General Description
Introduction
The MC68HC812A4 microcontroller unit (MCU) is a 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include:
  • 16-bit central processor unit (CPU12)
  • Lite integration module (LIM)
  • Two asynchronous serial communications interfaces (SCI0 and SCI1)
  • Serial peripheral interface (SPI)
  • Timer and pulse accumulator module
  • 8-bit analog-to-digital converter (ATD)
  • 1-Kbyte random-access memory (RAM)
  • 4-Kbyte electrically erasable, programmable read-only memory (EEPROM)
  • Memory expansion logic with chip selects, key wakeup ports, and a phase-locked loop (PLL)

Features
Features of the MC68HC812A4 include:
  • Low-power, high-speed M68HC12 CPU
  • Power-saving stop and wait modes
  • Memory:
     – 1024-byte RAM
     – 4096-byte EEPROM
     – On-chip memory mapping allows expansion to more than 5-Mbyte address space
  • Single-wire background debug mode
  • Non-multiplexed address and data buses
  • Seven programmable chip-selects with clock stretching (expanded modes)
  • 8-channel, enhanced 16-bit timer with programmable prescaler:
     – All channels configurable as input capture or output compare
     – Flexible choice of clock source
  • 16-bit pulse accumulator
  • Real-time interrupt circuit
  • Computer operating properly (COP) watchdog
  • Clock monitor
  • Phase-locked loop (PLL)