Introduction
The MC68HC908GR16 is a member of the low-cost, high-performance M68HC08 Family of 8-bit microcontroller units (MCUs). 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
For convenience, features have been organized to reflect:
• Standard features of the MC68HC908GR16
• Features of the CPU08

Standard Features of the MC68HC908GR16
Features of the MC68HC908GR16 include:
• High-performance M68HC08 architecture optimized for C-compilers
• Fully upward-compatible object code with M6805, M146805, and M68HC05 Families
• 8-MHz internal bus frequency
• Clock generation module supporting 32-kHz to 100-kHz crystals
• FLASH program memory security(1)
• On-chip programming firmware for use with host personal computer which does not require high voltage for entry
• In-system programming (ISP)
• System protection features:
   – Optional computer operating properly (COP) reset
   – Low-voltage detection with optional reset and selectable trip points for 3.3-V and 5.0-V operation
   – Illegal opcode detection with reset
   – Illegal address detection with reset
• Low-power design; fully static with stop and wait modes
• Standard low-power modes of operation:
   – Wait mode
   – Stop mode
• Master reset pin and power-on reset (POR)
• 16 Kbytes of on-chip 100k cycle write/erase capable FLASH memory
• 1 Kbyte of on-chip random-access memory (RAM)
• 406 bytes of FLASH programming routines read-only memory (ROM)
• Serial peripheral interface (SPI) module
• Enhanced serial communications interface (ESCI) module
• Two 16-bit timer interface modules (2-channel TIM1 and 2-channel TIM2) with selectable input capture, output compare, and pulse-width modulation (PWM) capability on each channel
• 8-channel, 10-bit successive approximation analog-to-digital converter (ADC)
• BREAK (BRK) module to allow single breakpoint setting during in-circuit debugging
• Internal pullups on IRQ and RST to reduce customer system cost
• Up to 37 general-purpose input/output (I/O) pins, including:
   – 28 shared-function I/O pins
   – Up to nine dedicated I/O pins, depending on package choice
• Selectable pullups on inputs only on ports A, C, and D. Selection is on an individual port bit basis. During output mode, pullups are disengaged.
• High current 10-mA sink/source capability on all port pins
• Higher current 20-mA sink/source capability on PTC0–PTC4
• Timebase module (TBM) with clock prescaler circuitry for eight user selectable periodic real-time interrupts with optional active clock source during stop mode for periodic wakeup from stop using an external crystal
• User selection of having the oscillator enabled or disabled during stop mode
• 8-bit keyboard wakeup port
• 5 mA maximum current injection on all port pins to maintain input protection
• Available packages:
   – 32-pin LQFP
   – 48-pin low-profile quad flag pack (LQFP)
• Specific features of the MC68HC908GR16 in 32-pin LQFP are:
   – Port A is only 4 bits: PTA0–PTA3; 4-pin keyboard interrupt (KBI) module
   – Port B is only 6 bits: PTB0–PTB5; 6-channel ADC module
   – Port C is only 2 bits: PTC0–PTC1
   – Port D is only 7 bits: PTD0–PTD6; shared with SPI, TIM1, and TIM2 modules
   – Port E is only 2 bits: PTE0–PTE1; shared with ESCI module
• Specific features of the MC68HC908GR16 in 48-pin LQFP are:
   – Port A is 8 bits: PTA0–PTA7; 8-pin KBI module
   – Port B is 8 bits: PTB0–PTB7; 8-channel ADC module
   – Port C is only 7 bits: PTC0–PTC6
   – Port D is 8 bits: PTD0–PTD7; shared with SPI, TIM1, and TIM2 modules
   – Port E is only 6 bits: PTE0–PTE5; shared with ESCI module

Features of the CPU08
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
• Efficient C language support