Turning on the LED after a while.

Question

Hello everyone.

The task:

Use the button to turn on and off the LED after a while.

For example, we pressed a button - the LED turned on and went out after 10 seconds. And so it should turn itself on every 5 minutes for 10 seconds. Then, press the button and the LED stops working and until the next button press, it does not work.

What features are better to use? Or who has a similar example?

ankur608 · Accepted Answer

Don't use void loop() func. twice as suggested by Shabaz, and the token error is usually due to wrong closure of {\}. Define the blink sequence under (regim==1) while maintaining the 'flag' logic. Hence, avoiding another loop function. While, you can possibly define another functional loop in your program. Last tip, (optionally) you can use millis() func. instead of delay() for speeding & defining processes on single-core Arduino.

jw0752 · Answer

Hi Sofiia, If you do not need to use an arduino I believe a dedicated circuit using two 555 timers and a flip flop will be able to produce this effect. John

shabaz · Answer

Hi Sofiia,

To do this properly is quite an advanced thing. There's a capability inside the Arduino (it is slightly different depending on which Arduino you are using, but at a high level, the concept is the same) called a timer. The timer can be programmed to generate something called an 'interrupt' which calls a special function (called an interrupt service routine) regularly, for example every second.

Then, you can use a global variable to count these 1-second ticks. Another global variable can be used to store state information related to (say) button press.

Button-presses need debouncing, that is another topic too,

To make a long story short, these two topics will require a lot of reading.

Some resources are here:

Timers and interrupts: https://learn.adafruit.com/multi-tasking-the-arduino-part-2/timers

Button debounce: https://blog.adafruit.com/2009/10/20/example-code-for-multi-button-checker-with-debouncing/

ankur608 · Answer

For simplicity, you can replace your button with 'push on-off' or add an another 'tact switch' for the same. This will make your code routine much easier. Remember things that can't be reached with just CODE, can be easily done out with a little tweak in HARDWARE.

beacon_dave · Answer

Another couple of potentially useful resources: Level Up Your Arduino Code: External Interrupts https://www.youtube.com/watch?v=J61_PKyWjxU Level Up Your Arduino Code: Timer Interrupts https://www.youtube.com/watch?v=2kr5A350H7E This one is not Arduino IDE but still a good introduction to the AVR peripherals such as GPIO and timer/counters: Getting Started With AVR https://www.youtube.com/playlist?list=PLtQdQmNK_0DRhBWYZ32BEILOykXLpJ8tP

sonys · Answer

I made sketches, look, please. I need to add time, but I'm already confused with the millis () function. Correct, if there's a mistake. class PauseFlasher
{
 const unsigned long maxValue = 4294967295UL; // maximum counter value

int ledPin; 
 long OnTime; 
 long OffTime; 
 long PeriodFlashing; 
 long PeriodPause;

int ledState; 
 int ledFlashing; 
 int keyState, oldKeyState; 
 unsigned long previousMillis;
 unsigned long previousFlashingMillis; 
 unsigned long previousKeyMillis;

public:
 PauseFlasher(int pin, long on, long off, long flashing, long pause)
 {
 ledPin = pin;
 pinMode(ledPin, OUTPUT);

OnTime = on;
 OffTime = off;
 PeriodFlashing = flashing;
 PeriodPause = pause;

ledState = HIGH;
 ledFlashing = HIGH;
 keyState = LOW;
 oldKeyState = HIGH;
 previousMillis = 0; 
 previousFlashingMillis = 0; 
 previousKeyMillis = 0;
 }

void Update()
 {
 unsigned long currentMillis = millis(); 
 unsigned long temp_time=0, temp_time1=0;

if (currentMillis >= previousFlashingMillis) temp_time1 = currentMillis - previousFlashingMillis;
 else temp_time1 = maxValue - previousFlashingMillis + currentMillis;

if ((ledFlashing==HIGH) && (temp_time1 >= PeriodFlashing))
 {
 ledFlashing = LOW; 
 previousFlashingMillis = currentMillis; 
 digitalWrite(ledPin, ledFlashing); 
 keyState = LOW;
 oldKeyState= HIGH;
 }
 if ((ledFlashing==LOW) && (temp_time1 >= PeriodPause))
 {
 ledFlashing = HIGH; 
 previousFlashingMillis = currentMillis ; 
 digitalWrite(ledPin, ledFlashing); 
 keyState = LOW;
 oldKeyState= HIGH;
 }

if(ledFlashing==HIGH)
 {
 if (currentMillis >= previousMillis) temp_time = currentMillis - previousMillis;
 else temp_time = maxValue - previousMillis + currentMillis;
 
 if((ledState == HIGH) && (temp_time >= OnTime))
 {
 ledState = LOW; // выключаем
 previousMillis = currentMillis; 
 digitalWrite(ledPin, ledState); 
 }
 else if ((ledState == LOW) && (temp_time >= OffTime))
 {
 ledState = HIGH; // включаем
 previousMillis = currentMillis ; 
 digitalWrite(ledPin, ledState); 
 }
 }
 if(ledFlashing==LOW)
 {
 if (digitalRead(2)==HIGH)
 {
 if(millis()-previousKeyMillis>100)
 {
 previousKeyMillis = millis();
 if(keyState==oldKeyState)
 {
 if(keyState==LOW) keyState=HIGH;
 else if(keyState==HIGH) keyState=LOW;
 digitalWrite(ledPin, keyState);
 } 
 }
 }
 else oldKeyState=keyState;
 }
 }
};

PauseFlasher led1(13, 100, 200, 5000, 15000);

void setup(){}

void loop()
{
 led1.Update();
}

shabaz · Answer

There's no guideline on where to write the values, it just needs to be done wherever you suspect (after running the code and seeing the result for example) there could be an error, or wherever you want to be sure the value is changing as expected.

You can comment them out afterwards if you don't need them after debugging.

shabaz · Answer

Hi Sofiia, There are two 'void loop', one needs removing. You can delete lines 41-46 (that part looks like a test program to blink an LED). Or you can write before line 41: #ifdef my_test and after line 46: #endif You can wrap any area of code you don't want to run like that. (or use // on each line).

sonys · Answer

I checked all the brackets. Everything should work, but the error is still the same. I didn’t work with the millis function, so it’s easier for me to convert via "delay"

Turning on the LED after a while.

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