//********************************************************************
//*                                                                  *
//*                       RV-Project.Com                             *
//*                        Camera Switch                             *
//*                                                                  *
//*                        Apr-06-2018                               *
//*                                                                  *
//* Use With Hardware:                                               *
//*                        MCS-2A Rev A                              *
//*                                                                  *
//* This sketch is intended for use with "bland version" Camera      *
//* Switch boards.  This software is licensed by Creative Commons    *
//* for non-commercial use only, and must be used within that scope. *
//*                                                                  *
//* Sketch works with Atmel ATTiny85-10 and above.  ATTiny85 must be *
//* set for 8Mhz internal clocking.  If default 1Mhz internal clock  *
//* is used, time delay (on period) will not be accurate.            *
//*                                                                  *
//* This version of the camera switch is a simple latching version.  *
//* It is intended to be used with a positive going 12V trigger, as  *
//* you may find from a brake light circuit. Once triggered, the     *
//* switch stays on until it times out. The salient characteristics  *
//* of this switch are; Opto isolated input, surge suppressed input, *
//* output, and power supply line voltage, trigger can be momentary  *
//* or constant (i.e. brake light or tail light), and MOSFET switch  *
//* camera circuit.                                                  *
//*                                                                  *
//* While latching a momentary signal is obvous, what is less obvous *
//* is the ability to monitor a tail-light circut, for example; why  *
//* that is even necessary, since 12V is available all of the time   *
//* from the tail-lights. However, many tail light circuits are      *
//* overloaded, at least from a voltage drop perspective, so in this *
//* instance, the switch acts like a remote relay to ensure 12V is   *
//* applied to the camera even if the trigger (tail-light) circuit   *
//* is voltage deficient. Maintaining 12V ensures the camera  has    *
//* sufficient voltage for maximum performance and transmit range.   *
//* board has the same pim=-outs for pins 1 thru 4.                  *
//*                                                                  *
//* One might wonder why use such a sophisticated setup when a sim-  *
//* ple relay would work for a tail-light circuit. Well it would.    *
//* However, remember we have a variable delay that we can dial in,  *
//* so imagine a scenario where you pull into a rest stop, turn your *
//* vehicle off. If a sufficient delay is dialed in, the camera will *
//* stay on during the duration of the stop.                         *
//*                                                                  *
//* Or perhaps you are backing your RV in, and that includes turning *
//* the vehicle on and off a couple of times. An off delay will pre- *
//* vent the camera from shutting off and turning back on each time  *
//* you start or stop the vehicle.                                   *
//*                                                                  *
//* Of course, the primary reason for using this switch is for a     *
//* a connection to the brake light, or any other momentary trigger, *
//* such as backup lights.                                           *
//* It's simply flexible enough that it can be used for a tail-light *
//* or other constant-on circuit. But also remember this device has  *
//* voltage surge suppression to protect the camera as well.         *
//*                                                                  *
//* This is a very simple sketch and useful for a first time project *
//* for those wanting to learn the Arduino IDE.                      *
//********************************************************************
unsigned long delayValue=2;  //change to 2 (seconds) for testing.
int triggerValue = 512;
int Trigger = 0;
// hardware pin assignments
int triggerPin = 2;    //physical pin 3
int cameraPin = 3;     //physical pin 2
int delayPinA = 0;     //physical pin 7
int delayPinB = 1;     //physical pin 6
int delayPinC = 2;     //physical pin 5
//timer variables
unsigned long previousMillis = 0;       
void setup(){
pinMode(delayPinA,INPUT);  
pinMode(delayPinB,INPUT);  
pinMode(delayPinC,INPUT);  
pinMode(cameraPin,OUTPUT); 
digitalWrite(cameraPin, LOW);             //initialize with camera off.
// read the delay switches and set delayValue from 30 minutes to 3 1/2 hours in 30 minute increments.
if(digitalRead(delayPinC)==LOW) delayValue = 1800;                  // 30 minutes in seconds                 
if(digitalRead(delayPinB)==LOW) delayValue = delayValue + 3600;     // 1 hour in seconds                               
if(digitalRead(delayPinA)==LOW) delayValue = delayValue + 7200;     // 2 hours in seconds  
delayValue = delayValue * 1000;                                     // convert seconds to mS
// since the delay value is read in Setup, the ATTiny85 must be reset before any changes are 
// made. This can be done via reset pin or power cycling the board.
} //********************************* End Setup ********************************
void loop()
{
unsigned long currentMillis = millis();
Trigger = analogRead(triggerPin);    //read the trigger voltage
// Note: By default, the camera turns on when the trigger goes above 2.5V as measured at the
// output of the OptoIsolator. This is a "positive going trigger". To create a negative trigger
// i.e. triggers on ground, change the "<" on the next line to ">".
// The default value of 512 for the triggerValue should be sufficient for most purposes, but can
// be set to different values. 0 = 0V and 1023 = 5V. When setting this value, measure the voltage
// on the ATTiny85 physical pin 3 in both conditions (with input ON and input OFF). Once you
// have the ON and OFF voltage threshold, set the sensitivity midway between the two voltages.
// Calculate the threshold number by "thresholdset / .00048"; which maps 0-5V to the ADC output of 0-1023 
   if(Trigger < triggerValue)            //set the sensitivity
   {
      digitalWrite(cameraPin,HIGH);
      previousMillis = currentMillis; 
      delay(500);                       //delay prevents debouncing.
   }
  if(currentMillis - previousMillis > delayValue)           //if the delay timer exceeds the last trigger event...
  {
    digitalWrite(cameraPin,LOW);                            //turn the output MOSFET off.
  }
} //********************************* End Loop ********************************