Date of Award
Bachelor of Engineering Honours
School of Electronic Engineering
Faculty of Communications, Health and Science
The initial aim of this project was to create an ethernet (IEEE 802.3) Communications System. The system was to connect Embedded controllers to facilitate the operation of a real time operation. After extensive investigation and scheduled meetings with industry, it became apparent that a superior communication system for this type of task lay in the Controller Area Network (CAN) standard. Communications Networks are extremely susceptible to volatile surroundings. A vital controller network necessitates that its communication network be invulnerable to high noise levels. It is also imperative that critical messages from one controller reach their destination on time. CAN was conceived by BOSCH as a solution to this dilemma. The project undertaken was to develop a controller area network, whose purpose was to control a solar tracker in a remote fashion. The solar tracker developed needed to be able to work in an autonomous fashion via its own embedded controller, however be able to receive commands from a remote control unit. This remote unit was able to display the status and operation mode of the tracker, yet also be able to issue over ridding commands to the tracker in a real time sense. A CAN network was created and interfaced to a MC68HC11 embedded controller. A two wire differential (RS 485) system was implemented as the physical CAN bus. Every aspect of interfacing the CAN (Intel 82527) device to the HC11 was investigated. Chip Select problems resulted in the simulation of the of the HC11 Address/Data bus using a MC68HC24 Port Replacement Unit (PRU), even the possibility of Serial Peripheral Interface (SPI) connection was considered before a hardware solution was developed. The driver software and low level communication system developed addresses all aspects of operation, from initialisation of the 82527, to dealing with the reception and transmission of various messages. Software to enable simultaneous network communications and solar tracking operation was completed for the solar tracking device. Every message object type was utilised within the system. The generation interrupts to deal with the reception of critical messages, and other message prioritisation schemes were incorporated. The resulting system demonstrated that the controller was able to drive a solar tracking panel and receive additional commands and issue status reports to a remote micro controller, in a real time situation. Such a system as this could have many solar trackers connected to the same bus and result in a cheap but reliable installation. Alternatively virtually any Industrial distributed automated process confined within a relatively close proximity could be developed by using a derivative of such a system described within this report.
Wilkinson, B. (1998). Networking 8-bit embedded controllers, using the controller area network method. Retrieved from http://ro.ecu.edu.au/theses_hons/736