I'm wondering if someone could have a look at my code and let me know if there's something wrong with it. I had the code done for me a while back and did a quick test and it seemed to work. I have now built a pneumatic machine for it to work on, and it's doing some strange things.

The first relay turns on and off a pneumatic solenoid, this is connected to a small pneumatic cylinder, it moves in and out. This cylinder causes a pneumatic feeder to activate and move back and forth also.

The feeder has a proximity sensor attached which lights up when the feeder is in its resting position.

The solenoid turns on for approx half a second and then back off again, this pushes the small cylinder out then back in. This sends the feeder forward, it then turns around and comes back toward its resting position. The Arduino waits for the signal from the proximity sensor to tell it that the feeder is back in its resting position before doing it again.

It then repeats this sub cycle about 20 times.

After 20 sub cycles, the Arduino turns on the second relay for about a second, before turning it back off again.

It then does this whole complete cycle 20 times before stopping.

There's a momentary switch as well, which when pushed, is supposed to restart everything again.

It almost works, the closest i have had is where it was doing the cycles but counting them wrong. i changed the subcycle to 16 instead of 20 and it would count somewhere between 10 and 16. it seems to count different each time.

I just bought a new board and tried again, but now it counts to about five subcycles and then jumps the gun and doesn't wait for the signal from the proximity sensor before doing the next sub cycle. So once again the count ends up wrong.

Any ideas what I could try?

int Relay_1 = 10;           //first Relay
int Relay_2 = 11;           //second Relay
int Prox_Input = 12;        //input signal from proximity sensor
int Switch_Input = 13;      //the switch

int Cycle_Number = 20;      //number of repeating number of "complete" cycle
int Sub_Cycle_Number = 20;  //number of repeating number of "sub" cycle
int Delay_Cycle = 1000;     //delay of the "Complete" Cycle in milleseconds
int Delay_Sub_Cycle = 500;  //delay of the "Sub" Cycle  in milliseconds

bool Button_Pushed = true ; //the state required for the button
int i, j;

void setup() {
  /*configurate the output relays to be begin "low"*/
  pinMode(Relay_1 , OUTPUT);
  digitalWrite(Relay_1, LOW);

  pinMode(Relay_2 , OUTPUT);
  digitalWrite(Relay_2 , LOW);
  /*configurate the input switch and sensor*/
  pinMode(Prox_Input , INPUT);
  pinMode(Switch_Input , INPUT_PULLUP);
  /*configurate Serial port if you want it*/

void loop() {
  if (Check_Button() == Button_Pushed) { //check the button
    for (i = 1 ; i <= Cycle_Number ; i++) { //the loop of the "complete" Cycle
      for (j = 1 ; j <= Sub_Cycle_Number ; j++) { //the loop of the "sub" Cycle
        digitalWrite(Relay_1 , HIGH);
        digitalWrite(Relay_1 , LOW);
        while (digitalRead(Prox_Input) == HIGH) {} // waiting the sensor signal
      digitalWrite(Relay_2 , HIGH);
      digitalWrite(Relay_2 , LOW);

bool Check_Button()  {
  int Reading_1;
  int Reading_2;

  Reading_1 = digitalRead(Switch_Input);
  Reading_2 = digitalRead(Switch_Input);
  if ((Reading_1 == 1) && (Reading_2 == 1))
    return true;
    return false;

enter image description here

  • please be specific about the problem. try adding some delay in your sub cycle loop.
    – Vaibhav
    Apr 7, 2019 at 7:45
  • 6V isn’t really enough to put on that barrel jack. You really need at least 7.5V because of the voltage drop across the regulator. If you want to use 6V battery then get a switching regulator to make 5V and feed it into the 5V pin instead.
    – Delta_G
    Sep 28, 2020 at 16:49

2 Answers 2


The only reason it might "jump the gun" would be this line:

         while(digitalRead(Prox_Input) == HIGH){}          // waiting the sensor signal 

I suggest you check for a transition, that is, make sure the proximity switch has become LOW, and then wait for it to become HIGH again. So for example, if sending HIGH to the relay should make the proximity sensor read LOW, then put a loop in to make sure it does that, before proceeding.


Your fuzzy picture is missing a lot of critical information that would normally be on a schematic. Links to technical information on all the hardware devices would help, azon links are normally sales info and are useless for technical information. I agree with using Vin because of the extra filtering but you need to supply it with at 7.5 or more volts as mentioned by Delta_G If I were to take a SWAG you either have input bounce and/or power supply instability and or failure.

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