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Rocco – Circuit and Arduino

Servo Power Supply

I had a left over power supply with a molex connector on the end that can put out 5V @ 2A or 12V @ 2A.  I am using it at 5V to independently power the servos collectively.  I also re-purposed a female molex to 2-pin adapter to get the power to the breadboard.

I am not sure yet how much current these servos draw.  I only know that 2A is enough because, well, I tried it.  I tried to measure this with my multimeter but could not get a valid reading.  I later discovered most multimeters can’t read servo current.

Below are two possible explanations (they may be the same) and a discussion about idle and stalled current draw:
http://forum.arduino.cc/index.php?topic=109988.0
http://www.rcuniverse.com/forum/rc-radios-transmitters-receivers-servos-gyros-157/2357551-how-much-power-does-servo-use.html

I will find a way to measure before adding more servos or planning a battery system.

Circuit

I ordered a SunFounder breadboard kit with jumper wires and some other components for testing.

SunFounder Kit:
http://www.amazon.com/dp/B00DGNZ9G8/ref=pe_385040_121528360_TE_dp_1

I haven’t made a schematic yet for how I have the board and servos wired up.  I would like to make one in Fritzing but for now, here are some photos:

I’m using the potentiometer from the SunFounder kit to increase/decrease an interval value in the code.  I’m also using a switch from the kit to enable/disable an HC-06 Bluetooth module.

Bluetooth serial module:
http://www.amazon.com/dp/B0093XAV4U/ref=pe_385040_127541860_TE_dp_1

Fritzing circuit design tool:
http://fritzing.org/home/

Lastly, I am using some servo extension cables to give myself some room to work.

Futaba / JR Style Servo Extension Leads:
http://www.amazon.com/dp/B00DU7KLCM/ref=pe_385040_30332200_TE_item

Arduino

I chose an Arduino Mega 2560 R3 for the main board.  I’ve never used an Arduino before so this is exciting.  There are dedicated products for controlling servos and pre-programming motions, but I’m currently putting an emphasis on coding as much of this project as possible.  The Mega has enough pins to control (but not power) all 18 servos.  I’ve read there may be problems with interrupts or “bandwidth” when trying to control all 18, but I’m still going to try.  If it doesn’t work out I’ll look at adding hardware to the project.

I like this board:
https://www.pololu.com/product/207

This one I feel is cheating:
https://www.pololu.com/product/1350

The Arduino can be powered with a wide range of supplies, but I am using a generic 9V DC 650mA supply from Amazon.

Arduino Safety

Knowing nothing specific about Arduino boards or dev boards in general, I looked up what kinds of things can break it (so that I don’t do those things).

10 Ways to Destroy an Arduino:
http://www.ruggedcircuits.com/10-ways-to-destroy-an-arduino/

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