General Description

1.1 Introduction

The MC68HC05P4A is a 28-pin MCU (microcontroller unit) based on the MC68HC05P4. The memory map includes 4160 bytes of user ROM and 176 bytes of RAM. The MCU has two 8-bit input/output (I/O) ports, A and C. Port B has three I/O pins and port D has two pins, one that is I/O and the other input only. The MC68HC05P4A includes a simple serial I/O peripheral (SIOP) and an on-chip mask programmable computer operating properly (COP) watchdog circuit.

1.2 Features

Features of the MC68HC05P4A include:

• Low cost

• HC05 core

• 28-pin package

• On-chip oscillator with RC (resistor capacitor) or crystal/ceramic resonator mask options

• 4160 bytes of user read-only memory (ROM), including 16 user vector locations

• ROM security feature(1)

• 176 bytes of on-chip random-access memory (RAM)

• 16-bit timer

• 20 bidirectional input/output (I/O) lines, one input-only line

• Mask programmable keyscan (pullups and interrupt) on eight port pins (PA0–PA7)

• Two port pins with high current drive capability

• User mode

• Self-check mode

• Power-saving stop and wait modes

• Edge-sensitive or edge- and level-sensitive interrupt trigger mask option

• Simple serial I/O port

• Mask option selectable computer operating properly (COP) watchdog timer

1.3 Mask Options

The MC68HC05P4A has 13 mask options:

• CLOCK, RC or crystal

• IRQ, edge-sensitive only or edge- and level-sensitive

• SIOP, most significant bit (MSB) or least significant bit (LSB) first

• COP watchdog timer, enable/disable

• Keyscan pullups and interrupts on port A, enable/disable by pin

• STOP instruction