AT32UC3L064-D3HES ATMEL [ATMEL Corporation], AT32UC3L064-D3HES Datasheet - Page 191

• Manufacturer Part Number: AT32UC3L064-D3HES
• Manufacturer: ATMEL [ATMEL Corporation]

14.4.2
14.4.3
14.4.4
14.5
14.5.1
32099D–06/2010
Functional Description
Interrupt
Debug Operation
Clocks
Oscillator (OSC0) operation
with GPIO. When oscillators are used, the related pins are controlled directly by the SCIF, over-
riding GPIO settings.
The SCIF interrupt request line is connected to the interrupt controller. Using the SCIF interrupt
requires the interrupt controller to be programmed first.
The SCIF module does not interact with debug operations.
The SCIF controls all oscillators on the part. Those oscillators can then be used as sources for
for generic clocks (handled by the SCIF) and for the CPU and peripherals. (In this case, selec-
tion of source is done by the Power Manager.)
The main oscillator (OSC0) is designed to be used with an external 3 to 16MHz crystal and two
biasing capacitors, as shown in
Characteristics chapter. The oscillator can be used 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 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 configured to use an
external clock, the clock must be applied to the XIN pin while the XOUT pin can be used as a
general purpose I/O.
The oscillator can be enabled by writing to the OSCEN bits in OSCCTRL0. Operation mode
(external clock or crystal) is chosen by writing to the MODE field in OSCCTRL0. The oscillator is
automatically switched off in certain sleep modes to reduce power consumption, as described in
the Power Manager chapter.
After a hard reset, or when waking up from a sleep mode that disabled the oscillator, the oscilla-
tor may need a certain amount of time to stabilize on the correct frequency. This start-up time
can be set in the OSCCTRL0 register.
The SCIF masks the oscillator outputs during the start-up time, to ensure that no unstable clocks
propagate to the digital logic. The OSC0RDY bits in PCLKSR are automatically set and cleared
according to the status of the oscillators. A zero to one transition on these bits can also be con-
figured to generate an interrupt, as described in
Section 14.5.4 on page
Figure
197.
14-1. Capacitor values can be found in the Electrical
Section
14.6.1.
AT32UC3L016/32/64
191