Sony Arouje

Recent days I was playing with my Arduino uno to perform several tasks. One task is something like, say sleep for 10 mins and switch on a pin for 3 mins then sleep for 10 mins, and the cycle continues. I evaluated several libraries but most of them run a task based on an interval. For e.g. toggle pin 13 every 1 minute, it’s more like a delay. But what I wanted was, delay for 2 minutes then give a HIGH voltage to pin 13 for 1 minute then write LOW to pin 13 and again sleep for 10mins.

My search leads nothing, so I decided to write a quick and dirty Scheduler for me. I came up with a library after spending 3 hours yesterday night. I didn’t had much programming experience in C++, so I had to spend some time to understand how things work in C++ world. I also use the Timer library as a reference.

Let’s see the sketch that use my library.

#include "TaskScheduler.h"

TaskScheduler t1;
TaskScheduler t2;
TaskScheduler t3;

void setup() {
  Serial.begin(9600);
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  
  t1.sleepThenToggle(4000,1000,13,HIGH);
  t2.every(2000,readSensor);
  t3.write(12,HIGH,4000);
}

void readSensor(){
  Serial.println("Reading sensors...");
}

void loop() {
  t1.update();
  t2.update();
  t3.update();
}

Here I declared three tasks, t1, t2 and t3.

Task t1 is a toggle pin task with sleep, in the sample code above, Arduino sleeps for 4000ms then switch on pin 13 for 1000ms and the cycle continues.

• sleepThenToggle(<sleep time>,<keep the pin state for x ms>,<pin number>,<starting state of the pin>);

Task t2 is a callback task, in the above case, the function readSensor will get called every 2000ms.

• every(<sleeptime>,<callback>);

Task t3 is a digitalWrite with timeout. One scenario we can use that functionality is, say the switching on/off of a pin is based on an external command, it might be coming from a Raspberry pi. In a situation if the Pi went down with some reason after issuing a switch on command then Arduino will keep the Pin on till a reset. These scenarios, we can use write, in the above code, the pin 12 will be HIGH for 4000ms, after that it will get switched off automatically.

• t3.write(<pin number>,<starting state of the pin>,<timeout period>);

Make sure to call the ‘update()’ in the loop, other wise no action will be taken.

For the curious minds visit my Gitrepo to see the code.

Happy coding…