As part of the newest generation of BOBs boards, two buttons, and possibly (if I have enough pins left over) a few DIP switches. As a result, there has to be code to use these buttons and put them to work. This is where my new development board comes in. Continue reading Development
My first etching tutorial was both my first tutorial, and also a tutorial in a subject that was fairly new to me at the time. In other words, it sucked. Big time.
This time I’m going to try to do it right, and have photos to prove it, So lets get started. Today I’m going to teach you, or make a feeble attempt at teaching, how to etch a board, from start to finish.
The Sparkfun Autonomous Vehicle Competition is TODAY! Continue reading AVC ’10
Half the time, something works, the other half of the time it doesn’t, and the other half of the time, it just goes up in smoke. As such was the case with my V1.5 Rev. 1 quad motor controller. Continue reading BOB update
So I finally got around to fixing a few things, and cleaning the board up, here is BOB’s newest working version of his motor controller board. Continue reading Revision 2 of Quad Low-side “Taco”
So I finally got around to getting a board designed for Generation 3 electronics, but like everything else, being the first prototype board there were some things left out and other mistakes.
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Also the Code has been updated, please check it out at: http://github.com/JoshAshby/Robotbob/tree/experimental
After several hours of research going deeper into the motor controller designs that my current Generation 3 electronics is based off of, I have finally found a few things that i can add for safety to my design, and a few suggestions to try in order to get the design working. First thing that I saw suggested a few times was adding a cap across the power lines, and while this is something I normally do, I forwent installing them this time for simplicity of the design, so I added a 1000uF 50V cap, and have a 10uF ready to go if needed. this cap is for voltage drops when the motor first kicks in.
Second thing I saw suggested a few times also was the use of a 12V zener diode between GND and the output line of the TC4424CPA mosfet driver. this diode is for power spikes, only allowing 12V or less to exist on the output line.
Finally someone suggested that the mosfet driver was burning out because it was being forced to drive a failed mosfet, so I stuck a brand new mosfet into the system, and BOOM it works perfectly, no over heating of anything, and no magic smoke went along with perfect results, now all that is left is a PWM ramp up, and ramp down test since this is a motor controller we’re talking about.
Good news for BOB
I ordered a few MOSFET drivers, and extra MOSFETs for BOB to test out and hopefully solve the problem of having no control over the motor controllers right now. The MOSFETs are still the same old IRF540N’s and the drivers are the dual 3 Amp TC4424CPA drivers. Continue reading Generation 3 Electronics
During my lunch periods I’ve started writing a technical paper on BOB, which goes into detail about his systems and build. You can see a preview of it here, Project: BOB.
I’m currently working on fixing the bug on BOB’s motor controllers that I found the other month. No matter what, the MOSFETs will not turn completely off, even when their gates are pulled low, and as a result as soon as BOB has power, his motors go crazy, to put it simply. I’ve stopped development on almost all of my projects right now because FIRST has started up again this year, and the Sparkfun AVC for 2010 is coming up in a few months which BOB has to be running for. Between these two robots I don’t have much time for other projects and so as a result don’t expect to see any new code content on this blog for a few months.