MC68HC908JK8CP Freescale Semiconductor, MC68HC908JK8CP Datasheet - Page 79

• Manufacturer Part Number: MC68HC908JK8CP
• Manufacturer: Freescale Semiconductor

Specifications of MC68HC908JK8CP

• Cpu Family: HC08
• Device Core Size: 8b
• Frequency (max): 8MHz
• Interface Type: SCI
• Program Memory Type: Flash
• Program Memory Size: 8KB
• Total Internal Ram Size: 256Byte
• # I/os (max): 15
• Number Of Timers - General Purpose: 4
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• On-chip Adc: 13-chx8-bit
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Through Hole
• Pin Count: 20
• Package Type: PDIP
• Lead Free Status / Rohs Status: Not Compliant

Chapter 6
Oscillator (OSC)
6.1 Introduction
The oscillator module provides the reference clocks for the MCU system and bus. Two oscillators are
running on the device:
Selectable oscillator — for bus clock
The selected oscillator is used to drive the bus clock, the SIM, and other modules on the MCU. The
oscillator type is selected by programming a bit FLASH memory. The RC and crystal oscillator cannot run
concurrently; one is disabled while the other is selected; because the RC and XTAL circuits share the
same OSC1 pin.
Non-selectable oscillator — for COP
This internal oscillator is used to drive the computer operating properly (COP) module and the SIM. The
internal oscillator runs continuously after a POR or reset, and is always available.
6.2 Oscillator Selection
The oscillator type is selected by programming a bit in a FLASH memory location; the mask option register
(MOR), at $FFD0.
(See
Freescale Semiconductor
•
•
•
3.5 Mask Option Register
Crystal oscillator (XTAL) — built-in oscillator that requires an external crystal or ceramic-resonator.
This option also allows an external clock that can be driven directly into OSC1.
RC oscillator (RC) — built-in oscillator that requires an external resistor-capacitor connection only.
Internal oscillator — built-in RC oscillator that requires no external components.
Non-volatile FLASH register; write by programming.
Address:
On the ROM device, the oscillator is selected by a ROM-mask layer at
factory.
Erased:
Reset:
Read:
Write:
MC68HC908JL8/JK8 • MC68HC08JL8/JK8 • MC68HC908KL8 Data Sheet, Rev. 3.1
OSCSEL
$FFD0
Bit 7
R
1
Figure 6-1. Mask Option Register (MOR)
= Reserved
(MOR).)
R
6
1
R
5
1
NOTE
Unaffected by reset
R
4
1
R
3
1
R
2
1
R
1
1
Bit 0
R
1
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