mc9s12xf512 Freescale Semiconductor, Inc, mc9s12xf512 Datasheet - Page 81

• Manufacturer Part Number: mc9s12xf512
• Description: S12x Microcontrollers 16-bit Automotive Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

1.13
The XCLKS is an input signal which controls whether a crystal in combination with the internal loop
controlled (low power) Pierce oscillator is used or whether full swing Pierce oscillator/external clock
circuitry is used. For this device XCLKS is mapped to PE7.
The XCLKS signal selects the oscillator configuration during reset low phase while a clock quality check
is ongoing. This is the case for:
The selected oscillator configuration is frozen with the rising edge of the RESET pin in any of these above
described reset cases.
Freescale Semiconductor
•
•
•
Power on reset or low-voltage reset
Clock monitor reset
Any reset while in self-clock mode or full stop mode
Oscillator Configuration
Figure 1-9. Loop Controlled Pierce Oscillator Connections (XCLKS = 1)
Figure 1-10. Full Swing Pierce Oscillator Connections (XCLKS = 0)
MCU
Figure 1-11. External Clock Connections (XCLKS = 0)
EXTAL
XTAL
MC9S12XF - Family Reference Manual, Rev.1.19
MCU
MCU
EXTAL
EXTAL
XTAL
R
XTAL
B
=1MΩ ; R
R
S
R
B
S
Not Connected
specified by crystal vendor
Ceramic Resonator
Crystal or
CMOS-Compatible
External Oscillator
C
C
Ceramic Resonator
1
2
Crystal or
C
C
1
2
V
Chapter 1 MC9S12XF-Family Reference Manual
SSPLL
V
SSPLL
81