Arduino Schematic HELP!

[skillz21]

Hey, guys!
I am trying to build a... thing ( ) that tracks motion and turns on some led lights when I step off my bed. I will be using two HC-SR04 ping sensors to track both sides of my bed. a problem that I am currently having is, I need to make a variable continually count down every second, and to stop when it reaches around -10. I want the LEDs to light up when the variable is above 0. how do I make the variable stop once it reaches -10? If you need more info, please ask

Thanks

BTW: I have had some issues on the forum when I wanted to get straight answers and people were trying to teach me C#. Guys, I'm doing that at the moment. I'm still only 12.

[skillz21]

Also, how do I make the value count down 1 every second?

[JPortici]

BTW: I have had some issues on the forum when I wanted to get straight answers and people were trying to teach me C#. Guys, I'm doing that at the moment. I'm still only 12.

what else should have they done?

the logic is pretty straightforward
- you have a variable that should be updated every second
- if the variable value is greater than zero then switch on the leds
- otherwise (else), if the variable value is lower than ten then switch off the leds and stop counting
it's pretty basic [insert language name], nobody will seriously bother telling you because if you can't do/learn that on your own it probably means that you don't care (worst scenario) or you can't undestand what's going on anyway (best scenario)

note that the worst case was put first, for a very good reason. in case you genuinely don't know the language you must learn it before so you can understand what you are being answered

then you need to generate an event every second or to wait idling for a second, there are lots of ways to do that. for the second one you usually have ready made functions

[madires]

For the 1s timer: http://playground.arduino.cc/Code/Timer1

[skillz21]

wait, are you saying that I don't care about learning c#? I do, very much. please don't get the wrong impression just because I'm a kid

[skillz21]

For the 1s timer: http://playground.arduino.cc/Code/Timer1

Is it possible to do it just with a variable and not with a timer and a dedicted library.

[skillz21]

Here is the sketch that I made. please correct me in any place that I am wrong. also, the time reset is now a pushbutton, setting the value to 5. This sketch does not work.

int timeVal = 0;
void setup() {
  pinMode(8, OUTPUT);
  pinMode(A0, INPUT);
}

void loop() {
timeval - 1
if(timeVal > 0){
  digitalWrite(8, HIGH);
  }
else{
  digitalWrite(8, LOW);
  }
if(A0, HIGH){
  timeVal = 5;
  }
}

Also, I have gained most of my knowledge of C# from Scratch. I am trying to use the same... components of the programming, if that makes any sense.

[madires]

Is it possible to do it just with a variable and not with a timer and a dedicted library.

Using a timer for such things is a standard solution. Either you use an interrupt (with an interrupt handler) or have to check for the timer flag regularly. The library is convenient, but you can do it also directly. I'm sure you'll find a lot of examples when searching the internet.

[skillz21]

Is it possible to do it just with a variable and not with a timer and a dedicted library.

Using a timer for such things is a standard solution. Either you use an interrupt (with an interrupt handler) or have to check for the timer flag regularly. The library is convenient, but you can do it also directly. I'm sure you'll find a lot of examples when searching the internet.

ok

[Ammar]

Happy to give you some hints.

You can use the millis() function to find the time in ms since power on in milliseconds. Something like:

timeNew = millis();

See if you can use your loop and some if statements with the millis() function to solve your problem.

You could use a while loop with the condition you outlined to make the variable stop when you want. I hope that helps and good luck!

[Psi]

I dunno if this will compile, but ive tried to do what you want using the millis function.


int TimeVal = 0;
unsigned long PreviousMS = 0;
unsigned long CurrentMS = 0;

void setup() {
  pinMode(8, OUTPUT);
  pinMode(A0, INPUT);
}

void loop()
{
    // loop runs VERY fast, we need to run some code slower to do the subtraction at 1 second.
    // Arduino has a millis() function to read the number off milliseconds
    // since the arduino started running.
    // We can store this number and then wait for the current time to equal the prev time plus 1000ms
    // then update the previous time to current time and let it repeat forever. This lets us run some code once a second.
   
