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Introduction

The MC68HC705J1A is a member of Motorola¡¯s low-cost, high-performance M68HC05 Family of 8-bit microcontroller units (MCUs). The M68HC05 Family is based on the customer-specified integrated circuit (CSIC) design strategy. All MCUs in the family use the popular M68HC05 central processor unit (CPU) and are available with a variety of subsystems, memory sizes and types, and package types.

On-chip memory of the MC68HC705J1A includes 1240 bytes of erasable, programmable read-only memory (EPROM). In packages without the transparent window for EPROM erasure, the 1240 EPROM bytes serve as one-time programmable read-only memory (OTPROM).

Features

Features of the MC68HC705J1A include:

? Peripheral modules:

¨C 15-stage multifunction timer

¨C Computer operating properly (COP) watchdog

? 14 bidirectional input/output (I/O) lines, including:

¨C 10-mA sink capability on four I/O pins

¨C Mask option register (MOR) and software programmable pulldowns on all I/O pins

¨C MOR selectable interrupt on four I/O pins, a keyboard scan feature

? MOR selectable sensitivity on external interrupt (edge- and level-sensitive or edge-sensitive only)

? On-chip oscillator with connections for:

¨C Crystal

¨C Ceramic resonator

¨C Resistor-capacitor (RC) oscillator

¨C External clock

? 1240 bytes of EPROM/OTPROM, including eight bytes for user vectors

? 64 bytes of user random-access memory (RAM)

? Memory-mapped I/O registers

? Fully static operation with no minimum clock speed

? Power-saving stop, halt, wait, and data-retention modes

? External interrupt mask bit and acknowledge bit

? Illegal address reset

? Internal steering diode and pullup resistor from RESET pin to VDD