Information
Section Number Title Page
24.4.5 MCG Fixed frequency clock .......................................................................................................................450
24.4.6 MCG PLL clock ..........................................................................................................................................451
24.4.7 MCG Auto TRIM (ATM)............................................................................................................................451
24.5 Initialization / Application information........................................................................................................................452
24.5.1 MCG module initialization sequence...........................................................................................................452
24.5.2 Using a 32.768 kHz reference......................................................................................................................454
24.5.3 MCG mode switching..................................................................................................................................455
Chapter 25
Oscillator (OSC)
25.1 Introduction...................................................................................................................................................................465
25.2 Features and Modes......................................................................................................................................................465
25.3 Block Diagram..............................................................................................................................................................466
25.4 OSC Signal Descriptions..............................................................................................................................................466
25.5 External Crystal / Resonator Connections....................................................................................................................467
25.6 External Clock Connections.........................................................................................................................................468
25.7 Memory Map/Register Definitions...............................................................................................................................469
25.7.1 OSC Memory Map/Register Definition.......................................................................................................469
25.8 Functional Description..................................................................................................................................................470
25.8.1 OSC Module States......................................................................................................................................471
25.8.2 OSC Module Modes.....................................................................................................................................472
25.8.3 Counter.........................................................................................................................................................474
25.8.4 Reference Clock Pin Requirements.............................................................................................................474
25.9 Reset..............................................................................................................................................................................474
25.10 Low Power Modes Operation.......................................................................................................................................475
25.11 Interrupts.......................................................................................................................................................................475
Chapter 26
RTC Oscillator
26.1 Introduction...................................................................................................................................................................477
26.1.1 Features and Modes.....................................................................................................................................477
K20 Sub-Family Reference Manual, Rev. 2, Feb 2012
Freescale Semiconductor, Inc. 19