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// Watch to assure the water level swings above and below 2.5 volts every so often

// Code From: Controlling a servo position using a potentiometer (variable resistor)

// by Michal Rinott <http://people.interaction-ivrea.it/m.rinott>

#include <Servo.h>

Servo myservo; // create servo object to control a servo

unsigned long time; //Initialize HiVolts, HighTime, LowVolts, LowTime,

int potpin = 0; // analog pin used to connect the potentiometer

int val; // variable to read the value from the analog pin VoltIn

void setup(){

myservo.attach(9); // attaches the servo on pin 9 to the servo object

Serial.begin(9600); //Open a Serial Port

}

void loop(){ //start a loop

Serial.print(“Time: “); //Test Print Current time

time = millis();

Serial.println(time); //prints time since program started

VoltIn = analogRead(potpin); //input voltage (value between 0 and 1023)

VoltIn = map(val, 0, 1023, 0, 179); // scale it to use it with the servo (0 and 180)

myservo.write(val); // sets the servo position according to the scaled value

delay(15); // waits for the servo to get there

if VoltIn > HiVolts //if voltage is higher than old high, and higher than 2.6

if VoltIn > 2.6

HiVolts = VoltIn // set HiVolts to voltage

HighTime = time // set HighTime to now,

LowVolts = 2.5 // set LowVolts to 2.5

if VoltIn < LoVolts //if voltage is lower than old low, and lower than 2.4

if VoltIn < 2.4

LoVolts = VoltIn // set LowVolts, to voltage

LoTime = time // set LowTime to now

LowVolts = 2.5 // set HiVolts to 2.5

if abs(LoTime – HiTime) > 10000 //if ABS(LowTime – HighTime) is too long

Serial.print(“Time of failure: “); //send error

Serial.println(time);

delay(2000); // wait so as not to send massive amounts of data

} //end loop

Robot Base from Hobby King

L293D power drive chip 

Here is the link to a good lm293 guide

http://m.instructables.com/id/Control-your-motors-with-L293D-and-Arduino/step3/Arduino-code/ 

with a larger blow up of the L293D on a prototype board

Shipping for HC05 Modules  EBAY tracking

http://vod.ebay.com/vod/FetchOrderDetails?ViewPaymentStatus&transId=1224051213018&itemid=281348747108

Shipping for Arduinos  ada fruit order    530186-5768100666

Here is a simple front/back, left right robot control on instructable 

http://www.instructables.com/id/Control-DC-Motors-with-your-Smartphone-Perfect-for/

___________________________________

I the site we used to wire the motors is

Instructables

http://m.instructables.com/id/Control-DC-Motors-with-your-Smartphone-Perfect-for/

The simplest android phone software is at tech bitar.

He has a very simple interface that toggles any pin on the arduino high and low.

http://www.techbitar.com/ardudroid-simple-bluetooth-control-for-arduino-and-android.html

John David was able to get his bot rolling using that combination.

The final puzzle piece is MIT App Inventor.  That would facilitate a real controller interface on the phone.

I would love to do a Saturday follow-up this fall.

By the way.  The motors are wired in series to slow the robot down.  I think that was a mistake.  I think they should be wired parallel to allow full battery voltage to drive each motor.

Jenny is setting up a saturday, so if you are interested please get in touch with her.

Good luck and keep in touch

nice write up of a HS robotics class

http://makezine.com/2015/01/05/losing-to-my-high-school-class-a-big-win/

Airgas San antonio

Intro to Electronics

Robot Kit:

pololuReversingRobot.pdf

Instructions:

sound_reversing_car (1)