| Darrel Goeddel Elizabeth Mason Nick Shin |
Click here to see our senior design presentation. |
| TA: Sueng-Yong Park February 14, 1998 |
Click here to see our
senior design final report. (Not yet available.) |
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 |
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 |