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)