I’ve been meaning for ages to get my turtle* project back up and running, and having put the quad siblings to bed for a while, I’ve finally had time.
By using a B+, I finally have enough GPIO pins to drive the stepper motors directly via 8 pins and mosfets rather than using the 74HC595 serial to parallel latch. That’s simplified the circuitry and software a lot. I’ve also turned the turtle into a WAP. Finally, I’ve swapped batteries from unregulated 2S LiPo to a 2.4A phone charger bank. This gives just about enough power – the 2.1V battery bank shown in the picture didn’t work – the motors drew enough current to trigger a safety switch in the battery.
I’m hoping to do a tutorial at the next Cotswold Jam, starting at a flashing LED and ending in a robot in 10 easy steps. In the meantime, just watch her boogie!
P.S. For a giggle, watch the original “Yes Sir, I can boobie” on youtube.
*A turtle should really have a pen controlled by a solenoid to leave a trail as it wanders. A more useful implementation for the modern era would be as the base for a laser cutter, or 3D printer: consider attaching the stepper motors to a fixed base at 90° to each other independently manoeuvring a suspended platform around underneath a fixed position laser or molten plastic feeder? It’s only a different LEGO layout from what the turtles doing now.
In fact, my next project, piPlotter, has just been conceived, using the turtle motors to move a Raspberry Pi 7″ touch screen running a draw application with a stylus touching the screen to draw out the movement. More of a LEGO project than a RPi project, and a lot more fun as a result. Oh, and cheap too!