serial monitor locks after exceeding threshold

Q # 1: How do you have the photocell wired to the analog pin?   Like this?

Q # 2: What does it do if you shine a bright light on it?

#1 - The photocells are wired with a 10k pulldown resistor. They seem to

pass the correct data, so long as the values are less than the threshold,

but I assume this isn't the fault of the sensors but rather some glitch in

the code.

#2 - A bright light far exceeds the 900 threshold and will lock in

immediately at just over 900, displaying nothing further. Then, when in

darkness, no further data appears.

It could be that an additional delay(500); is needed

just before the sketch attempts change direction of the stepper.

while (digitalRead(leftSwitchPin) == LOW) //keep going until limit switch reached

Should have mentioned that another sketch, including similar analog input, will display values as intended without a problem. Seems the sketch in question doesn't like the "while" code?

Saying the LDR is wired with a pull down resistor does not give me the level of detail I expected.  Where is A0 and +5 V connected, eh?

Back in the old days before integrated ADC the LDR would be used in this fashion.  http://www.rentron.com/micro-bot/images/CDS_Circuit.gif

The discussion about that style of implementation is found here: http://www.rentron.com/micro-bot/cds.htm .

Happy Trails

Have you tried changing the while statements to if statements?

I would add a serial.println within the while loops, like this:

(digitalRead(rightSwitchPin) == LOW) //keep going until limit switch reached

    {

      Serial.println("rightSwitchPin is low");

      stepper1.step(-1);  //move right

    }

    while (digitalRead(leftSwitchPin) == LOW) //keep going until limit switch reached

    {

      Serial.println("leftSwitchPin is low");

      stepper1.step(1);  //move left    

    }

I'm guessing that it's getting stuck in one of those loops.

Cheers,

-Nico

I just tested this sketch. By adding the "Serial.println" within each

"while" statement, the stepper is working fine. I always appreciate your

help!

#include <Stepper.h>

#define STEPS1 200

#define STOP 0

int rightSwitchPin =7;

int leftSwitchPin =8;

int sonarPin = A0;

int sonarValue=0;

Stepper stepper1(STEPS1, 3,5,4,6);//bipolar

void setup()

{

  stepper1.setSpeed(30);

  Serial.begin(9600);

}

void loop()

{

  sonarValue = analogRead (sonarPin);

  Serial.println (sonarValue);

  if (sonarValue >900)

  {

    while (digitalRead(rightSwitchPin) == LOW) //keep going until limit

switch reached

    {

      stepper1.step(-1);  //move right

      Serial.println (sonarValue);

    }

    while (digitalRead(leftSwitchPin) == LOW) //keep going until limit

switch reached

    {

      stepper1.step(1);  //move left

      Serial.println (sonarValue);

      {

      }

    }

  }

Yes! I added the "println" under the while, but it works just the same.

Thanks so much.

Keith

I just looked at the details of Stepper.step, and it looks like this block is not needed (taking 0 steps should do nothing)...

  else

  {

    stepper1.step (STOP);

  }

Maybe remove that block, in case that's causing the issue?

ps, from the code it looks like when sonarValue goes over 900, the stepper motor will go all the way right until the limit switch is hit, and then it will go all the way left until the limit switch is hit, and then it reads the sensor again, waits half a second, and repeats the process. Was that the intention?