MC908AP8CFBE Datasheet, PDF (73/324 Pages) Freescale Semiconductor, Inc – Microcontrollers

OSCSEL1
0
0
1
1
OSCSEL0
0
1
0
1
Clock Selection
Table 5-1. CGMXCLK Clock Selection
CGMXCLK
—
ICLK
RCCLK
XCLK
OSC2 Pin
—
f_BUS
f_BUS
Inverting
output of
X-TAL
Comments
Not used
Internal oscillator generates the CGMXCLK.
RC oscillator generates the CGMXCLK.
Internal oscillator is available after each POR or
reset.
X-tal oscillator generates the CGMXCLK.
Internal oscillator is available after each POR or
reset.
NOTE
The internal oscillator is a free running oscillator and is available after each
POR or reset. It is turned-off in stop mode by setting the STOP_ICLKDIS
bit in CONFIG2.
5.2.2 TBM Reference Clock Selection
The timebase module reference clock (OSCCLK) is selected by configuring two bits in the CONFIG2
register, at $001D. See Chapter 3 Configuration & Mask Option Registers (CONFIG & MOR).
Address: $001D
Bit 7
6
5
4
3
2
1
Read: _{STOP_}
Write: ^ICLKDIS
STOP_
RCLKEN
STOP_
XCLKEN
OSCCLK1 OSCCLK0
0
0
Reset: 0
0
0
0
0
0
0
Figure 5-3. Configuration Register 2 (CONFIG2)
Bit 0
SCIBD-
SRC
0
Table 5-2. Timebase Module Reference Clock Selection
OSCCLK1
0
0
1
1
OSCCLK0
0
1
0
1
Timebase Clock Source
Internal oscillator (ICLK)
RC oscillator (RCCLK)
X-tal oscillator (XCLK)
Not used
NOTE
The RCCLK or XCLK is only available if that clock is selected as the CGM
reference clock, whereas the ICLK is always available.
MC68HC908AP Family Data Sheet, Rev. 4
Freescale Semiconductor
73