General Description
Technical Data MC68HC908AB32 — Rev. 1.0
32 General Description MOTOROLA
Figure 1-1. MC68HC908AB32 Block Diagram
CLOCK GENERATOR MODULE
SYSTEM INTEGRATION
MODULE
SERIAL PERIPHERAL
4-CHANNEL TIMER INTERFACE
MODULE B
LOW-VOLTAGE
INHIBIT MODULE
KEYBOARD
ARITHMETIC/LOGIC
UNIT (ALU)
CPU
REGISTERS
M68HC08 CPU
CONTROL AND STATUS REGISTERS — 80 BYTES
USER FLASH — 32,256 BYTES
USER RAM — 1024 BYTES
MONITOR ROM — 307 BYTES
USER FLASH VECTORS — 48 BYTES
SINGLE EXTERNAL IRQ
MODULE
PORTA
DDRA
DDRE
PORTE
INTERNAL BUS
OSC1
OSC2
CGMXFC
* RST
* IRQ
INTERFACE MODULE
INTERRUPT MODULE
COMPUTER OPERATING
PROPERLY MODULE
PTA7 – PTA0
V
REFH
PTE7/SPSCK
PTE6/MOSI
PTE5/MISO
PTE4/SS
PTE3/TACH1
PTE2/TACH0
PTE1/RxD
PTE0/TxD
A
VSS
/V
REFL
4-CHANNEL TIMER INTERFACE
MODULE A
4.9125-MHz OSCILLATOR
PHASE-LOCKED LOOP
SERIAL COMMUNICATIONS
INTERFACE MODULE
POWER-ON RESET
MODULE
POWER
V
SS
V
DD
V
SSA
V
DDA
†Ports are software configurable with pullup device if input port.
‡ Higher current drive port pins
* Pin contains integrated pullup device
** Pullup enabled when configured as keyboard interrupt pin
V
DDAREF
8-BIT ANALOG-TO-DIGITAL
CONVERTER MODULE
USER EEPROM — 512 BYTES
PROGRAMMABLE INTERRUPT
TIMER MODULE
PORTB
DDRB
PTB7/ATD7 – PTB0/ATD0
PORTC
DDRC
PTC5 – PTC0
PORTD
DDRD
PTD7 – PTD0
†‡
DDRF
PORTF
PTF7
â€
PTF6
â€
PTF5/TBCH1
â€
PTF4/TBCH0
â€
PTF3/TBCH3
â€
PTF2/TBCH2
â€
PTF1/TACH3
â€
PTF0/TACH2
â€
PORTG
DDRG
PTG2/KBD2 – PTG0/KBD0 **
PORTH
DDRH
PTH1/KBD4 – PTH0/KBD3 **
(PTC2/MCLK)
(PTD6/TACLK)
(PTD4/TBCLK)