Explore the key features, including wide voltage operation, robust protection mechanisms, and direct MCU interfacing, that make this reference design a comprehensive solution for single-cylinder engine control.
The Small Engine Reference Design is a compact hardware solution that controls single-cylinder engines. It is based on a combination of the company’s semiconductor components, including the MC9S12P128 microcontroller, the MC33812 Small Engine Integrated Circuit, and the MC33880 Configurable Octal Serial Switch. A 12 V battery powers this unit and can control various engine loads such as fuel injectors, inductive ignition coils, relays, incandescent lamps, and LEDs.
Regarding inputs, the Engine Control Unit (ECU) accepts signals from switches and sensors, including an Engine Stop switch, manifold air pressure sensor, engine temperature sensor, and variable reluctance sensors. The application software that runs on this unit contains the engine control strategy, which is crucial for the engine’s proper functioning. Although this reference design is not intended for production purposes specific to any engine, it aims to provide a look and feel similar to that of a production module. Its compact size, resembling that of a business card, and its minimal provision for expansion are notable features.
This reference design, KIT33812ECUEVME by NXP, is a fully functional single-cylinder engine control unit equipped with various key features to ensure reliable and efficient operation. It supports the company’s 33812 and 9S12P128 MCU devices and can be configured for dual-cylinder engines, although it requires the application to tolerate simultaneous sparks in both cylinders. The unit operates over a wide voltage range of approximately 4.7 V to 36 V. It includes a fuel injector driver with a typical current limit of 4.0 A, an ignition pre-driver that can drive IGBT or Darlington bipolar junction transistors, and relay and lamp drivers with current limits of 4.0 A and 1.5 A, respectively.
The external outputs are protected against short-circuiting to the battery and over-current to ensure safety and durability. In contrast, the ignition and other drivers are protected against over-temperature conditions. The unit directly interfaces with the MCU using a 5.0 V parallel interface and features a VCC voltage pre-regulator that provides +5.0 V power for the MCU. Additional functionalities include an MCU Power On RESET generator, an MCU watchdog timer circuit, and independent fault annunciation outputs for ignition and injection. For debugging purposes and communicating diagnostic messages, the design incorporates an ISO-9141 K-Line transceiver. Overall, this reference design offers a comprehensive solution for controlling single-cylinder engines, with a range of features and protections to ensure efficient and reliable operation.
NXP has tested this reference design, which comes with a bill of materials (BOM), schematics, and other data. The company’s website has additional data about the reference design. To read more about this reference design, click here.
