GENERAL DESCRIPTION
The MC68HC05P9A is a 28-pin device based on the MC68HC05P9. The memory
map includes 2112 bytes of user ROM and 128 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 MC68HC05P9A includes a
four-channel 8-bit analog-to-digital (A/D) converter, a simple serial I/O peripheral
(SIOP), and an on-chip mask programmable computer operating properly (COP)
watchdog circuit.

Features
• Low Cost
• HC05 Core
• 28-Pin Package
• On-Chip Oscillator with RC or Crystal/Ceramic Resonator Mask Options
• 2112 Bytes of User ROM Including 16 User Vector Locations
• ROM Security Feature
• 128 Bytes of On-Chip RAM
• 16-Bit Timer
• 20 Bidirectional I/O Lines, One Input-Only Line
• Mask Programmable Keyscan (Pullups and Interrupt) on Eight Port Pins
(PA0 through PA7)
• Two Port Pins with High Current Drive Capability (PC0, PC1)
• User Mode
• Four-Channel 8-Bit A/D Converter
• Self-Check Mode
• Power-Saving Stop and Wait Modes
• STOP Conversion to Halt Mode (Mask Option)
• Edge-Sensitive or Edge- and Level-Sensitive Interrupt Trigger Mask
Option
• Simple Serial Input/Output Port
• Mask Option Selectable Watchdog Timer (COP)