NXP Semiconductors MC68HC908GR4CFAE

Overview

MC68HC908GR4CFAE from Freescale Semiconductor is an 8-bit HCS08 microcontroller with 4 KB on-chip flash memory, 192 B RAM, and integrated peripherals including 8-channel 8-bit ADC, SCI, SPI, TIM, and KBI modules. It operates at up to 8 MHz bus frequency, supports 3.0–5.5 V supply, and targets embedded control in industrial sensors and appliance subsystems.

For engineers reviewing the MC68HC908GR4CFAE datasheet, MC68HC908GR4CFAE pinout, MC68HC908GR4CFAE application, or MC68HC908GR4CFAE equivalent, key selection criteria include its 28-pin SOIC package, 8-bit CPU core with COP watchdog, low-power stop/wait modes, and compatibility with HC08 development tools and MON ROM-based programming.

Technical Context

The MC68HC908GR4CFAE implements the M68HC08 CPU core with 16-bit address space, supporting indexed, extended, and relative addressing. Its System Integration Module (SIM) integrates clock generation, reset control, interrupt vectoring, and low-power mode management.

Peripheral integration includes a 16-bit Timer Interface Module (TIM) with input capture/output compare, a Serial Communications Interface (SCI) supporting asynchronous full-duplex communication, and a Serial Peripheral Interface (SPI) for synchronous master/slave data exchange - all directly memory-mapped and interrupt-capable.

Key Specifications

Pinout & Package

MC68HC908GR4CFAE is housed in a 28-pin Small Outline Integrated Circuit (SOIC) package (Case #751F), 300 mil body width, with 1.27 mm pitch and surface-mount footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit microcontroller applications.

Compared with MC9RS08KA2CFAE and STM8S003F3P6, the MC68HC908GR4CFAE provides proven MON ROM-based field programming, deterministic 8 MHz timing for legacy timing-critical designs, and direct compatibility with existing HC08 development infrastructure - making it optimal for maintenance and long-lifecycle industrial deployments.

Availability

MC68HC908GR4CFAE is available at Aetrix Electronics and suitable for industrial sensor nodes, home appliance control units, motor drive subsystems, and smart power outlets requiring stable component supply and long-term obsolescence management.

Supply support for MC68HC908GR4CFAE 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 controllers, analog, and RF solutions for automotive, industrial, and consumer markets.

The MC68HC908GR4CFAE belongs to the HCS08 family - engineered for cost-sensitive, low-power 8-bit control applications where flash programmability, peripheral integration, and toolchain maturity are critical.

FAQ

What is the maximum operating frequency of the MC68HC908GR4CFAE?

The MC68HC908GR4CFAE supports a maximum bus frequency of 8 MHz when powered at 5.0 V, and 4 MHz at 3.0 V. This frequency determines instruction execution speed, ADC conversion rate, and peripheral timing resolution. The actual achievable frequency depends on external crystal or oscillator stability and PCB layout - design validation requires measurement under worst-case voltage and temperature conditions.

Does the MC68HC908GR4CFAE include a hardware watchdog timer?

Yes, the MC68HC908GR4CFAE includes a Computer Operating Properly (COP) module that functions as a configurable watchdog timer. It offers timeout periods ranging from 0.5 ms to 1.0 s and must be refreshed by software within each interval; failure triggers a hardware reset. The COP is enabled/disabled via the CONFIG register and remains active in Wait mode but is disabled in Stop mode.

Can the MC68HC908GR4CFAE be programmed in-circuit without an external programmer?

Yes, the MC68HC908GR4CFAE contains a 1 KB Monitor ROM (MON) that enables in-circuit programming and debugging via its SCI interface. Using standard UART commands (e.g., READ, WRITE, RUN), firmware can be loaded, verified, and executed without removing the device from the board - a key advantage for field updates and production programming.

What analog input capability does the MC68HC908GR4CFAE provide?

The MC68HC908GR4CFAE integrates an 8-channel, 8-bit successive-approximation ADC with programmable sample time and multiple trigger sources (software, TIM, SCI). Input range is 0–VDD, and conversion time is 25 µs typical at 8 MHz bus clock. Channels map to Port A pins (PA0–PA7), supporting single-ended acquisition only - differential mode is not implemented.

Is the MC68HC908GR4CFAE pin-compatible with the MC68HC908GR8CFAE?

No, the MC68HC908GR4CFAE is not pin-compatible with the MC68HC908GR8CFAE. Although both use the same 28-pin SOIC package and share identical pin functions for core signals (VDD, VSS, XTAL, RESET, etc.), the GR8 variant allocates additional Port D pins (PD0–PD3) that are unimplemented on the GR4. Pin assignments for Port A and peripheral functions differ in allocation and multiplexing - PCB layout must be verified against each device's specific pin diagram.