Clock Controller (Clkctrl); Features; Overview - Microchip Technology megaAVR 0 Series Manual

9.

Clock Controller (CLKCTRL)

9.1

Features

• All clocks and clock sources are automatically enabled when requested by peripherals
• Internal Oscillators:
– 20 MHz Oscillator (OSC20M)
– 32 KHz Ultra Low-Power Oscillator (OSCULP32K)
• External Clock Options:
– 32.768 kHz Crystal Oscillator (XOSC32K)
– External clock
• Main Clock Features:
– Safe run-time switching
– Prescaler with 1x to 64x division in 12 different settings
9.2

Overview

The Clock Controller peripheral (CLKCTRL) controls, distributes, and prescales the clock signals from the
available oscillators. The CLKCTRL supports internal and external clock sources.
The CLKCTRL is based on an automatic clock request system, implemented in all peripherals on the
device. The peripherals will automatically request the clocks needed. If multiple clock sources are
available, the request is routed to the correct clock source.
The Main Clock (CLK_MAIN) is used by the CPU, RAM, and the I/O bus. The main clock source can be
selected and prescaled. Some peripherals can share the same clock source as the main clock, or run
asynchronously to the main clock domain.
©
2018 Microchip Technology Inc.
Datasheet Preliminary
®
megaAVR 0-Series
Clock Controller (CLKCTRL)
DS40002015A-page 77