Chassis/Safety Electrohydraulic Braking Overview Electrohydraulic braking (EHB) systems are designed to allow electronic control of vehicle braking while retaining a reduced hydraulic system. The hydraulic system functions as a reserve in the event of a failure in the electronic control. The EHB control unit receives inputs from sensors connected to the brake pedal. In normal operation, a backup valve is closed and the controller activates the brakes of the wheel through an electric motor driven hydraulic pump. When the controller goes into a fail-safe mode, the backup valve is opened, which allows the brakes to be controlled through a conventional hydraulic circuit. > Uses software updates to simplify the calibration process by adjusting brake response and pedal feel ELECTROHYDRAULIC BRAKING BLOCK DIAGRAM Pedal Sensor Hydraulic Pump EHB Control Unit · MCU · Output Driver Hardware Accumulator Key Benefits > Reuses hydraulic system technology while incrementally building on the development of advanced electronic systems, such as electronic stability programs (ESP), traction control, and brake assist > Improves connectivity with other emerging systems, such as adaptive cruise control > Removes the large vacuum servo to allow flexible installation > Features an anti-lock braking system (ABS) without feedback from the pedal Backup Valve Hydraulic Brake Actuators Freescale Ordering Information1 Part Number Product Highlights Additional Information MPC500 32-bit microcontrollers www.freescale.com2 SMARTMOS Integrated circuits www.freescale.com/analog Notes: 1. Contact your Freescale Semiconductor sales representative for complete information about existing products and custom solutions. 2. Search on the listed part number. Design Challenges Electrohydraulic braking is based on existing ABS systems with the addition of several enhancements. The inclusion of analog electrohydraulic valves requires closed-loop, current-controlled pulse width modulation (PWM) outputs from the electronic control unit (ECU). Freescale Semiconductor Solution An EHB system requires mid-range performance MPC500 microcontrollers for system control with SMARTMOS companion chips for functions such as load driving, sensor interfacing, voltage regulation, and system watchdog operation. An EHB system is required to incorporate a fail-safe state in the event of a fault occurring. To correctly initiate the fail-safe state, the system relies on its electronic components to provide a high level of operational fault coverage. Freescale Semiconductor has gained experience developing many of the specific aspects required for the implementation of an EHB system. Because of its extensive experience in the development of fail-safe microcontrollers, braking-specific modules such as the wheel speed timer, and a software center including drivers, tools, and operating systems, Freescale Semiconductor has proven its ability to develop the right solutions in collaboration with its customers. Development Tools Vendor MPC555 MPC561 MPC562 MPC563 MPC564 MPC565 MPC566 CodeWarrior for Embedded PowerPC ISA ! ! ! ! ! ! ! CodeWarrior for OSEK RTOS ! ! ! ! ! ! ! CodeWarrior Development Systems ! OSEKturbo (RTOS) ! TPU Metrowerks ! ! ! ! TPU Low-Level Driver Library ! Flash Programming — CodeWarrior for Embedded PowerPC ISA ! ! ! ! ! Flash Programming — CodeWarrior for OSEK RTOS ! ! ! ! ! Wind River Systems BDM Debugger — SingleStep ! ! ! ! BDM Debugger — SingleStep with Vision ! ! ! ! Flash Programming — SingleStep ! ! ! BDM Debugger — VisionCLICK ! ! ! ! ! ! ! ! ! ! Nexus Debugger — VisionCLICK Nexus Debugger — SingleStep with Vision Flash Programming — VisionCLICK ! Compiler — DiabData ! ! MATRIXX ! ! Simulator — SingleStep ! ! SG2007-2 ! ! ! ! ! ! ! ! ! ! ! ! ! ! Development Tools (continued) Vendor MPC555 MPC561 MPC562 MPC563 MPC564 MPC565 MPC566 TPU ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! Lauterbach BDM Debugger Trace32 Nexus Debugger Trace32 Code Trace (with Bus access) ! ! ! ! ! ! ! Code Trace (Nexus) ! ! ! ! ! ! ! Low-Cost Evaluation Board ! ! Mid-Range Evaluation Board ! ! Full-Feature Evaluation Board ! ! ! ! ! ! ! ! ! ! ! ! ! ! Axiom Manufacturing Ashling Microsystems BDM Debugger — Opella, Genia, and Vitra Nexus Debugger — Vitra (w/trace) ! ! ! Nexus Debugger — Opella, Genia ! ! ! ! Green Hills Software IDE, Debugger — Multi ! ! ! ! Compiler — C/C++/EC++ ! ! ! ! Low-Cost Debugger ! ! ! ! Flash Programming Tools ! ! ! ! ! P&E Microcomputer Systems GNU Compiler/Debugger ! ! ASH WARE TPU Simulator ! ETAS ErCOSEK ! ! ! ! Calibration Tools (ETK) ! ! ! ! Calibration Tools (ETK) Nexus ! ! ! ! ! ! ! ! ! ! ! ! Logic Analyzer ! ! ! ! Inverse Assembler, Source Correlation ! ! ! ! Emulation Probe (BDV) ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! dSPACE TargetLink dli Logic Analyzer Agilent Technologies Tektronix Logic Analyzer Abatron AG BDM Support Accelerated Technology Nucleus (RTOS) SG2007-3 Third Party Support Vendor Contact Information Metrowerks 800-377-5416 (www.metrowerks.com) Axiom Manufacturing 972-926-9303 (www.axman.com) Wind River Systems 800-872-4977 (www.windriver.com) Green Hills Software 805-965-6044 (www.ghs.com) Lauterbach 508-303-6812 (www.lauterbach.com) Accelerated Technology 800-468-6853 (www.acceleratedtechnology.com) Ashling Microsystems 408-732-6490 (www.ashling.com) ASH WARE 503-533-0271 (www.ashware.com) GNU 617-542-5942 (www.gnu.org) ETAS 888-382-7462 (www.etasinc.com) dSPACE 248-567-1300 (www.dspace.com) P&E Microcomputer Systems 617-353-9206 (www.pemicro.com) Online Topics Description Location MPC500 www.freescale.com Analog and Mixed Signal www.freescale.com 32-Bit Development Tools www.freescale.com Related Product Product Number Product Name Contact Information MPXV6115V High temperature accuracy integrated silicon pressure sensor — small outline package www.freescale.comNote Note: Search on the listed part number. Learn More: Contact the Technical Information Center at +1-800-521-6247 or +1-480-768-2130. For more information about Freescale products, please visit www.freescale.com. Freescale™ and the Freescale logo are trademarks of Freescale Semiconductor, Inc. All other product or service names are the property of their respective owners. © Freescale Semiconductor, Inc. 2004. All rights reserved. SG2007 REV 1 12/2004 December2004