mc68hc908sr12 Freescale Semiconductor, Inc, mc68hc908sr12 Datasheet - Page 102

• Manufacturer Part Number: mc68hc908sr12
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Oscillator (OSC)
7.2 Introduction
Data Sheet
102
The oscillator module provides the reference clock for the clock
generator module (CGM), the timebase module (TBM), and other MCU
sub-systems.
The oscillator module consist of three types of oscillator circuits:
The reference clock for the CGM and other MCU sub-systems is
selected by:
The reference clock for the timebase module (TBM) is selected by the
two bits, OSCCLK1 and OSCCLK0, in the CONFIG2 register.
The internal oscillator runs continuously after a POR or reset, and is
always available. The RC and crystal oscillator cannot run concurrently;
one is disabled while the other is selected; because the RC and x-tal
circuits share the same OSC1 pin.
Figure
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Internal oscillator
RC oscillator
Crystal (x-tal) oscillator
MC68HC908SR12 — FLASH device — oscillator selected by
programming the mask option register located at $FF80.
MC68HC08SR12 — ROM device — oscillator selected by ROM-
mask layer at factory.
7-1. shows the block diagram of the oscillator module.
Oscillator (OSC)
MC68HC908SR12•MC68HC08SR12 — Rev. 5.0
Freescale Semiconductor