Introduction
The FreescaleMC68HC05P1A microcontroller unit (MCU) is pin compatible with the MC68HC05P1 with port and interrupt enhancements available. This device is available in a 28-pin dual in-line
package (DIP) or a small outline integrated circuit (SOIC) package. A functional block diagram of the MC68HC05P1A is shown inFigure 1-1.

FEATUREs
Features of the MC68HC05P1A include:
• Low-Cost, M68HC05 Core
• 28-Pin Dual In-Line Package (DIP) or Small Outline Integrated Circuit (SOIC) Package
• On-Chip Crystal/Ceramic Resonator or RC Oscillator (Mask Option)
• 2320 Bytes of User Read-Only Memory (ROM) Including:
– 48 Bytes of Page-Zero ROM
– 16 Bytes of User Vectors
• 128 Bytes of On-Chip Random Access Memory (RAM)
• 16-Bit Timer with Output Compare and Input Capture
• Edge/Level-Sensitive Interrupt or Edge-Sensitive Only (Mask Option)
• Computer Operating Properly (COP) Watchdog Timer
• 20 Bidirectional Input/Output (I/O) Lines and One Input-Only Line Including:
– Individual Mask Selectable Pullups/Interrupts on Port A Pins
– High Current Sink and Source on Two I/O Pins (PC0 and PC1)
• Single-Chip Mode
• Power-Saving Stop and Wait Modes
• Stop Conversion to Halt Mode (Mask Option)