ESTSS -> DEMO -> Embedded Systems -> LegoBot Controller

Fully Autonomous Legobot
Using Custom Interface Board
With 68HC12 Microcontroller

ECE 345 Project Proposal

Darrel Goeddel
Elizabeth Mason
Nick Shin
Click here to see our senior design presentation.
TA: Sueng-Yong Park
February 14, 1998

Introduction
We propose to build a fully autonomous Legobot using a custom interface board with the 68HC12 microcontroller. Our design was influenced by a previous ECE 291 final project. While the 291 project focused on the programming aspect our project will focus on building the interface board and designing low power consumption hardware. The goal of our project is to have all of the sensors fully operational. We will build a small-scale demo robot to display some of the capabilities.

Design Considerations
Power Motors
We will use the PWM features of the microcontroller to control an H-bridge power transistor configuration. Power MOSFET transistors will be used. The H-bridge will be controlling a higher power supply for the motors.

Analog Signal
We will use the analog inputs of the microcontroller. The A/D converters will be used to acquire signals from the analog sensors. Tentative sensors are reflectance sensors, phototransistors, and potentiometers.

Digital Inputs
We will use the digital inputs of the microcontroller. DIP switches will be used for debugging, microswitches (bump sensors) will be used for obstacle detection enhancement, and infrared receivers will be used for infrared detection.

Digital Outputs
We will use the digital outputs on the microcontroller. A HEX display will be used for debugging and a directional pin is used for each motor.

Other Features of the Microcontroller
We will use the serial port RS232C to connect to the PC for debugging and downloading. The EEPROM will store the program for static code. We will take advantage of the HCMOS design to try and reduce power consumption from 5V to 3V.

Specifications

Power 6V-Motor
5-3V Microcontroller
CPU Speed 8 MHz
Infrared Range 40 KHz
Debugging Hex display - self run mode
Serial mode - development
Analog inputs turned into digital values of 0-255

Timetable

Feb 11-18 Become familiar with microcontroller and its features
Find hardware compatible devices
Feb 18-25 Design for power and digital system outputs
Write code for testing purposes
Begin construction of hardware board
Formal Project Review
Feb 25-Mar 4 Design of analog system
Write code for testing
Mar 3- Mar 11 Finalize design
No optimizations
Debugging and development of demo model
Mar 11-18 Catch up on anything needed
Mar 30 - Apr 8 Optimizing for low power consumption
Debugging
Apr 8-Apr 15 Debugging
Finish construction of demo model

Parts
Motors power MOSFET Reflective object sensors
capacitors Potentiometers resistors
Phototransistors legos DIP switches
serial cable Microswitches batteries and harness
HEX display heat shrink and tubing connectors
sockets bread board

Copyright © 2001 by Nick Shin. All Rights Reserved.
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