used as source for the main clock in the
device, as described in the Power Manager chapter. The oscillator can be used as source for the
generic clocks, as described in the Generic Clocks section.
The oscillator is disabled by default after reset. When the oscillator is disabled, the XIN and
XOUT pins can be used as general purpose I/Os. When the oscillator is enabled, the XIN and
XOUT pins are controlled directly by the SCIF, overriding GPIO settings. When the oscillator is
configured to use an external clock, the clock must be applied to the XIN pin while the XOUT pin
can be used as general purpose I/O.
The oscillator is enabled by writing a one to the Oscillator Enable bit in the Oscillator Control reg-
ister (OSCCTRLn.OSCEN). Operation mode (external clock or crystal) is selected by writing to
the Oscillator Mode bit in OSCCTRLn (OSCCTRLn.MODE). The oscillator is automatically dis-