    // get current time
    CurrentMS = millis();

    // if more than 1000 ms have past since previous time, do stuff.   
    if ( CurrentMS > (PreviousMS + 1000))
    {
         // code inside here happens once a second (1000ms)

         // only count down if value is larger than -10, once it reaches -10 it stops count and stays at -10
         if (TimeVal > -10)
         {
              TimeVal = TimeVal - 1;
         }

         // last thing we do is update our previous time variable to the current time
         // so the process can repeat again in another 1000ms.
         PreviousMS = CurrentMS;
    }



    // this is outside of our 1 second if statement, so it repeats very fast.
    // which is ok for setting leds on or checking inputs.

    if (TimeVal > 0)
    {
         digitalWrite(8, HIGH);
    } else {
         digitalWrite(8, LOW);
    }

    if (digitalRead(A0) == HIGH)
    {
         TimeVal = 5;
    }
}

[madires]

If you're using millis() you should read https://www.arduino.cc/en/Reference/Millis , especially:

Returns the number of milliseconds since the Arduino board began running the current program. This number will overflow (go back to zero), after approximately 50 days.

So you need to add an overflow detection.

[Ian.M]

Why would you want to learn C#?
That's one of Microsoft's .NET managed abominations and has *NOTHING* to do with writing Arduino code.

The Arduino 'programming language' is merely a very thin wrapper around GNU C++. 
See http://hackaday.com/2015/07/28/embed-with-elliot-there-is-no-arduino-language/ for the details.

[zapta]

The Arduino 'programming language' is merely a very thin wrapper around GNU C++. 
See [

The Arduino programming language *is* C++.

They just don't tell you that. It's a conspiracy to trick the population into learning embedded C++ programming.

[stj]

Hey, guys!
I am trying to build a... thing ( ) that tracks motion and turns on some led lights when I step off my bed.

a pressure-mat or a pir sensor would do that!

[alsetalokin4017]

Here is the sketch that I made. please correct me in any place that I am wrong. also, the time reset is now a pushbutton, setting the value to 5. This sketch does not work.

int timeVal = 0;
void setup() {
  pinMode(8, OUTPUT);
  pinMode(A0, INPUT);
}

void loop() {
timeval - 1
if(timeVal > 0){
  digitalWrite(8, HIGH);
  }
else{
  digitalWrite(8, LOW);
  }
if(A0, HIGH){
  timeVal = 5;
  }
}

Also, I have gained most of my knowledge of C# from Scratch. I am trying to use the same... components of the programming, if that makes any sense.

Your code doesn't compile because of the errors in the lines I have bolded up above.

1. You have not initialized the variable "timeval".... you obviously mean to use "timeVal" but the compiler can't read your mind like I can     . C++ variable names are case sensitive.
2. You did not terminate that line with a semicolon.
3. You have to explicitly read the A0 pin and use the conditional test == to compare to a value.
4. You need to tell it what to do if the conditional test fails (if A0 is LOW): include an else statement to reset timeVal.

So if you replace your line
timeval -1
with the line
timeVal -1;
or
timeVal --;

and the line
if(A0, HIGH){
with the line
if(digitalRead(A0)==HIGH){

and add the else statement
else timeVal=0;
after the final "if" statement

your sketch should compile and run.

But will it do what you intend?  I think you will need to insert some delay() or test for some millis() values as Psi suggests. (His suggested pseudocode makes the same error about the capital V in timeVal though.)

If you don't intend to stay in bed for more than 50 days, I wouldn't worry about overflowing the millis() timer.   

[skillz21]

Why would you want to learn C#?
That's one of Microsoft's .NET managed abominations and has *NOTHING* to do with writing Arduino code.

The Arduino 'programming language' is merely a very thin wrapper around GNU C++. 
See http://hackaday.com/2015/07/28/embed-with-elliot-there-is-no-arduino-language/ for the details.

So what is the most similar programming language to Arduino?

