How do I run a state machine once in an Arduino loop - arduino

Question

I am attempting to photograph water drop collisions using two solenoids. I have successfully done this using one solenoid. This used setting delays in the code to time the camera shutter, water drops and flash. I would like to trigger two solenoids at the same time with identical delays but not sure how to do this.
The order of operation should be
Open the camera shutter (camera is in bulb mode)
Drop two water drops from two solenoids at the same time.
Fire the flash
Close the camera shutter
My platform is an Atmega 2560. Here is the code I have so far,
int relayCam=A0; //pin to relay to trigger camera
int relayFlash=A7 ; //pin to relay to fire flash
int button1Read;
//button read delays (settling time)
int button1DT=250;
int button1Pin=8; //pin for 2 drop button read
int DelayCamOpen=100; //wait time to trigger camera
int DelayCamClose=1000; //wait time to close camera shutter
//Drop start
int DropStart=500; //time to start first drop
//Flash timing
int DelayFlashFire1=350;
int DelayFlashOff=50; //turn flash off
bool runOnce = false;
class Solenoid
{
int SolenoidPin;
long OnTime;
long OffTime;
int SolenoidState;
unsigned long previousMillis;
public:
Solenoid(int pin, long on, long off)
{
SolenoidPin = pin;
pinMode(SolenoidPin, OUTPUT);
OnTime = on;
OffTime = off;
SolenoidState = HIGH;
previousMillis = 0;
}
void update()
{
unsigned long currentMillis = millis();
if((SolenoidState == HIGH) && (currentMillis - previousMillis >= OnTime))
{
SolenoidState = HIGH;
previousMillis = currentMillis;
digitalWrite(SolenoidPin, SolenoidState);
}
else if ((SolenoidState == LOW) && (currentMillis - previousMillis >= OffTime))
{
SolenoidState = LOW;
previousMillis = currentMillis;
digitalWrite(SolenoidPin, SolenoidState);
}
}
};
Solenoid drop1(A1, 55, 55);
Solenoid drop2(A2, 55, 55);
void setup()
{
pinMode(relayCam, OUTPUT);
pinMode(relayFlash, OUTPUT);
pinMode(button1Pin, INPUT);
}
void loop()
{
//This part works
button1Read=digitalRead(button1Pin);
delay (button1DT);
if(button1Read==0) {
delay (DelayCamOpen); //wait time after button is pushed to start sequence
digitalWrite (relayCam,LOW); //opens the camera shutter
delay (DropStart); //wait time after shutter opens ro start first drop
//This part does not execute
if (runOnce == false)
{runOnce = true;
drop1.update();
drop2.update();
}
//This part works
delay (DelayFlashFire1); //wait time to fire flash
digitalWrite (relayFlash,LOW); //fire flash
delay (DelayFlashOff); //time to keep flash open (very short time)
digitalWrite (relayFlash,HIGH); //close flash relay
delay (DelayCamClose); //wait time to close camera shutter
digitalWrite (relayCam,HIGH); //close camera shutter
}
else if(button1Read==1)
{
digitalWrite (drop1,HIGH); //no signal to waterdrop
digitalWrite (drop2,HIGH); //no signal to waterdrop
digitalWrite (relayCam,HIGH); //no signal to camera
digitalWrite (relayFlash,HIGH); //no signal to flash
}
}
The camera and flash portion is working but the solenoids do not. I'm not sure if I'm even going about this correctly. I do know that having delays to run two solenoids is not giving me the desired results, hence trying to use the state machine method. Any help/suggestions is greatly appreciated. I am new to writing code and all things Arduino.
This is the code that works with one solenoid.
//Pin assignments
int relayCam=A0; //pin to relay to trigger camera
int relayFlash=A7 ; //pin to relay to fire flash
int relayWD1=A1; //pin to relay to trigger water drop 1
int button1Read;
//button read delays (settling time)
int button1DT=250;
int button1Pin=8; //pin for 2 drop button read
//drop sizes
int dropSize1=55; //time to hold relay for 1st drop
int dropSize2=45; //time to hold relay for 2nd drop
//delays betwween drops
int Delay1=45; //time between 1st and 2nd drops
//camera shutter timings
int DelayCamOpen=100; //wait time to trigger camera
int DelayCamClose=1000; //wait time to close camera shutter
//Drop start
int DropStart=500; //time to start first drop
//Flash timing
int DelayFlashFire1=350;
int DelayFlashOff=50; //turn flash off
void setup() {
pinMode(relayCam, OUTPUT);
pinMode(relayWD1, OUTPUT);
pinMode(relayFlash, OUTPUT);
pinMode(button1Pin, INPUT);
}
void loop() {
button1Read=digitalRead(button1Pin);
delay (button1DT);
if(button1Read==0) {
delay (DelayCamOpen); //wait time after button is pushed to start sequence
digitalWrite (relayCam,LOW); //opens the camera shutter
delay (DropStart); //wait time after shutter opens ro start first drop
digitalWrite (relayWD1,LOW); //starts first drop
delay (dropSize1); //duration of water flow
digitalWrite (relayWD1,HIGH); //stops first drop
delay (Delay1); //wait time for second drop to start
digitalWrite (relayWD1,LOW); //start of second drop
delay (dropSize2); //duration of waterflow
digitalWrite (relayWD1,HIGH); //stops second drop
delay (DelayFlashFire1); //wait time to fire flash
digitalWrite (relayFlash,LOW); //fire flash
delay (DelayFlashOff); //time to keep flash open (very short time)
digitalWrite (relayFlash,HIGH); //close flash relay
delay (DelayCamClose); //wait time to close camera shutter
digitalWrite (relayCam,HIGH); //close camera shutter
}
else if(button1Read==1)
{digitalWrite (relayWD1,HIGH); //no signal to waterdrop
digitalWrite (relayCam,HIGH); //no signal to camera
digitalWrite (relayFlash,HIGH); //no signal to flash
}
}

Answer 1

The abstraction represented by your update() method is tortured and confusing to me. My suggestion is to replace update() with two methods startDrop() and stopDrop(). startDrop() records a startTimestamp (like you've done with currentMillis but a class member variable) and opens the solenoid. stopDrop() compares the elapsed time and returns false if not enough time has passed and the solenoid remains open, or returns true if enough time has passed and the solenoid is closed.
class Solenoid
{
...
private unsigned long startTimestamp;
void startDrop()
{
startTimestamp = millis();
digitalWrite(SolenoidPin, LOW);
}
bool stopDrop()
{
if ((millis() - startTimestamp) >= OffTime)
{
digitalWrite(SolenoidPin, HIGH);
return true;
}
return false;
}
...
}
void loop()
{
...
drop1.startDrop();
drop2.startDrop();
while (drop1.stopDrop() == false);
while (drop2.stopDrop() == false);
...
}
That's just a rough draft. You might want to add some error checking to ensure that, for example, the solenoid was closed before startDrop() or that startDrop() was called before stopDrop().