Abstract: Increasingly stringent global automotive emission regulations place higher demands on engine management systems: higher control precision, more complex control functions, and comprehensive on-board diagnostics (OBD) capabilities. Freescale Semiconductor addresses these challenges by presenting a reference design for an Electronic Control Unit (ECU) based on the MPC5500 series 32-bit Power Architecture microcontroller and the next-generation SMARTMOS™ intelligent power device. Keywords: Engine management system; Electronic control unit (ECU); Freescale; MPC5500; SMARTMOS intelligent power device Introduction Modern advanced engine management systems have achieved high levels of fuel economy and emission control, with the software and hardware performance of the Electronic Control Unit (ECU) being crucial. Freescale Semiconductor, a leading global supplier of automotive electronic semiconductors, provides powertrain system solutions including microcontrollers (MCUs), sensors, power management devices, power drive devices, and real-time operating systems and underlying driver software compliant with the AUTOSAR (AUTomotive Open System Architecture) standard. This design can be applied to gasoline engine management systems, diesel high-pressure common rail fuel injection systems, automatic transmission and CVT control systems, hybrid power systems, and fuel cell control systems. This article introduces a reference design for a gasoline/diesel engine electronic control unit (ECU) based on the MPC5500 series 32-bit Power Architecture microcontroller and the next-generation intelligent power device SMARTMOSTM. Engine ECU Reference Design System Framework Taking a typical gasoline engine control system as an example, Freescale's reference design system framework is shown in Figure 1. On the left side of Figure 1 are the signal inputs: analog signals output from sensors such as temperature, pressure, accelerator pedal, and throttle position are filtered and acquired by the MPC5500's high-speed analog-to-digital converter (ADC) module; frequency signals such as crankshaft angle, camshaft timing position, and vehicle speed are acquired and processed by the MPC5500's eTPU module; the high-frequency signal output from the knock sensor is sampled by the high-speed ADC within the crankshaft angle window determined by the eTPU, and then filtered and integrated by software algorithms to achieve on-chip software knock detection, saving the cost of a dedicated knock processing chip for the system. Switch signals such as air conditioning request switch, external load engagement, brake pedal, and clutch status are collected by an intelligent switch detection chip and transmitted via the SPI interface, saving MCU I/O resources. This chip also has a maximum 32mA wet current output function, which can be used to protect the switch contact surfaces from oxidation. Engine operating condition signals collected by various sensors are provided to the complex control software inside the main MCU to calculate and determine control parameters such as fuel injection and ignition, and execute the output. The right side of the diagram shows the signal output: each intelligent power drive device supports both parallel and SPI serial driving modes. SPI is also used to exchange configuration parameters and fault diagnosis information with the MCU. High-frequency signals (such as fuel injection and ignition pulses) are all driven in parallel. • 32-bit main microcontroller: 32-bit Power Architecture MPC5500 series • 8-bit monitoring microcontroller: MC9S08SG8 • Smart power devices SMARTMOS™ - Communication interfaces MC33902: High-speed CAN bus transceiver MC33661: LIN bus transceiver - Power drive MC33800: Multi-functional smart power drive chip MC33810: 4-channel injector driver and ignition coil IGBT pre-drive chip, multiple chips can be connected in parallel for different 6-cylinder/8-cylinder applications. MC33926: H-Bridge driver chip (for electronic throttle control) - Signal monitoring; MC33975: 22-channel switch quantity detection chip with sleep wake-up and 32mA wet current output function; MC33811: 5-channel electromagnetic coil load monitoring chip - Power management; MC33730: Board-level power management chip. The MPC5500 product family, designed for powertrain systems , is a new generation of microcontrollers developed for powertrain applications. Its predecessor is the already mature MPC500 family. Based on the high-performance Power Architecture e200 RISC core, the MPC5500 series offers a range of products covering high, medium, and low-end applications. It features a maximum bus frequency of 180MHz, integrates up to 3M bytes of ECC-enabled Flash memory, supports 100k Flash block erase/write cycles, and up to 20 years of data retention. The first product in the MPC5500 series, the MPC5554, has shipped over two million units worldwide. The MPC5500 series boasts excellent software and hardware compatibility. Chips of different models but with the same pinout guarantee 100% pin compatibility, while chips of the same model but different packages (208pin/324pin/416pin BGA) maintain full software compatibility, greatly facilitating platform development and product serialization. In the initial project phase, users can choose chips with abundant on-chip resources and pinouts for prototype design. Once the product is largely finalized, a chip with the best performance-to-price ratio can be selected for production based on actual I/O and Flash resource requirements. Software and hardware porting requires minimal additional workload and also helps control BOM costs. The eTPU is a module dedicated to timing and frequency signal processing, and its internal RISC coprocessor can run independently of the CPU. Freescale provides an eTPU function library for engine control applications, such as