Microcontroller functions
In order to deal with the new range of
system requirements, the automotive microcontroller will be further
developed to facilitate new functions.
Communications
Communications between electronic control units (ECU's) is a growing trend. Multiplexed communications in vehicles was originally developed to reduce weight, interconnections, cost and complexity. It soon became apparent however that vehicular systems could be enhanced greatly with the opportunity to share data from different ECUs, in real time.
Unfortunately, a single communications protocol, which can cost-effectively address every automotive application, does not exist. Instead a number of different communications subsystems are integrated together in a modern vehicle. This is illustrated in Figure 2.
Figure 2 shows five distinct communications systems, which are implemented on a vehicle. In addition it is likely that there will be a number of additional 'sub-bus' networks for sensors and actuators. Gateways exist between these networks to share information across 'boundaries'. The chassis control functions are grouped on a redundant network, which meets fault tolerant criteria; only safety critical information is allowed on these buses. Likewise a highly robust independent network is provided for the airbag system.
Many new automotive microcontrollers will have more silicon devoted to communications capabilities than the CPU! Already, microcontrollers such as the M68HC912DG128 are being offered with two independent CAN (Controller Area Network) modules along with several more synchronous and asynchronous communications systems. These communications interfaces are as autonomous as possible, so that the CPU does not need to devote a great deal of overhead to managing communications.
Communications
Communications between electronic control units (ECU's) is a growing trend. Multiplexed communications in vehicles was originally developed to reduce weight, interconnections, cost and complexity. It soon became apparent however that vehicular systems could be enhanced greatly with the opportunity to share data from different ECUs, in real time.
Unfortunately, a single communications protocol, which can cost-effectively address every automotive application, does not exist. Instead a number of different communications subsystems are integrated together in a modern vehicle. This is illustrated in Figure 2.
Figure 2 shows five distinct communications systems, which are implemented on a vehicle. In addition it is likely that there will be a number of additional 'sub-bus' networks for sensors and actuators. Gateways exist between these networks to share information across 'boundaries'. The chassis control functions are grouped on a redundant network, which meets fault tolerant criteria; only safety critical information is allowed on these buses. Likewise a highly robust independent network is provided for the airbag system.
Many new automotive microcontrollers will have more silicon devoted to communications capabilities than the CPU! Already, microcontrollers such as the M68HC912DG128 are being offered with two independent CAN (Controller Area Network) modules along with several more synchronous and asynchronous communications systems. These communications interfaces are as autonomous as possible, so that the CPU does not need to devote a great deal of overhead to managing communications.
Figure 2 - The networked vehicle
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