Freescale公司的MM912_S812是S12XS MCU和多功能點火和噴油器驅動系統，SiP集成了MCU（S12XS）和模擬控制芯片（MC33812），專門設計用于摩托車和其它單/雙缸小引擎控制應用。工作范圍4.7 V ≤ VPWR ≤ 36 V，繼電器/點火/油泵驅動器電流4A，燈驅動電流1.5A， ISO-9141 K線收發器用于通信診斷信息。本文介紹了MM912_S812主要特性， MC9S12XS系列框圖和33812簡化內部框圖， MM912_S812詳細應用框圖以及小型引擎參考設計KIT912S812ECUEVM主要特性和系統建立圖， 小型摩托車引擎控制系統框圖， 參考設計板KIT912S812ECUEVM系統框圖，電路圖，材料清單和PCB元件布局圖。

The MM912_S812 is an engine control IC combining an MCU （S12XS） and analog control die （MC33812） intended for motorcycle and other single/dual cylinders small engine control applications. The MCU S12XS has 8.0 KB or 12 KB RAM， and flash memory size of 128 KB or 256 KB. The S12XS family retains many of the features of the S12XE family including error correction code （ECC） on flash memory， a separate data-flash module for code or data storage， a frequency modulated locked loop （IPLL） that improves the EMC performance and a fast ATD converter.

MM912_S812主要特性：

?Designed to operate over the range of ~4.7 V ≤ VPWR ≤ 36 V

?Relay/injector/fuel pump driver – current limit – 4.0 A， typical

?Lamp driver – current limit – 1.5 A， typical

?All external outputs protected against short to battery and overcurrent

?VCC voltage pre-regulator provides +5.0 V power for the MCU

? MCU watchdog timer circuit with parallel refresh/time setting line

? ISO-9141 K-Line transceiver for communicating diagnostic messages

圖1. MC9S12XS系列框圖

圖2.33812簡化內部框圖

圖3. MM912_S812簡化應用框圖

圖4. MM912_S812詳細應用框圖

小型引擎參考設計KIT912S812ECUEVM

Welcome to the Freescale Small Engine Reference Design Kit. This product was designed to be a complete solution for the electronic control of a small engine. Small engines are defined as a one or two cylinder engine for use in anything from a motorbike to a lawn mower to a generator. While the decision was made to address a one-cylinder engine specifically， this design is extremely useful for a two-cylinder engine with little or no modification. Freescale’s concept of creating an engine control kit is intended to enable a market ranging from garage hobbyist to seasoned Tier 1 Powertrain Engineer using Freescale products.

Through the use of this kit， you can create an engine controller specific to a small engine application. Engine control is a discipline that requires intimate knowledge and experience in Chemical， Mechanical， and Electrical Engineering. For those familiar with mechanical control of an engine through a carburetor， the use of this reference design kit can help to advance your knowledge in the electrical area and provide a jump-start for a successful adoption of electrical engine controls to meet new emissions standards. Providing a kit such as this is intended to make semiconductor products from Freescale easier to use. The user is responsible for providing all input signals， output loads as well as the completed system design and development. This kit should serve as a starting point for the development of an application specific engine controller for a small engine. Example software and documentation are provided to assist in successful design and implementation. It is recommended to have the following skills and experience： embedded C-language programming， analog and digital circuit design and schematic analysis， microcontroller programming， fuel injection system debugging and calibration， and engine test environment experience. Additionally， there is further benefit to experiencing the CodeWarrior Development Studio and the Freescale S12X microcontroller Units （MCUs）。 The User Reference Manual provides exercises and references to additional information to reduce the learning curve for inexperienced users.

Freescale’s goal is to enable the small engine market. To clarify this point， the hardware included in this kit can readily be configured and reprogrammed to run an engine. However， it lacks the application specific hardening （EMC， ESD， and environmental areas for example） and implementation optimization that make it a production ready module for any specific application. Further， the free example application software provided is a starting point capable of running an engine. It does not apply any advanced control strategy capable of addressing the pollution concerns and regulations facing the small engine industry. To do this would become application specific to an engine and could not be and should not be implemented by a semiconductor supplier as it is deeply outside their area of expertise. The example application software does show how to use the key functionality in the Freescale products that the kit is based on， which speeds up the development process by showing a working example.

The contents of this kit will save many months of work， even for experienced powertrain engineers just looking to evaluate Freescale products. A system has been created based on a one-cylinder closed-loop engine controller using integrated technology while being cost-effective for the small engine market. Example software is provided that can be customized to run an actual engine that has electronic fuel injection. Documentation is provided to aid in going through the process of developing an application. Finally， information on modifying the design to support the adaptation of the small engine reference design to your application goals.

圖5.參考設計板KIT912S812ECUEVM外形圖

參考設計KIT912S812ECUEVM包括：

?Assembled and tested KIT912S812ECUEVM board in anti-static bag.

?ECU wire harness

?USB BDM Tool

?6-pin ribbon cable

?A-to-B USB cable

?Warranty card

圖6.參考設計板KIT912S812ECUEVM建立圖

圖7.小型摩托車引擎控制系統框圖

圖8.參考設計板KIT912S812ECUEVM系統框圖和系統負載

圖9.參考設計板KIT912S812ECUEVM電路圖(1)

圖10.參考設計板KIT912S812ECUEVM電路圖(2)

圖11.參考設計板KIT912S812ECUEVM電路圖(3)

圖12.參考設計板KIT912S812ECUEVM電路圖(4)

圖13.參考設計板KIT912S812ECUEVM電路圖(5)

圖14.參考設計板KIT912S812ECUEVM PCB元件布局圖:頂層

圖15.參考設計板KIT912S812ECUEVM PCB元件布局圖:底層

參考設計板KIT912S812ECUEVM材料清單: