CAN User Interface

The goal is to design a user interface device that is able to control and show information from CAN devices in real time, and also functions as a bridge between PC and CAN devices. CAN devices are devices that contain a CAN interface for controlling their functions or reading their properties. Such devices are for example motor control and sensors boards.

The nodes of the overall system are shown in the figure above. The students will develop the CAN User Interface (CANUI) device. The device contains a display, buttons and some knobs for the user interface and menu system. With these components the user can control a menu system of the device. The device contains also a serial port and the CAN user interface. Serial port is used for connecting to PC. PC can control the CAN devices with simple ASCII commands using a terminal program (hyperterminal on Windows XP). The can devices can return data that is converted into ASCII format for viewing on the terminal.

The CAN interface is used for controlling the CAN devices. CAN devices in this course are two devices, one controlling two servomotors and the other lights and temperature sensor. The motors, lights and sensors are controllable via CAN protocol messages that the CANUI device sends to the CAN devices. The format of the messages is given here. The CAN protocol specification is available on the course web page here

	//Set SJW = 1TQ, TQ = 1000ns
	//For 20MHz, BRP = 9
	//For 16MHz, BRP = 7
	//For 8MHz, BRP = 3
	//For 4MHz, BRP = 1

	CNF1 = 2

	//BLT mode, PS1 = 3, PRSEG = 1
	CNF2 = (1<<7) | (2<<3) | 0;

	//PS2 = 3
	CNF3 = 2

These settings result can bit time of 8*1000ns i.e. 125kHz baud rate.

The basic requirements for the device are the following:

• The serial interface works from MCU to PC. The unit sends data to the PC in a readable form. The data is read in PC with some regular ASCII based terminal program such as Hyper Terminal. Data must be readable in real-time.
• The serial interface works from PC to MCU. At least menu and some CAN commands must be possible to be controlled from PC.
• Menu buttons can be used to operate the device.
• LCD display shows menu and some information, at least the current menu state and some current control values.
• The device gets 3.3 volt operating voltage from a 12 volt DC power source. The device must feed the 12 volts to other CAN devices.
• The device is able to control at least two CAN devices simultaneously.

These are also the basic grading points. Additional points can be received from additional features that demonstrate utilizing different features of the MCU. You may include also following optional features, such as:

• PC data visualization for measurements
• SD card for data logging

The CAN User Interface will be based on an Atmel ATmega series microcontroller (MCU). The students are recommended to use ATmega32 controller. The control module is required to contain the following on-board components:

electronics needed to support required functions

Each group will receive

• The serial cable connector
• LCD display (optrex F-51553)

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Serial cable connector, 5 pin 2,54mm raster socket for pin header. Notice 2 empty orientation slots.

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CAN light control box. Notice that your device must supply the 12 volts for the CAN light control box. The CAN connector is a 5-pin header, 2.54mm raster. Fourth pin is unconnected.

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CAN servo control box. Notice that your device must supply the 12 volts for the CAN servo control box. The CAN connector is a 5-pin header, 2.54mm raster. Fourth pin is unconnected.