Automakers and Tier 1 providers are faced with increasingly complex safety, powertrain, chassis and body systems that are often designed to work in concert. Emerging systems, such as x-by-wire, collision avoidance and driver assistance require a network that delivers very high data rates in a predictable and reliable way.
MOST can support high data rates; however, it's a network standard that is designed specifically to connect in-vehicle multimedia. CAN networks are capable of connecting several ECUs, but at a typical data rate of only 500 Kbps to 1 Mbps. Also, CAN employs priority arbitration for message delivery, meaning lower priority messages will always be delayed by higher priority messages. Only the highest priority message is assured delivery.
CAN's relatively low data rate and lack of fault-tolerance make it inadequate for advanced applications, such as x-by-wire. LIN is essentially an inexpensive and comparatively slow sub-network to CAN, and it simply cannot handle the data rates required by the advanced safety systems expected in next-generation vehicles.
FlexRay™ technology is a deterministic, dual-channel architecture with 10 Mbps gross data rate per channel. With both channels operating independently, the aggregate data rate is 10 Mbps—up to 10 times that of a CAN network. Deterministic simply means that nothing is left to chance. FlexRay is time-triggered and completely predictable, regardless of outside influences. This is critical for safety applications that require consistent and extremely reliable high-speed performance.
Freescale is a founding member of the FlexRay Consortium, and we have the products and expertise that enable product developers to implement the FlexRay protocol in next-generation in-vehicle applications. Our solutions include the MC9S12XF family, MPC5561 and MPC5567 microcontrollers with embedded FlexRay modules.
Electromechanical braking systems (EMB), also known as brake by-wire, replace conventional actuators with electrical motor-driven units to connect the vehicle's four braking "corners" to the pedal and to each other. An EMB system also eliminates the use of large vacuum boosters and provides better control of pedal stiffness, traction control, vehicle stability and brake force distribution than those found in conventional hydraulic systems. While conventional hydraulic braking systems have a mechanical or hydraulic backup, an EMB braking system does not. Therefore, reliability in an EMB system is absolutely critical and the system must use a fault-tolerant communication protocol, such as FlexRay.
The Freescale S12XF family of processors adds FlexRay protocol to our proven 16-bit S12X MCU architecture, delivering FlexRay technology and MCU performance in a single device. In addition to the safety benefits described above there are also economic and environmental benefits to FlexRay systems.