|68HC11 Slave I/O|
I moved to Alaska, in November of 1996, I decided I needed something to
keep me occupied during the long, dark winter. Since I had a fair background
in electronics and pretty good computer skills, and I am a mechanical engineer
specializing in petroleum automation, robotics seemed like a good choice.
I purchased "Mobile Robots ..." by Jones and Flynn and away I went. By spring of 1997 I had built from scratch a very basic robot. Always being one to do it my way (= the hard way), I tore my hair out trying to get that poor 68HC11 to do what I wanted.
By spring 1998 I managed to get encoders and I/R detectors working and was getting pretty comfortable with the microcontrollers. I wrote a packet controller for R/F radio modules that works very well giving me live remote data from the robot. I had a robot that could actually travel in a straight line. My wife was very impressed :). My poor robot was suffering from way too much rework and it was too small for my bad eyes, so, in summer of 1998, I started a new one. This ones a foot in diameter and designed by someone who actually had a clue what they were doing - I've come a long way in 3 years.
I decided to convert over to the 68HC12 and to move to Imagecraft C language. I have done some collaboration with other robot folks and got into networking multiple microcontrollers. I've noticed that I have a fetish for getting computers to talk. My 68HC11 Slave I/O project was born from that.
My robot can almost navigate its way around our house. I plan on adding a Dinsmore compass next to help that along. Object avoidance is working well. I'm especially proud of my stairs detection - this was a big problem because it could wander aimlessly for hours until it tried to go down the stairs. A Sharp GP2D12 analog distance sensor works very well aimed at a 45 deg angle down in front.
When I think about what I've learned over the last few years it's mindboggling. I can design and hook up CMOS circuits, switching power supplies, RF radios, SPI networks, memory chips, RS-232 circuits, DC motor controls, current sensors, I/R encoders, audio in and out, Sonar modules, I/R distance sensors, batteries and many things I 've forgotten about. I can use breadboards or wire-wrap a circuit together. I never go far without my trusty EBay oscilloscope. I understand microcontrollers and can put them to use. I built a 4 channel Christmas light controller last fall. I learned SBasic, then Visual Basic, then assembler, then C and now I'm working on C++ and Real Time Operating Systems. I've specified DC motors, pulleys, belts and axles. I've studied and put to work navigation techniques.
I'm glad to see Robotics becoming a bigger part of the education world because they are an ideal educational platform.
My robot now navigates around the house, avoids objects by I/R and stall current, hums a song that changes with its mode, feeds back data to my PC, monitors its own battery level and ambient light level, knows distance to objects from 6" to 25' away. And this is just the beginning. Have you seen those new Sony Vaio laptops - those would fit in my robot - Hmm.
It still doesn't impress my wife, though. Need to get him to vacuum.
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