Datasheet

17. SYSCTRL – System Controller
17.1 Overview
The System Controller (SYSCTRL) provides a user interface to the clock sources, brown out detectors,
on-chip voltage regulator and voltage reference of the device.
Through the interface registers, it is possible to enable, disable, calibrate and monitor the SYSCTRL sub-
peripherals.
All sub-peripheral statuses are collected in the Power and Clocks Status register (PCLKSR). They can
additionally trigger interrupts upon status changes through the INTENSET (INTENSET), INTENCLR
(INTENCLR) and INTFLAG (INTFLAG) registers.
Additionally, BOD33 and BOD12 interrupts can be used to wake up the device from Stand-by mode upon
a programmed brown-out detection.
17.2 Features
• 0.4-32MHz Crystal Oscillator (XOSC)
– Tunable gain control
– Programmable start-up time
– Crystal or external input clock on XIN I/O
• 32.768kHz Crystal Oscillator (XOSC32K)
– Automatic or manual gain control
– Programmable start-up time
– Crystal or external input clock on XIN32 I/O
• 32.768kHz High Accuracy Internal Oscillator (OSC32K)
– Frequency fine tuning
– Programmable start-up time
• 32.768kHz Ultra Low-Power Internal Oscillator (OSCULP32K)
– Ultra low-power, always-on oscillator
– Frequency fine tuning
– Calibration value loaded from Flash Factory Calibration at reset
• 8MHz Internal Oscillator (OSC8M)
– Fast startup
– Output frequency fine tuning
– 4/2/1MHz divided output frequencies available
– Calibration value loaded from Flash Factory Calibration at reset
• Digital Frequency Locked Loop (DFLL48M)
– Internal oscillator with no external components
– 48MHz output frequency
– Operates standalone as a high-frequency programmable oscillator in Open-Loop mode
– Operates as an accurate frequency multiplier against a known frequency in Closed-Loop
mode
SAM D21 Family
SYSCTRL – System Controller
© 2018 Microchip Technology Inc.
Datasheet Complete
DS40001882D-page 172