Introduction

The MC68HC908RF2 MCU is a member of the low-cost, high-performance M68HC08 Family of 8-bit microcontroller units (MCUs). Optimized for low-power operation and available in a small 32-pin low-profile quad flat pack (LQFP), this MCU is well suited for remote keyless entry (RKE) transmitter designs. The M68HC08 Family is based on the customer-specified integrated circuit (CSIC) design strategy. All MCUs in the family use the enhanced M68HC08 central processor unit (CPU08) and are available with a variety of modules, memory sizes and types, and package types.

Features

Features of the MC68HC908RF2 MCU include:

• High-performance M68HC08 architecture

• Fully upward-compatible object code with M6805, M146805, and M68HC05 Families

• Maximum internal bus frequency of 4 MHz at 3.3 volts

• Maximum internal bus frequency of 2 MHz at 1.8 volts

• Internal oscillator requiring no external components:

– Software selectable bus frequencies

– ± 25 percent accuracy with trim capability to ±2 percent

– Option to allow use of external clock source or external crystal/ceramic resonator

• 2 Kbytes of on-chip FLASH memory

• FLASH program memory security(1)

• 128 bytes of on-chip RAM

• 16-bit, 2-channel timer interface module (TIM)

• 12 general-purpose input/output (I/O) ports:

– Six shared with keyboard wakeup function

– Two shared with the timer module

– Port A pins have 3-mA sink capabilities

• Low-voltage inhibit (LVI) module:

– 1.85-V detection forces MCU into reset

– 2.0-V detection sets indicator flag

• 6-bit keyboard interrupt with wakeup feature

• External asynchronous interrupt pin with internal pullup (IRQ1)

• Ultra high frequency (UHF) transmitter

• System protection features:

– Computer operating properly (COP) reset

– Low-voltage detection with reset

– Illegal opcode detection with reset

– Illegal address detection with reset

• 32-pin plastic LQFP package

• Low-power design with stop and wait modes

• Master reset pin and power-on reset (POR)

• –40° to 85° Celsius operation

Features of the CPU08 include:

• Enhanced HC05 programming model

• Extensive loop control functions

• 16 addressing modes (eight more than the HC05)

• 16-bit index register and stack pointer

• Memory-to-memory data transfers

• Fast 8 × 8 multiply instruction

• Fast 16/8 divide instruction

• Binary-coded decimal (BCD) instructions

• Optimization for controller applications

• Third party C language support