Meant to be a quick recap of some mechatronic and embedded basics, I made a “Slingatron” type toy to launch ball bearings [http://www.space.com/23015-slingatron-reusable-launch-system.html].
Of course, in my infinite wisdom, I went against my nature and rushed at the end of this first phase (getting the DC motor oscillating/spinning either direction with speed control knob] and have in turn made an embarrassing mistake. I was ready to flash the FLASH and give a demo (it was running off of RAM previously, so the program would only survive as long as there was power). I hooked the battery pack up so I wouldn’t need a computer to power it. Wait, NO! The USB supply is still connected! Both power sources were flowing to the board at the same time! On top of that, my power pack is a bit over 5V. The board was expecting 2xAA batteries, not 4. Sigh…I was just so excited that I let my engineer self out the door before my kid self finished looking at the pretty lights and sounds. I blew the FTDI chip. It was the serial communication and JTAG to the device and memory. I knew the moment I did it that I shouldn’t have done that.
What to do? Keep moving forward. Okay, so I don’t get to give a show and tell yet, it’s still a fun idea. I can either buy a new CC3200 or use a different board…
I think I’ll use a different ARM M4 board since I have one available. I won’t be able to port the code within time, but it should be really straight forward. Anyway, the launch will just have to wait a little longer. Besides, I need to tweak the spinning mechanism. There’s lots more to do. Here’s some pictures:
Well, it looks pretty. A ball bearing is placed into the spiral tube, towards the center. As the spiral tube oscillates, the bearing picks up speed and is launched out the end.
Still lights up, but wont let me FLASH or aceess the JTAG. Even if ibypass the FTDI chip and use something like an I-Jet or J-Link. C’Est la via; serves me right.
The motor driver and analog speed control are still in good shape, so replacing the main control board should do the trick. I also didn’t have a large supply of resistors on hand, so the reference voltage is about 1V instead of 1.45V. I just compensated in software for that.
The idea is that I turn the knob, changing the input voltage, which the MCU then uses to set the duty cycle for the PWM signal connected to the motor driver. An increase in duty cycle results in an increase in motor speed. Neat.
Anyway, I’ll let you know what the next version looks like.