MC68HC908RK2 Datasheet, PDF (15/158 Pages) Motorola, Inc – Microcontroller Unit

Chapter 1
General Description
1.1 Introduction
The MC68HC908RK2 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 20-pin
SSOP/SOIC package, this MCU is well suited for remote keyless entry (RKE) transmitter designs.
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.
1.2 Features
Features 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)
• 14 general-purpose input/output (I/O) ports:
– Six shared with keyboard wakeup function
– Three shared with the timer module
– Port A pins have 3-mA sink capabilities
• Low-voltage inhibit 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 (IRQ)
1. No security feature is absolutely secure. However, Freescale’s strategy is to make reading or copying the FLASH difficult for
unauthorized users.
MC68HC908RK2 Data Sheet, Rev. 5.1
Freescale Semiconductor
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