SpinTimer

Universal Timer with 1 millisecond resolution, supporting OOP principles.

Status

Features

configurable to be either recurring (timer automatically restarts after the interval) or non-recurring (timer stops after timeout period is over)
timer interval/timeout time configurable
attaches automatically in the background to a SpinTimerContext which periodically updates all registered timers' states and performs the timer expire evaluation for each registered timer
based on system uptime (number of milliseconds since the system began running the current program, i.e. Arduino: millis() function or STM32: HAL_GetTick() function); the source of the uptime info [ms] can be overridden by injecting a specific implementation when working with other frameworks than with Arduino
handles system time overflows correctly (unsigned long int type, occurring around every 50 hours)

Integration

Here the integration of a SpinTimer is shown with a simple Arduino Sketch toggling the Arduino board's built-in LED (blink):

include the library

#include <Arduino.h>
#include <SpinTimer.h>

timer interval constant definition

const unsigned int BLINK_TIME_MILLIS = 200;

specific SpinTimerAction implementation, periodically toggling the Arduino built-in LED

class BlinkTimerAction : public SpinTimerAction
{
public:
  void timeExpired()
  {
    digitalWrite(LED_BUILTIN, !digitalRead(LED_BUILTIN));
  }
};

setup: set LED pin to output; create recurring Timer, inject specific SpinTimerAction

//The setup function is called once at startup of the sketch
void setup()
{
  pinMode(LED_BUILTIN, OUTPUT);
  new SpinTimer(BLINK_TIME_MILLIS, new BlinkTimerAction(), SpinTimer::IS_RECURRING, SpinTimer::IS_AUTOSTART);
}

loop: call scheduleTimers() function

// The loop function is called in an endless loop
void loop()
{
  scheduleTimers();
}

Platform specific Uptime Info Adapter injection

When using the SpinTimer library with an Arduino Framework environment the uptime milliseconds counter info default implementation (millis() function) is automatically engaged and nothing has to be done.

If you are using other environments (i.e. when running in an STM32Cube system using STM32 HAL), a specific UptimeInfoAdapter implementation has to be used and injected. The following example shows the specific STM32UptimeInfoAdapterimplementation of UptimeInfoAdapteras to be found in the Examples folder:

/*
 * STM32UptimeInfoAdapter.h
 *
 *  Created on: 30.07.2019
 *      Author: dniklaus
 */

#ifndef STM32UPTIMEINFOADAPTER_H_
#define STM32UPTIMEINFOADAPTER_H_

#include "stm32l4xx_hal.h"   // maybe shall be changed according to your specific STM32 MCU chip in use
#include "UptimeInfo.h"

class STM32UptimeInfoAdapter: public UptimeInfoAdapter
{
public:
  inline unsigned long tMillis()
  {
    unsigned long ms = HAL_GetTick();
    return ms;
  }
};

#endif /* STM32UPTIMEINFOADAPTER_H_ */

Here is how the STM32UptimeInfoAdapter implementation is injected into the UptimeInfo instance:

// ..
#include "STM32UptimeInfoAdapter.h"

int main(void)
{
  HAL_Init();
  SystemClock_Config();
  // ..
  UptimeInfo::Instance()->setAdapter(new STM32UptimeInfoAdapter());  

  // ..
    
  while (1)
  {
    scheduleTimers();
  }    
}

API

This section describes the SpinTimer library Application Programming Interface.

SpinTimer

Constructor: SpinTimer(unsigned long timeMillis, SpinTimerAction* action = 0, bool isRecurring = false, bool isAutostart = false) Will attach itself to the SpinTimerContext (which normally keeps being hidden to the application).
- Parameter timeMillis: Timer interval/timeout time [ms], >0: timer starts automatically after creation, 0: timer remains stopped after creation (timer will expire as soon as possible when started with start()), default: 0
- Parameter action: SpinTimerAction to be injected, is able to emit a timer expired event to any specific listener, default: 0 (no event will be sent)
- Parameter isRecurring: Operation mode, true: recurring, false: non-recurring, default: false
- Parameter isAutostart: Autostart mode, true: autostart enabled, false: autostart disabled, default: false
Attach specific SpinTimerAction, acts as dependency injection. void attachAction(SpinTimerAction* action)
- Parameter action: Specific SpinTimerAction implementation
Timer Action get accessor method. SpinTimerAction* action()
- Returns SpinTimerAction: Object pointer or 0 if no action is attached.
Start or restart the timer with a specific time out or interval time. void start(unsigned long timeMillis)
- Parameter timeMillis: Time out or interval time to be set for the timer [ms]; 0 will make the timer expire as soon as possible.
Start or restart the timer. void start()
- The timer will expire after the specified time set with the constructor or start(timeMillis) before.
Cancel the timer and stop. void cancel()
- No time expired event will be sent out after the specified time would have been elapsed.
- Subsequent isExpired() queries will return false.
Poll method to get the timer expire status, recalculates whether the timer has expired before. bool isExpired()
- This method could be used in a pure polling mode, where tick() has not to get called (by the SpinTimerContext::handleTick() method), but also a mixed operation in combination with calling tick() periodically is possible.
- Subsequent isExpired() queries will return false after the first one returned true, as long as the time did not expire again in case of a recurring timer.
- Returns true if the timer has expired.
Indicates whether the timer is currently running. bool isRunning()
- Returns true if timer is running.
Kick the Timer. void tick()
- Recalculates whether the timer has expired.
Constant for isRecurring parameter of the constructor to create a one shot timer. static const bool IS_NON_RECURRING = false
Constant for isRecurring parameter of the constructor to create a recurring timer. static const bool IS_RECURRING = true

SpinTimerAction

Action Interface, will notify timeExpired() event.
Implementations derived from this interface can be injected into a SpinTimer object.
- the SpinTimer then will call out the specific action's timeExpired() method. Interface sending out a timerExpired() event.
Time expired event. To be implemented by specific SpinTimerAction class. virtual void timeExpired() = 0

UptimeInfoAdapter

Uptime Info Adapter Interface, will call out to tMillis() method to get current milliseconds counter value.
Implementations derived from this interface can be injected into the UptimeInfo singleton object.
Default implementation DefaultUptimeInfoAdapter for Arduino Framework environments is engaged automatically
Call out to get current milliseconds. To be implemented by specific UptimeInfoAdapter class. virtual unsigned long tMillis() = 0