NXP Semiconductors MC908QY4ACDWE

Overview

MC908QY4ACDWE from Freescale Semiconductor is an 8-bit HCS08-core microcontroller with 4 KB Flash, 192 B RAM, 10-bit ADC, on-chip oscillator, COP watchdog, and AWU wake-up module. It operates at up to 8 MHz bus frequency, supports 2.7–5.5 V supply, and targets low-power embedded control in industrial sensors and appliance subsystems.

For engineers reviewing the MC908QY4ACDWE datasheet, MC908QY4ACDWE pinout, MC908QY4ACDWE application, or MC908QY4ACDWE equivalent, key selection criteria include Flash security byte validation ($FFF6–$FFFD), internal oscillator trim register support (ICSTRM), AWU-driven low-power operation, and compatibility with HC08 development tools including P&E Multilink and Cyclone Pro.

Technical Context

The MC908QY4ACDWE implements the HCS08 CPU core with 16-bit address space, supporting indexed, extended, and relative addressing modes. Its memory map includes 4 KB of on-chip SuperFlash® (programmable in-system), 192 B RAM, and dedicated registers for ADC10, AWU, KBI, LVI, and SIM modules.

Security enforcement occurs during monitor mode entry: host must supply eight matching bytes to $FFF6–$FFFD, and entry is denied if ≥5 of those bytes are $00. The internal oscillator supports trimming via ICSTRM register (address $003F) for ±2% accuracy across voltage/temperature.

Key Specifications

Pinout & Package

MC908QY4ACDWE is housed in a 20-pin SOIC (Small Outline Integrated Circuit) package with 0.300-inch body width and standard JEDEC MS-013 footprint. Pin functions are defined per Chapter 1.4 (Pin Assignments) and Chapter 1.5 (Pin Functions) of the MC68HC908QY4A Rev. 3 datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908QY2ACDWE and MC908QY4CDWE, the MC908QY4ACDWE provides full industrial temperature support and maximum on-chip memory - critical for field-deployed equipment requiring long-term reliability and firmware update headroom.

Availability

MC908QY4ACDWE is available at Aetrix Electronics and suitable for industrial sensor nodes, home appliance control panels, smart meter subsystems, and legacy equipment retrofit programs requiring stable component supply and long-lifecycle support.

Supply support for MC908QY4ACDWE 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) designed high-reliability, cost-optimized 8-bit microcontrollers for industrial and consumer embedded systems.

The MC68HC908QY4A belongs to the HCS08-based QY/QTA family - engineered for low-power, pin-efficient control in space-constrained applications with integrated analog and timing peripherals.

FAQ

What is the maximum bus frequency supported by the MC908QY4ACDWE?

The MC908QY4ACDWE supports a maximum bus frequency of 8 MHz. This is achieved using either the internal RC oscillator (calibrated via ICSTRM register) or an external crystal up to 8 MHz connected to XTAL/EXTAL pins. The bus clock drives all peripheral modules including ADC, TIM, and KBI, and directly determines instruction execution speed and conversion timing accuracy.

How does the Flash security feature work on the MC908QY4ACDWE?

The MC908QY4ACDWE enforces Flash security during monitor mode entry: the host debugger must transmit eight bytes matching those stored at memory addresses $FFF6–$FFFD. If five or more of those bytes are $00, monitor mode entry is denied. This prevents unauthorized firmware readout and protects intellectual property in deployed devices.

Which pins on the MC908QY4ACDWE support keyboard interrupt functionality?

The MC908QY4ACDWE supports keyboard interrupt (KBI) on Port A pins PA0 through PA7. These pins can be individually enabled as edge-sensitive wake sources via the Keyboard Interrupt Enable Register (KBIER). When configured, any transition on an enabled KBI pin generates an interrupt and can wake the MCU from wait or stop mode - ideal for low-power keypad interfaces.

Does the MC908QY4ACDWE include a hardware watchdog timer?

Yes, the MC908QY4ACDWE includes a Computer Operating Properly (COP) watchdog module. It uses a programmable timeout (from 1.0 ms to 1.3 s) based on internal RC oscillator cycles. If the COP counter is not cleared by software before timeout, it triggers a hardware reset - ensuring recovery from runaway code or lockup conditions in safety-critical applications.

What is the purpose of the ICSTRM register in the MC908QY4ACDWE?

The ICSTRM register (located at address $003F) stores the internal oscillator trim value for the MC908QY4ACDWE. Writing to this register adjusts the RC oscillator frequency to achieve ±2% accuracy across voltage and temperature variations. This eliminates the need for external timing components in cost-sensitive designs while maintaining reliable bus clock stability for ADC sampling and communication timing.