Spacecraft designers at Surrey Satellite Technology Ltd. (SSTL) in Guildford, England, needed a control module for the Controller Area Network bus (CAN bus) used in the company’s SGR-05P range of space-borne global positioning system (GPS) receivers. They found their solution in the Controller Area Network Intellectual Property core CANmodule-IIx from Inicore Inc. in Newark, Calif.
The first flight-ready incarnation of the SGR-05P-based receiver is called the SGR- 07, a stand-alone, packaged version of the SGR-05P with power and communications interfaces. UK-DMC-2 is an Earth observation satellite involved in disaster monitoring.
The SGR-07 communicates with the rest of the satellite exclusively over the dual-redundant CAN bus using the CANmodule-IIx. Surrey Satellite engineers have finished testing the SGR-07 onboard the company’s UK-DMC-2 satellite. CAN bus is a differential two-wire interface running over either a shielded twisted pair, unshielded twisted pair, or ribbon cable. The bus moves data at rates from 10 kilobits per second to 1 megabit per second. At its fastest, the databus is similar to MIL-STD-1553.
CANmodule is a CAN bus controller with advanced message filtering and receive and transmit buffers. It is designed for advanced system-on-chip devices, where a 32-bit microprocessor powers the system. Full message filtering together with a prioritized transmit queue supports a wide range of applications.
“The CANmodule-IIx core with its standard AMBA APB system bus interface is designed for a smooth system integration,” says Hans J. Kuffer, Inicore’s vice president of business development. “Although the target FPGA [field-programmable gate array] was for a satellite-based application, it was impressive to see how quickly SSTL completed the core integration.”
The CANmodule-IIx core is ISO 11898-1 compliant and supports the CAN standard and extended-frame formats. The FIFO-based architecture features three hardware message filters, which enable back-to-back message reception with minimal CPU interaction. The system interface supports the industry-standard AMBA APB bus, making it easy to integrate. Several synthesis configurations are available to obtain a gate-count optimized FPGA implementation.
For more information, visit Surrey Satellite Technology online at www.sstl.co.uk, or Inicore at www.inicore.com.