crankshaft angle measurement, fuel injection pulse output, ignition pulse output, and camshaft phase detection, allowing users to focus on designing the engine's own control algorithms. The SMARTMOS MC33800 is an intelligent power drive chip designed for engine control applications . It integrates multiple functions, including: two programmable constant current source drives with superimposed current jitter control, suitable for driving automatic transmission actuator solenoid valves; eight low-side switches, with channels 1 and 2 having higher drive current (6A) for driving inductive loads such as indicator lights, and the remaining channels for driving relays or solenoid valves. Adjacent channels can be connected in parallel (e.g., 1/2, 3/4) to increase drive capability; and drive via parallel or SPI serial communication. It also features six MOSFET pre-drives supporting PWM output, which can be used to drive fuel pumps, cooling fan motors, oxygen sensor heaters, EGR or canister purge solenoid valves. Furthermore, it integrates load resistance measurement functionality for load diagnostics of heated oxygen sensors (HEGO). This chip features overvoltage, undervoltage, and overheat protection. Its output drivers and switches offer overcurrent protection, open-circuit detection, short-circuit detection, and SPI fault feedback. The MC33810 is a chip that integrates both injector driver and ignition coil pre-driver. Its high integration saves on board space and reduces component count, making it ideal for four-cylinder gasoline engines. Output channels include: 4 low-side switches for direct injector driving; and 4 (IGBT/MOSFET) pre-drivers supporting PWM output. These can be used to drive IGBTs to control the ignition coil or as general-purpose PWM output drivers for MOSFETs. When configured as an IGBT pre-driver, it also provides detection of primary coil closing time, ignition time, and ignition coil secondary current. This chip features overcurrent, overheat, and power supply short-circuit protection. Its output drivers offer open-circuit detection, short-circuit detection, and SPI fault feedback. The MC33811 is an intelligent chip with 5-channel electromagnetic coil load monitoring. It determines whether the current load is working properly by detecting and analyzing the current waveform through the coil, sets the operating mode via the SPI port, and returns the detection results. In engine control applications, the diagnostic functions provided by the MC33811 can promptly report injector faults to prevent engine damage. It can also be used in other applications requiring solenoid valve diagnostics, such as transmission controllers or solenoid valve controllers. The MC33926 is an H-Bridge intelligent power driver chip with a 5A current output, meeting the stringent requirements of automotive operating environments. Typical applications include engine electronic throttle motor control, but it can also be used for general bidirectional DC motor control, such as EGR solenoid valves. The MC33926 features output current limiting to protect the motor, output short-circuit protection to power supply or ground, and over-temperature shutdown protection with hysteresis. It also includes output current feedback to achieve closed-loop motor speed regulation or torque control. AUTOSAR-compliant RTOS and Low-Level Driver Software Support Freescale Semiconductor, as the first semiconductor device supplier to join the AUTOSAR organization, provides low-level driver software and real-time operating systems compliant with the latest AUTOSAR R2.1 specification. As AUTOSAR matures and is increasingly adopted by major automotive manufacturers and Tier 1 component suppliers worldwide, Freescale is ready to provide users with support for design applications at all levels. Freescale's AUTOSAR basic software package includes: Microcontroller Abstraction Layer (MCAL) drivers, I/O Hardware Abstraction Layer (IAL) drivers, and EEPROM-based memory hardware abstraction layer (IAL) drivers. Currently, the products support the S12X, MPC556X, and MPC551X microcontroller platforms and are continuously being updated and expanded. On the operating system side, a 4-level customizable real-time operating system compliant with the AUTOSAR specification is provided. • SC1—Deterministic RTOS foundation (tasks, events, counters, alarms, messages) • SC2—Time-based task management (low-latency, precise timing for periodic tasks) • SC3—Task-level memory protection (MMU/MPU) to avoid memory conflicts in the security system • SC4—Task-level time and memory protection, fully utilizing chip functionality to provide security protection for automotive RTOS Reference Design PCB Layout Conclusion This article introduces Freescale's engine control unit reference design based on the MPC5500 and intelligent power devices. While meeting the complex control requirements of modern engines, it also brings significant design advantages to users: * Meets the voltage and current specifications of loads and devices in typical engine control applications; * Integrated on-chip diagnostics and monitoring functions contribute to system functional integrity and maintainability; * Highly integrated devices enable simplified board routing and compact layout; * The MCU communicates with peripheral devices via parallel or SPI serial communication, enabling flexible and convenient control connections; * Integrates special functions and features designed for engine control applications; * 32-bit MCU The family's excellent compatibility and scalability facilitate platform development and product series design for users. Building upon the hardware reference designs, Freescale has also developed AUTOSAR-compliant low-level driver software and real-time operating systems, providing users with system-level application solutions and design support.