Introduction
The Freescale MC68HC705MC4 microcontroller is a low-cost M68HC05 Family EPROM microcontroller intended for use in industrial motor control and power supply applications. Features include a 2-channel, 8-bit, high-speed pulse-width modulator (PWM) module (including a commutation multiplexer for brushless permanent magnet motor control), a 6-input, 8-bit analog-to-digital (A/D) controller to accommodate analog feedback signals, and a serial communications interface (SCI) to support multi-controller networking.

Features
Features of the MC68HC705MC4 are listed below. Note that all timing is based on a 3-MHz bus.
• Low-Cost, HC05 Core Running at 3-MHz Bus Speed at VDD = 5 V ± 10%
• 28-Pin Plastic Dual In-Line Package (PDIP), Small Outline Integrated Circuit (SOIC), or Windowed Ceramic Package with Low Electromagnetic Interference (EMI) Emission Pinout
• 3584 Bytes of User EPROM, Including Eight User Vectors of Two Bytes Each
• 176 Bytes of User RAM
• Dual-Channel, High-Speed PWM, Featuring:
    – 8-Bit Duty Cycle Resolution
    – Independent Prescaler Frequency Selection and Period Counters
    – Two Frequency Ranges, Eight Steps in Each: 183 Hz to 23.4 kHz 122 Hz to 15.6 kHz
    – Software Programmable PWM Polarity
    – Dual Software Controllable PWM Output Multiplexer, Each PWM to Three Input/Output (I/O)
• 8-Bit A/D Converter with Six Input Multiplexer
    – High and Low References
    – Conversion Rate = 10.7 µs
• 16-Bit Timer with Two Input Captures or One Input Capture Plus One Output Compare
    – Resolution = 1.33 µs
    – Input Capture Active Edge Software Selectable as Rising or Falling
• 15-Stage, Multi-Function Core Timer with Timer Overflow, Real-Time Interrupt, and Watchdog
• Asynchronous Serial Communications Interface (SCI)
• 22 General-Purpose I/O Lines, Some Shared with Peripheral Functions
• One 8-Bit High Source Current I/O Port
    – 10 mA/Pin
    – 20 mA Maximum/Port
    – Port A
• One High-Sink Current 10 mA Output Pin, PB7
• Mask, Request, Acknowledge, Edge and Sensitivity (Edge- and Level-Sensitive or Edge-Sensitive Only) Control/Status Bits for IRQ Interrupt
• On-Chip Oscillator for Crystal/Ceramic Resonator
• Mask Selectable Computer Operating Properly (COP) Watchdog System
• Illegal Address Reset
• Steering Diode on RESET Pin to VDD