The Miniboard costs about 80 dollars. It is a Motorola 68HC11E2 based circuit board. It's features are: 
	o drives four DC motors or two stepper motors (.6 amps max)
	o 8 analog channels, converted to an 8 bit digital word
	o 8 digital lines as any combination of inputs or outputs
	o Operates on a 5 to 36 volt supply
	o serial line communications (RS 232 standard)
	o can talk with other Miniboards as a distributed system
	o 2 Kbytes of program memory in EEPROM
	o 256 bytes of RAM
	o 8 timers or counters
By using sensors to detect the environment and actuators to affect the environment, the Miniboard can be programmed to implement an autonymous robot. Sensors and actuators are not part of the Miniboard itself. Rather the implementor is responsible to find a set of sensors and actuators that he/she thinks will contribute well to a robot. Examples of sensors include photo-resistors and infrared emitter detectors used to detect changes in lighting levels or color contrasts, shaft encoders to detect shaft rotational velocity or rotational position, lever - push switches to detect collision with or proximity to a wall, sonic rangers to detect distance to wall, hall-effect sensors to detect presence of a magnetic field and the list goes on. Examples of actuators include dc motors or stepper motors to rotate a shaft, servo motors to push or pull an implement, heaters to raise temperature, and LED's to emit light (as for an message indication). People who sell the stuff.

Learning to program a 6811 in assembly language represents the largest mental challenge to a Miniboard system designer. Learning to program a Miniboard with the C language is loads simpler! (you would for instance, compleatly avoid learning about interrupts.) This report focuses heavily on assembly programming.

In order to program a 6811 in assembly language, one must understand the memory map of the 68HC11E2, the 6811 programmer' s model, the instruction set & addressing modes, how timers operate, how interrupts operate, and how to gather input and affect outputs. The best strategy for learning is to take the above topics in order, gaining a summary knowledge of each before moving onto the next item. Learning the memory map, programmer's model and instruction set should be done on a simulator rather than on a Miniboard. Learning the timing system, interrupt system, and input gathering and output causation, require the use of an actual Miniboard. Starting out the learning process on a simulator greatly simplifies the learning process and reduces the complexity of what you are trying to learn in a useful way for beginners.

ieeecs@hal.elee.calpoly.edu
BackBack to Table of Contents