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)

• Two enhanced asynchronous non-return-to-zero (NRZ) serial communication interfaces (SCI)

• Enhanced synchronous serial peripheral interface (SPI)

• 8-channel, 8-bit analog-to-digital converter (ATD)

• Up to 24 key wakeup lines with interrupt capability

• Available in 112-lead low-profile quad flat pack (LQFP) packaging