The CPU board’s 32-bit microcontroller has 512 kB of flash ROM and 24 kB RAM on-chip memory. Additionally, to meet the demand for the application development phase that requires larger memory, the board has 1 MB of external flash that can be used for code and constant data. The external 2 MB RAM on board can be helpful for external debugging using a monitor debugger. The board offers push buttons for external interrupts and reset signal for microcontroller. There is also an RS232 driver and DB9 connector for internal on-chip UART. In addition to the general-purpose use UART, the board provides connectivity to the PC for monitor/debugger communication or for programming the on-chip flash flash memory. A one-channel CAN transceiver for an on-chip CAN controller is useful for developing a CAN-based system, for example, an ideal environment for gateway application development.
The kit’s main board is used as a baseboard, providing a plug-in for the daughterboard with the FlexRay controller and two physical layer modules with FlexRay transceivers. The physical layer modules are optional components ordered separately from third party developers. The main board carries the power supply for all secondary voltages. It provides connectivity to the host processor and both FlexRay channels via RS485 transceivers. Each communication channel can be configured for the bit-rates up to 10 Mbit/sec.
The daughterboard integrates the Fujitsu FlexRay controller on an Altera FPGA that conforms to the E-Ray specification version 1.1 proposed by Bosch (Version 2.1 will be available soon). The FPGA based communication controller is supplied with an 80 MHz oscillator. The default physical layer for FlexRay communication is provided by two RS485 transceivers mounted on the FlexRay main board. However, these transceivers can be bypassed with physical layer modules that plug into terminals on the FlexRay Evaluation Main Board. Then, instead of the default RS485 transceiver, a true physical layer representation can be established. Also, Fujitsu’s new MB88121 FlexRay controller can be used on the board in place of the FPGA.
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Understanding the E-Ray feature set
To write application software, designers must understand the feature set of E-Ray. The E-Ray module is a FlexRay IP module integrated in an FPGA mounted on the daughterboard. The module communicates according to the FlexRay protocol specification Version 2.1 and its register set can be accessed directly by the CPU via the external bus interface. These registers control, configure, and monitor the FlexRay protocol controllers, along with message handler, global time unit, system universal control, frame and symbol processing, network management, and interrupt control, and access the message RAM via I/O buffer.
Individual message buffers with up to 254 data bytes are configured for communication on the FlexRay network. The message storage consists of 128 message buffers and is configurable for different payload lengths. Each message buffer can be configured as receive buffer, as a transmit buffer, or as a receive FIFO. All functions concerning the handling of messages are implemented in the message handler. These functions include: Acceptance filtering; transfer of messages between the two FlexRay protocol controllers and the message RAM; maintaining the transmission schedule; and provision of message status information. The message filtering supports filtering for frame ID, channel ID, and cycle counter. E-Ray supports the network management function by the global time unit registers that allow configuration of macrotick and microtick for static and dynamic slots.
Because writing the FlexRay communication driver using the E-Ray module can be tedious and time consuming, the kit comes with evaluation copy of the Decomsys library that can be used for time-driven communications. The library provides the developer with ready-to-use functions and enables platform-independent application development. Using these features, the application can access the hardware transparently by using a versatile Applications Programming Interface (API). The device driver provides a frame-based API for the FlexRay communication controller. These API functions perform controller configuration, facilitate read/write accesses to the data buffers of the communication controller, and allow switching the communication controller on and off.
Supplied with the evaluation kit, Softune Workbench V6 is a Windows XP-compatible integrated development environment for the Fujitsu microcontroller. The workbench includes the complete set of tools, editor, C compiler, assembler, linker, librarian, and debugger require for the complete software development cycle.
For engineers to develop specific software and work with the debugger, the Softune Workbench development environment must be installed first.
The kit comes with ready to use sample programs and template that can be modified to generate the real application software. These programs can be compiled/built using the Softune Workbench. Sample programs are available for using the COMMSTACK library and for direct use of the E-Ray module, which gives the developer a chance to evaluate the complexity of a program without the library. A program written using the library requires installation of the library on the project folder to build the program.
After successfully compiling/building the program, these sample programs can be loaded and run directly from the CPU. The user can debug the software immediately using the monitor/debugger that is pre-programmed into the flash memory of the CPU369 board. There is no need for additional tools.
For more extensive software debugging an emulator can be used with the kit. To use an emulator, the designer must remove the MCU-adapter-board with flash MCU and plug in the Starterkit (91360-ADA160), including a socket, which can be ordered separately.
The FlexRay kit is a high performance evaluation and prototyping platform, with the benefits of versatility and expandability that enable rapid, integrated design, simulation, and test system applications for FlexRay uses. Such products will help designers on their way to making FlexRay an industry-standard protocol that someday will enable by-wire applications to replace mechanical systems.
Neelima Chaurasia is senior applications engineer at Fujitsu Microelectronics America. She can be reached at firstname.lastname@example.org.