[skillz21]

I dunno if this will compile, but ive tried to do what you want using the millis function.


int timeVal = 0;
unsigned long PreviousMS = 0;
unsigned long CurrentMS = 0;

void setup() {
  pinMode(8, OUTPUT);
  pinMode(A0, INPUT);
}

void loop()
{
    // loop runs VERY fast, we need to run some code slower to do the subtraction at 1 second.
    // Arduino has a millis() function to read the number off milliseconds
    // since the arduino started running.
    // We can store this number and then wait for the current time to equal the prev time plus 1000ms
    // then update the previous time to current time and let it repeat forever. This lets us run some code once a second.
   
    // get current time
    CurrentMS = millis();

    // if more than 1000 ms have past since previous time, do stuff.   
    if ( CurrentMS > (PreviousMS + 1000))
    {
         // code inside here happens once a second (1000ms)

         // only count down if value is larger than -10, once it reaches -10 it stops count and stays at -10
         if (timeval > -10)
         {
              timeval = timeval - 1;
         }

         // last thing we do is update our previous time variable to the current time
         // so the process can repeat again in another 1000ms.
         PreviousMS = CurrentMS;
    }



    // this is outside of our 1 second if statement, so it repeats very fast.
    // which is ok for setting leds on or checking inputs.

    if (timeVal > 0)
    {
         digitalWrite(8, HIGH);
    } else {
         digitalWrite(8, LOW);
    }

    if (digitalRead(A0) == HIGH)
    {
         timeVal = 5;
    }
}

Is it possible to make different loops? with different speeds?

[skillz21]

Hey, guys!
I am trying to build a... thing ( ) that tracks motion and turns on some led lights when I step off my bed.

a pressure-mat or a pir sensor would do that!

Thats true, but wouldn't that be more expensive?

[skillz21]

If you're using millis() you should read https://www.arduino.cc/en/Reference/Millis , especially:

Returns the number of milliseconds since the Arduino board began running the current program. This number will overflow (go back to zero), after approximately 50 days.

So you need to add an overflow detection.

wait... so can I change the value of millis?

[stj]

Hey, guys!
I am trying to build a... thing ( ) that tracks motion and turns on some led lights when I step off my bed.

a pressure-mat or a pir sensor would do that!

Thats true, but wouldn't that be more expensive?

pir sensors cost a couple of $ on ebay.
http://www.ebay.co.uk/itm/321614189142

[skillz21]

how would i use millis in a sketch like this:

const int Button = A0;
const int Light = 8;

int timeVal = 0;
int buttonstate = 0;

void setup() {
  pinMode(Light, OUTPUT);
  pinMode(Button, INPUT);
}

void loop() {
  buttonstate = digitalRead(Button);

if(timeVal > 0){
  digitalWrite(Light, HIGH);
  }
else{
  digitalWrite(Light, LOW);
  }
if(buttonstate == HIGH){
  timeVal = 5;
  }
}

[skillz21]

Hey, guys!
I am trying to build a... thing ( ) that tracks motion and turns on some led lights when I step off my bed.

a pressure-mat or a pir sensor would do that!

Thats true, but wouldn't that be more expensive?

Ok, I should have done a bit more research before i bought the two ping sensors. Also, I bought the ping sensors so if this project doesn't work, I could use the sensors for something like a... robot. Thanks for the suggestion though! 

pir sensors cost a couple of $ on ebay.
http://www.ebay.co.uk/itm/321614189142

[alsetalokin4017]

Why would you want to learn C#?
That's one of Microsoft's .NET managed abominations and has *NOTHING* to do with writing Arduino code.

The Arduino 'programming language' is merely a very thin wrapper around GNU C++. 
See http://hackaday.com/2015/07/28/embed-with-elliot-there-is-no-arduino-language/ for the details.

So what is the most similar programming language to Arduino?

c++

[alsetalokin4017]

Is it possible to make different loops? with different speeds?

Yes, using interrupts, but we aren't quite ready for that yet.