Understanding Smart Sensors - Nomads.usp

144 Understanding Smart Sensorsnetworks that use different protocols. In some cases, custom hardware and softwaregateways convert information from one system’s language to that of theother system. Ideally, the MCU in this node has one or both protocols thatallow an easy transition. In the worst case, the MCU uses a separate peripheralfor each protocol. Figure 6.14 shows the gateway master from the CAN to anMI-Bus. On the master side, the SCI protocol common to many MCUs can beused. On the other side of the gateway, the MCU has a CAN module for communicationon the CAN network. That allows control information to passfrom the CAN network across to drive the output loads. On the slave side, theI/O controller provides the interface to the load. A stepper motor controller,the MC33192, was the first device to control loads in an automotive environmentusing the MI-Bus [26]. The integrated device has both the MI-Bus controllerand a dual full-bridge driver for the stepper motor. Other modules caneasily be designed to control other loads by simply revising the output portionof the MI-Bus device.6.9.3 Transition Between SystemsA gateway can provide security and safety for control systems. Modern vehiclesprovide a unique environment for communications, computer, andControlledoutputsFanCompressorIOCHeating unitIOCIOCInputs:TemperatureHumiditySettingCarbon monoxideAirinletdamperSMCMI-BusGatewayMCUSteppermotorINTCANFigure 6.14 CAN to MI-Bus gateway and various sensors and loads.