General Description
1.1 Introduction
The MC68HC908GT16, MC68HC908GT8, and MC68HC08GT16 are members 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.
All references to the MC68HC908GT16 in this data book apply equally to the MC68HC908GT8, unless otherwise stated.
This revision introduces the MC68HC08GT16, the ROM part equivalent to the MC68HC908GT16. The entire data book applies to this ROM device, with the exceptions outlined in Appendix A MC68HC08GT16.
1.2 Features
For convenience, features have been organized to reflect:
• Standard features of the MC68HC908GT16/MC68HC908GT8
• Features of the CPU08
1.2.1 Standard Features of the MC68HC908GT16/MC68HC908GT8
• High-performance M68HC08 architecture optimized for C-compilers
• Fully upward-compatible object code with M6805, M146805, and M68HC05 Families
• 8-MHz internal bus frequency
• Internal oscillator requiring no external components:
– Software selectable bus frequencies
– ±25 percent accuracy with trim capability to ±4 percent
– Clock monitor
– Option to allow use of external clock source or external crystal/ceramic resonator
• 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 3.0-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 (8 Kbytes on MC68HC908GT8)
• 512 bytes of on-chip random-access memory (RAM)
• 720 bytes of Flash programming routines ROM
• Serial peripheral interface module (SPI)
• Serial communications interface module (SCI)
• Two 16-bit, 2-channel timer interface modules (TIM1 and TIM2) with selectable input capture, output compare, and pulse-width modulation (PWM) capability on each channel
• 8-channel, 8-bit successive approximation analog-to-digital converter (ADC)
• Break module (BRK) to allow single breakpoint setting during in-circuit debugging
• Internal pullups on IRQ and RST to reduce customer system cost
• Up to 36 general-purpose input/output (I/O) pins, including:
– 28 shared-function I/O pins
– Six or eight 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/10-mA source capability on all port pins
• Higher current 20-mA sink/source capability on PTC0–PTC4
• Timebase module 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 32-kHz crystal or internal oscillator
• User selection of having the oscillator enabled or disabled during stop mode
• 8-bit keyboard wakeup port
• Available packages:
– 42-pin shrink dual in-line package (SDIP)
– 44-pin quad flat pack (QFP)
• Specific features of the MC68HC908GT16 in 42-pin SDIP are:
– Port C is only 5 bits: PTC0–PTC4
– Port D is 8 bits: PTD0–PTD7; dual 2-channel TIM modules
• Specific features of the MC68HC908GT16 in 44-pin QFP are:
– Port C is 7 bits: PTC0–PTC6
– Port D is 8 bits: PTD0–PTD7; dual 2-channel TIM modules
1.2.2 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
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MC68HC08GT16.pdf
