NXP Semiconductors MC68HC908GR8CDW

Overview

MC68HC908GR8CDW from Freescale Semiconductor (formerly Motorola) is an 8-bit HCS08 microcontroller featuring 8 KB on-chip flash memory, 512 bytes RAM, and integrated peripherals including ADC, SCI, SPI, TIM, and KBI. It operates at up to 8 MHz bus frequency with 5 V or 3 V supply, and targets cost-sensitive embedded control in industrial sensors and appliance motor interfaces.

For engineers reviewing the MC68HC908GR8CDW datasheet, MC68HC908GR8CDW pinout, MC68HC908GR8CDW application, or MC68HC908GR8CDW equivalent, key selection criteria include its 28-pin SOIC package, 8-channel 8-bit ADC, COP watchdog, low-power stop/wait modes, and compatibility with HC08 development tools and MON monitor ROM for in-circuit debugging.

Technical Context

The MC68HC908GR8CDW implements the HCS08 CPU core with enhanced addressing modes and a 16-bit index register. Its System Integration Module (SIM) manages clock generation, reset sequencing, interrupt vectoring, and low-power mode transitions across multiple peripheral modules.

Peripheral integration includes a 16-bit Timer Interface Module (TIM) with input capture/output compare, a Serial Communications Interface (SCI) supporting asynchronous full-duplex UART operation, and a Serial Peripheral Interface (SPI) with master/slave capability - all synchronized to the internal bus clock and configurable via dedicated I/O registers.

Key Specifications

Pinout & Package

MC68HC908GR8CDW is housed in a 28-pin Small Outline Integrated Circuit (SOIC) package (Case #751F), with 24 I/O pins distributed across Ports A–E, plus power, ground, reset, and oscillator connections.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microcontroller applications.

Compared with MC68HC908GR4CDW, the MC68HC908GR8CDW provides double flash and RAM for enhanced firmware capability without layout changes; versus MC9RS08KA2CSC, it delivers richer peripheral integration and larger memory at the cost of higher pin count and power consumption.

Availability

MC68HC908GR8CDW is available at Aetrix Electronics and suitable for industrial sensor nodes, home appliance motor controllers, POS keypad interfaces, and legacy panel controller upgrades requiring stable component supply and long-term manufacturability.

Supply support for MC68HC908GR8CDW includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Freescale Semiconductor (now part of NXP Semiconductors) was a leading designer of embedded processors and analog/mixed-signal ICs, known for automotive, industrial, and consumer microcontrollers.

The MC68HC908GR8CDW belongs to the HCS08 family - a cost-optimized 8-bit MCU line targeting resource-constrained industrial and appliance applications with integrated analog peripherals and robust debug support.

FAQ

What is the maximum operating frequency of the MC68HC908GR8CDW?

The MC68HC908GR8CDW supports a maximum bus frequency of 8 MHz, achieved using an external crystal or ceramic resonator connected to the XTAL/EXTAL pins. This frequency defines the timing base for all internal peripherals including the ADC, SCI, and TIM modules, and directly impacts instruction execution speed and real-time response capability in the MC68HC908GR8CDW.

Does the MC68HC908GR8CDW include a hardware watchdog timer?

Yes, the MC68HC908GR8CDW integrates a Computer Operating Properly (COP) module - a configurable watchdog timer with selectable timeout periods ranging from 1.8 ms to 2.3 s. The COP must be periodically cleared by firmware; failure to do so triggers a system reset, ensuring recovery from software hangs or infinite loops in the MC68HC908GR8CDW.

Can the MC68HC908GR8CDW perform in-system programming without external hardware?

Yes, the MC68HC908GR8CDW contains a built-in Monitor ROM (MON) that enables in-system programming and debugging via its SCI interface. Using standard UART signals, developers can erase, program, and verify flash memory on the target board without requiring a dedicated programmer - a key capability supported natively by the MC68HC908GR8CDW.

What ADC resolution and channel count does the MC68HC908GR8CDW provide?

The MC68HC908GR8CDW features an 8-bit successive-approximation analog-to-digital converter with 8 input channels (AN0–AN7), mapped across Port A and Port E pins. Conversion time is programmable via ADC clock division, and results are stored in dedicated result registers accessible by firmware - a core analog interface function of the MC68HC908GR8CDW.

Is the MC68HC908GR8CDW pin-compatible with other members of the GR-series?

Yes, the MC68HC908GR8CDW shares identical pinout and peripheral register mapping with the MC68HC908GR4CDW in the same 28-pin SOIC package. This allows direct substitution where increased flash (8 KB vs. 4 KB) and RAM (512 B vs. 256 B) are required, maintaining full hardware compatibility across both variants of the MC68HC908GR8CDW and MC68HC908GR4CDW.