Controller Electrical Design

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E128 Pinout

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Joystick

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The joystick has the ability to control 2 degrees of freedom and has two momentary push button switches (although only one button is used).  The wiring inside the joystick was modified to fit our needs.  One pot is dedicated to each axis of rotation. The output voltage from the potentiometers varies as the user rotates the joystick.  Trim pots on the joystick allow fine-tuning of the controls on the fly without have to change software. 

Servos

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Two servos are used on the controller: one for indicating crab pot ID and one for crab accumulation rate.  It was designed such that the power to the servos could be turned off when not in use in an effort to save power; although, we ended up not using this functionality.   The signal to the servos is a PWM signal from the E128.  By changing the duty cycle of this PWM signal, the position of the servo can be changed.  

Power 

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We have three batteries powering our controller and three power regulation circuits shown to the left.  One for the E128 and logic level signals and one for each servo dial indicator.  We could have used two batteries, but it would not have made the 8 hour continual use requirement. 

LEDs

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Three LEDs are housed on the main module of the controller.  They are used to indicate when the system is ON, when the controller has received the fleet cipher, and when Neptune says Game On. 

Power Calculations

We are using a total of three 1400mAh 7.2V NiCd batteries for our HC. One battery is used for the E128 and the logic circuits, and one for each Servo. The E128 battery draws about 70mA current when all sensors  and LEDs are active. This translates to about 20 hours running time.  Each servo draws about 150mA current when active and that makes those batteries last for 9 hours and 20 minutes which exceeds the 8 hours running time requirement.