mc9s12xd256 Freescale Semiconductor, Inc, mc9s12xd256 Datasheet - Page 68

• Manufacturer Part Number: mc9s12xd256
• Description: Hcs12x Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 1 Device Overview MC9S12XD-Family
1.3
The clock and reset generator module (CRG) provides the internal clock signals for the core and all
peripheral modules.
See 79Chapterf or details on clock generation.
The MCU’s system clock can be supplied in several ways enabling a range of system operating frequencies
to be supported:
The clock generated by the PLL or oscillator provides the main system clock frequencies core clock and
bus clock. As shown in
memories, and the peripherals.
The program Flash memory and the EEPROM are supplied by the bus clock and the oscillator clock.The
oscillator clock is used as a time base to derive the program and erase times for the NVM’s. See the Flash
and EEPROM section for more details on the operation of the NVM’s.
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EXTAL
XTAL
The on-chip phase locked loop (PLL)
the PLL self clocking
the oscillator
SCI Modules
System Clock Description
Bus Clock
RAM
CRG
Figure 1-12
Figure
Figure 1-14. MC9S12XD Family Clock Connections
SPI Modules
1-12, this system clocks are used throughout the MCU to drive the core, the
S12X
shows the clock connections from the CRG to all modules.
MC9S12XDP512 Data Sheet, Rev. 2.17
Core Clock
CAN Modules
XGATE
Oscillator Clock
FLASH
IIC Modules
EEPROM
Freescale Semiconductor
ATD Modules
ECT
PIM
PIT