DrawBot – Halp!!! No – seriously, a little help?

Okay, I’m stuck.  I don’ t know what I’m doing wrong or what I need to do next.  So, I’m calling upon John Abella, Sandy Noble, and Kongorilla for your help.  :)

Here’s where I am:

  • The burning!
    • At last attempt, I hooked up some small steppers to the Adafruit motor shield, put the shield on my Arduino Uno, hooked up the USB cable and the 9v power adapter.
    • I heard a small pop and smelled warm electronics.1
  • After the burning
    • I can upload and run the Arduino basic blink sketch.  I can alter this to change the blinking pattern.
    • I can upload and run the Arduino sketches to operate a microservo.  I can alter this to change the microservo’s behavior.
    • I can upload the Adafruit sketches for steppers – but I can’t make the steppers move.
    • I can upload the Polargraph sketch – but I can’t make the steppers do anything.

Now, I’ve got tons of questions for you:

  1. Did I ruin my Arduino?  I can still run the blink and microservo sketches.
  2. Did I ruin my motor shield?  How can I tell if it is operational?  When I connect the power to the Arduino and have the little jumper in place, the green LED is lit up.
  3. What am I doing wrong?
  4. What should I try next?
  5. How should I diagnose a problem?

  1. Now I’ve got a cold and couldn’t smell anything if I wanted []

2 Responses to “DrawBot – Halp!!! No – seriously, a little help?”

  1. whosawhatsis says:

    Sounds like you fried a chip on the shield. It’s probably the L293D motor drivers, perhaps your motors draw too much current? You can replace them with pin-compatible SN754410 ICs that can handle more current, or you can use piggybacked pairs of L293Ds for to split the current draw. Heatsinks couldn’t hurt either.

    Did you calculate the current draw for your stepper motors based on voltage and phase resistance to make sure the driver ICs could handle the current?

  2. kongorilla says:

    1+ for what whosawhatsis said, but looking at the motors you got, current should be fine for the L293Ds that are stock.

    To be clear, (and to refresh my memory how things should be set up, smart people please correct me), on the shield, you had the power jumper off when this happened, so the arduino was powered by usb, and the 9v adapter was wired to the shield. And, very importantly, you had the polarity of the the adapter connection correct? (You knew which wire was positive and which negative and attached them to the shield appropriately?)

    You had the ICs oriented correctly in their sockets (notch up, dot down)?

    You checked (with a magnifying glass) for any shorts that could easily happen when soldering the sockets to the shield?

    That’s all I can think of now, without seeing what you’ve got.

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