MC68HC908LB8_05 Datasheet, PDF (124/234 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Oscillator Module (OSC)
M68HC08 CPU
CPU
REGISTERS
ARITHMETIC/LOGIC
UNIT (ALU)
CONTROL AND STATUS
REGISTERS — 64 BYTES
USER FLASH — 8 KBYTES
USER RAM — 128 BYTES
INTERNAL BUS
DUAL CHANNEL PWM
MODULE
HIGH RESOLUTION PWM
MODULE
LOW-VOLTAGE INHIBIT
MODULE
PTA6⁽¹⁾/AD5/TCH0/KBI6
PTA5⁽¹⁾/RST/KBI5
PTA4⁽¹⁾/AD4/KBI4
PTA3⁽¹⁾/AD3/KBI3
PTA2⁽¹⁾/AD2/KBI2
PTA1⁽¹⁾/AD1/KBI1
PTA0⁽¹⁾/AD0/KBI0
MONITOR ROM — 350 BYTES
FLASH PROGRAMMING
ROUTINES ROM — 674 BYTES
USER FLASH VECTOR SPACE — 34 BYTES
OSCILLATOR
MODULE
COMPUTER OPERATING
PROPERLY MODULE
2-CHANNEL TIMER
MODULE
8-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
PTB7/V_OUT/AD6/FAULT⁽²⁾
PTB6/V–
PTB5/V+
PTB4/PWM1
PTB3/PWM0
PTB2/FAULT⁽²⁾
PTB1/BOT
PTB0/TOP
SYSTEM INTEGRATION
MODULE
KEYBOARD INTERRUPT
MODULE
PTC2⁽¹⁾/SHTDWN/IRQ
PTC1⁽¹⁾/OSC2
PTC0⁽¹⁾/OSC1
V_DD
POWER
V_SS
OP AMP/COMPARATOR
MODULE
Notes:
1. Pin contains integrated pullup device.
2. Fault function switchable between pins PTB2 and PTB7.
Figure 13-1. Block Diagram Highlighting OSC Block and Pins
13.3.1 Internal Oscillator
The internal oscillator circuit is designed for use with no external components to provide a clock source
with tolerance less than ±25% untrimmed. An 8-bit trimming register allows the adjust to a tolerance of
less than ±5%.
The internal oscillator will generate a clock of 16 MHz typical (INTCLK) resulting in a bus speed (internal
clock ÷ 4) of 4 MHz.
Figure 13-3 shows how BUSCLKX4 is derived from INTCLK and, like the RC oscillator, OSC2 can output
BUSCLKX4 by setting OSC2EN in PTCPUE register. See Chapter 14 Input/Output (I/O) Ports.
MC68HC908LB8 Data Sheet, Rev. 1
124
Freescale Semiconductor