mc68hc908ap8a Freescale Semiconductor, Inc, mc68hc908ap8a Datasheet - Page 72

• Manufacturer Part Number: mc68hc908ap8a
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Oscillator (OSC)
5.2.1 CGM Reference Clock Selection
The clock generator module (CGM) reference clock (CGMXCLK) is the reference clock input to the MCU.
It is selected by programming two bits in a FLASH memory location; the mask option register (MOR), at
$FFCF. See
72
3.5 Mask Option Register
Address:
OSCSEL1
OSCSEL0
Erased:
Reset:
Read:
MOR
Write:
OSCSEL1 OSCSEL0
X-TAL OSCILLATOR
$FFCF
Bit 7
R
1
OSC1
Figure 5-1. Oscillator Module Block Diagram
To CGM and others
Figure 5-2. Mask Option Register (MOR)
= Reserved
X
XCLK
MC68HC908AP A-Family Data Sheet, Rev. 3
6
1
MUX
OSC2
CGMXCLK
RC
(MOR).
R
5
1
I
To CGM PLL
RC OSCILLATOR
CGMRCLK
Unaffected by reset
R
4
1
RCCLK
R
3
1
BUS CLOCK
X
To TBM
INTERNAL OSCILLATOR
MUX
R
2
1
OSCCLK
RC
From SIM
ICLK
I
R
1
1
To SIM
(and COP)
OSCCLK1
OSCCLK0
CONFIG2
Freescale Semiconductor
Bit 0
R
1