First, if the admins think this is too closely related to my "general" question in the other section, please take appropriate corrective actions.

I have a few specific programming questions so I figured I would post here for some help.

I am using a 2n2222 transistor to switch a laser circuit on/off. The first sketch I have posted worked just like I thought it would. From previous suggestions, I know the delay function is not ideal, but I wanted an obvious indicator if I could get the desired response.

I have laser1 wired to the 2n2222 base (through a resistor).

//Laser Maze Program
//Assign laser units to pins
const int laser1 = 22;

void setup()
{
pinMode(laser1, OUTPUT);
}

void loop()
{
digitalWrite(laser1, HIGH);
delay(5000);
digitalWrite(laser1, LOW);
delay(5000);

}

Feeling quite confident at this point, I then attempted to use a PB to turn the laser on and off. I am still getting my head around when an input pin is high/low, but I figured I could get the laser to turn off and on based on if I held the button down. My thinking was the laser would either be on at start up and turn off when I held the button down or it would be the other way around.

Nope! With the following sketch, the laser was always on - regardless of PB condition. I will say I was measuring the voltage at the pbeasy pin and it was measuring correctly (0V or 5V) when the PB was pressed/released.

Here is the sketch.

//Laser Maze Program
//Assign laser units to pins
const int laser1 = 22;
const int pbeasy = 51;

void setup()
{
pinMode(laser1, OUTPUT);
pinMode(pbeasy, INPUT);
}

void loop()
{
if (pbeasy == LOW)
digitalWrite(laser1, HIGH);
else
digitalWrite(laser1, LOW);

}

So, any obvious mistakes on why laser1 wouldn't play nice with pbeasy? Small disclaimer: I am about 1 week into learning how to program so go easy and talk slow.

Thanks

 

I am not an arduino programmer but I will give this a shot.

The statement:

const int laser1 = 22;

makes laser1 a constant value and will not change. Remove the const.

The words LOW and HIGH are boolean values. Usually these are defined as zero and no-zero respectively.

Hence the statement:

if (pbeasy == LOW)

is invalid because pbeasy is int while LOW is boolean.

 

I'm assuming "pbeasy = 51" represents pin 51, which is an input pin connected to your push-button. Your current code is not checking whether pin 51 is currently HIGH or LOW, it's actually checking whether "51 == LOW", which it isn't.

You need to do use the DigitalRead() function to read the current status of the pin:

[COLOR=#CC6600]if[/COLOR] (DigitalRead(pbeasy) == [COLOR=#006699]LOW[/COLOR])
...

Note that you will have some bounce when you push and release the button (the laser may very quickly flash on/off before settling into the correct state). See the Arduino tutorial on debouncing switches if you want to eliminate it.

 

const int laser1 = 22;

makes laser1 a constant value and will not change. Remove the const.

This is actually OK, 22 represents the pin# that the laser is connected to, which doesn't change.

Also, unlike more modern languages, C does let you mix booleans and integers. 0 is false while any other value is true.

 

http://arduino.cc/en/Tutorial/Button

 

I'm assuming "pbeasy = 51" represents pin 51, which is an input pin connected to your push-button. Your current code is not checking whether pin 51 is currently HIGH or LOW, it's actually checking whether "51 == LOW", which it isn't.

You need to do use the DigitalRead() function to read the current status of the pin:

[COLOR=#CC6600]if[/COLOR] (DigitalRead(pbeasy) == [COLOR=#006699]LOW[/COLOR])
...

Note that you will have some bounce when you push and release the button (the laser may very quickly flash on/off before settling into the correct state). See the Arduino tutorial on debouncing switches if you want to eliminate it.

Now I feel like an idiot. If you saw how many notes I have taken and pages I have printed (even some actual lines I hand wrote on paper), where I had the digitalRead portion correct. Then, when I go to actually write the sketch, I do it wrong!

Maybe this public embarrassment will burn this into my brain! I can only hope - but not promising.

Thanks for pointing that out!