Information
Section Number Title Page
24.4.3 MCG Internal Reference Clocks..................................................................................................................543
24.4.4 External Reference Clock............................................................................................................................544
24.4.5 MCG Fixed Frequency Clock .....................................................................................................................544
24.4.6 MCG PLL Clock .........................................................................................................................................545
24.4.7 MCG Auto TRIM (ATM)............................................................................................................................545
24.5 Initialization / Application Information........................................................................................................................546
24.5.1 MCG Module Initialization Sequence.........................................................................................................546
24.5.2 Using a 32.768 kHz Reference....................................................................................................................548
24.5.3 MCG Mode Switching.................................................................................................................................549
Chapter 25
Oscillator (OSC)
25.1 Introduction...................................................................................................................................................................559
25.2 Features and Modes......................................................................................................................................................559
25.3 Block Diagram..............................................................................................................................................................560
25.4 OSC Signal Descriptions..............................................................................................................................................560
25.5 External Crystal / Resonator Connections....................................................................................................................561
25.6 External Clock Connections.........................................................................................................................................562
25.7 Memory Map/Register Definitions...............................................................................................................................563
25.7.1 OSC Memory Map/Register Definition.......................................................................................................563
25.8 Functional Description..................................................................................................................................................564
25.8.1 OSC Module States......................................................................................................................................564
25.8.2 OSC Module Modes.....................................................................................................................................566
25.8.3 Counter.........................................................................................................................................................568
25.8.4 Reference Clock Pin Requirements.............................................................................................................568
25.9 Reset..............................................................................................................................................................................568
25.10 Low Power Modes Operation.......................................................................................................................................569
25.11 Interrupts.......................................................................................................................................................................569
K20 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc. 21