Thursday, June 7, 2012

Arduino Sandwhich 1: The Sea Hawk

 Each Otter Box 2500 on the bow of the Sea Hawk contains a different "Arduino Sandwhich".  An arduino uno R3 board is common to both of them, but the shields on them differ because of the different needs of the Sea Perch and Sea Hawk.  

The beauty of using Arduino Shields is that they mount piggy back onto the Arduino and the pin assignments are such that you don't lose the functionality of the Arduino board (the stackable female headers make it so that when you plug a wire into the analog or digital inputs on the top board you are effectively plugging into the same pin on the Arduino down below) and generally, for the specific function of the Shield, it is already wired to accept logic from and send logic to the Arduino. So using shields makes things very compact and plug and play.

The Sea Hawk uses 4 boards for its basic functionality. They fit inside the Otter Box 2500 and leave just enough room for wiring.

The Arduino Uno R3 is at the ground floor of the stack.  It needs its own 9 volt power supply (at the barrel plug shown in the middle top of the picture). The grey box is a USB connector for uploading the programming code (called an Arduino "sketch") to the board. You load it once  before you send the Sea Hawk out to sea...

The second layer of the "sandwhich" for the Sea Hawk is the Arduino Motor Controller, found at Radio Shack.  This requires its own 11 to 12 volt power supply to run the motors.

The next thing we put on the Sea Hawk stack is a GPS Shield.  This enables the Sea Hawk to report where it is as it carries the Sea Perch to its mission location,.

The top of the stack is an Arduino Prototyping Board with a MiniBreadboard adhered to the space between the female headers.  Note the orientation of the breadboard; you need to mount it so that the long side of the rectangle is between the headers so that you can mount the bluetooth Bluesmirf wireless chip and the Navigational compass properly (make sure that the pins of these devices are in breadboard holes that are not electrically connected!!)

The bluetooth module on top allows us to drive the Sea Hawk from our Android phones using the Amarino apk.   We need to keep the Prototyping shield with the Bluesmirf and compass on top so that we can wire them to the Arduino female headers. Unlike the motor shield and the GPS, which are internally wired through their header pins to the Arduino, the prototyping shield merely provides a pass through for the arduino pins and a breadboard; you have to wire the breadboard to the pins to get them to talk.

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