NXP Semiconductors MC908MR8CPE

Overview

MC908MR8CPE from Freescale Semiconductor is an 8-bit HCS08 microcontroller with 8 KB on-chip FLASH, 512 B RAM, integrated 10-bit ADC (8 channels), dual 16-bit timers (TIMA/TIMB), SCI serial interface, and a dedicated 6-channel PWM motor control module (PWMMC) supporting complementary outputs with dead-time insertion and fault protection. It operates at up to 8 MHz bus frequency and targets embedded motor control in industrial actuators and small appliances.

For engineers reviewing the MC908MR8CPE datasheet, MC908MR8CPE pinout, MC908MR8CPE application, or MC908MR8CPE equivalent, key selection criteria include its integrated PWMMC with hardware fault shutdown, 10-bit ADC resolution for analog sensing, SCI for host communication, COP watchdog, and support for low-power Wait/Stop modes in battery-constrained systems.

Technical Context

The MC908MR8CPE implements the HCS08 CPU core with enhanced addressing modes and a 16-level hardware stack. Its System Integration Module (SIM) manages clock generation, reset sources (POR, LVI, COP, IRQ), and low-power modes. The Clock Generator Module (CGM) includes a crystal oscillator and PLL for flexible bus clock derivation.

The Pulse-Width Modulator for Motor Control (PWMMC) provides six independent or three complementary PWM outputs with programmable dead time, automatic fault response via PTC0–PTC1 fault pins, and synchronous initialization. TIMA and TIMB each support input capture, output compare, and buffered/unbuffered PWM - enabling precise timing for sensor feedback and commutation logic.

Key Specifications

Pinout & Package

MC908MR8CPE is housed in a 48-pin QFP (Quad Flat Package) with 0.5 mm pitch, compliant with JEDEC MO-148. Pin functions are validated per Freescale MC68HC908MR8 Rev 4.1 datasheet Section 1.5 (Pin Assignments).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC908MR16CPE and S9KEAZ128AMLH, the MC908MR8CPE offers optimal cost-performance balance for established 8-bit motor control applications with constrained memory needs and legacy codebases, while retaining full peripheral functionality for BLDC, stepper, and universal motor drives.

Availability

MC908MR8CPE is available at Aetrix Electronics and suitable for industrial motor control, appliance electronics, and HVAC subsystems requiring stable component supply across extended production lifecycles.

Supply support for MC908MR8CPE 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) is a global leader in embedded processing solutions, specializing in automotive, industrial, and networking microcontrollers and analog products.

The MC908MR8CPE belongs to the HCS08 microcontroller family, designed specifically for cost-sensitive, real-time motor control and sensor-based embedded systems requiring high peripheral integration and robust operation in electrically noisy environments.

FAQ

What is the maximum bus frequency supported by the MC908MR8CPE?

The MC908MR8CPE supports a maximum bus frequency of 8 MHz, derived from its internal Clock Generator Module (CGM) with PLL. This frequency is confirmed in Section 8.4.2 and Table 21-1 (Electrical Specifications) of the MC68HC908MR8 Rev 4.1 datasheet. At 8 MHz, the MC908MR8CPE delivers sufficient instruction throughput for real-time motor commutation, ADC sampling, and SCI communication without compromising timing precision. The actual achievable bus speed depends on VDD and temperature conditions specified in the datasheet's operating ranges.

Does the MC908MR8CPE include a hardware watchdog timer?

Yes, the MC908MR8CPE includes a Computer Operating Properly (COP) watchdog timer, detailed in Section 15 of the MC68HC908MR8 Rev 4.1 datasheet. The COP is a windowed timer requiring periodic service via the COPCTL register; failure to service within the configured window triggers a hardware reset. It operates independently of the main CPU clock and remains active in Wait mode, providing reliable fail-safe operation for motor control applications where software lockup could cause hazardous motion.

Can the MC908MR8CPE perform simultaneous ADC conversions and PWM updates?

Yes, the MC908MR8CPE supports concurrent ADC conversion and PWM operation. Its 10-bit ADC can be triggered by software, timer overflow, or PWMMC events (Section 18.4.2), and its PWMMC module operates autonomously once initialized. Section 9.9 and 9.10 confirm PWM continues in Wait mode, and Section 18.5 states ADC conversions may proceed during low-power modes if clocks remain enabled. This allows synchronized current sensing and gate drive updates critical for field-oriented control loops.

What debug or programming interface does the MC908MR8CPE support?

The MC908MR8CPE supports serial programming and debugging via its built-in Monitor ROM (MON), accessible through the SCI interface (Section 10). No external debugger or JTAG adapter is required: users connect a UART-to-USB cable to PTB0 (RxD) and PTE2 (TxD), then use Freescale's P&E Micro or similar tools to erase, program, and verify FLASH. The MON also supports command-line diagnostics and register inspection, accelerating bring-up and field firmware updates without additional hardware.

Is the MC908MR8CPE pin-compatible with other members of the MR8 family?

Yes, the MC908MR8CPE is pin-compatible with other 48-pin QFP variants in the MR8 family, including MC908MR8CP, MC908MR8CDT, and MC908MR8CDTE, as confirmed by identical pin assignments in Section 1.5 of the MC68HC908MR8 Rev 4.1 datasheet. Differences between these variants lie solely in packaging (e.g., tape-and-reel vs. tray), temperature grade (-40°C to +85°C for CPE), and minor electrical specs - not pin function or layout. This enables drop-in replacement for logistics or qualification flexibility without PCB redesign.