FrequencyTimer2 in miliseconds

Forum 2005-2010 (read only) Software Development
#1

Since this library sets timer2 interrupt using microseconds and not letting you counting in seconds, i've written a wrapper to allow this.

static unsigned int _msecs = 0;
static void (*_func)() = 0;

void _overFlow();
void Timer2Init();
void Timer2Func(void (*f)());
void Timer2Ms(unsigned int msecs);

void _overFlow() {
  static unsigned int _counter = 0;
  
  _counter += 1;
  
  if ((_counter % (_msecs*2)) == 0) {
    _counter = 0;
    (*_func)();
  }
}

void Timer2Init() {
  FrequencyTimer2::setPeriod(1000);
  FrequencyTimer2::setOnOverflow(_overFlow);
}

void Timer2Func(void (*f)()) {
  _func = f;
}

void Timer2Ms(unsigned int msecs) {
  _msecs = msecs;
}

How to use? it's very easy:

void flashLed() {
  static boolean value = HIGH;
  digitalWrite(13, value);
  value = !value;
}
  
void setup() {
  pinMode(13, OUTPUT);
  Timer2Init();
  Timer2Ms(1000); // overflow each second
  Timer2Func(flashLed);
}

void loop() {
}

Do you like it?

#2

woot, 2nd version, now with multiple triggers for the same timer!

// up to 5 "virtual" overflows with the same timer
#define _TIMERS 5

static unsigned int _msecs[_TIMERS];
static unsigned int _counters[_TIMERS];
static void (*_funcs[_TIMERS])();

void _overFlow();
void Timer2Init();
void Timer2Func(byte num, void (*f)());
void Timer2Ms(byte num, unsigned int msecs);  // msecs = 0 for disabling


void _overFlow() {
  byte tmp;
  
  for(tmp = 0; tmp < _TIMERS; tmp++) {
    if (_msecs[tmp] > 0) {
      _counters[tmp] += 1;
      if ((_counters[tmp] % (_msecs[tmp]*2)) == 0) {
        _counters[tmp] = 0;
        (*(_funcs[tmp]))();
      }
      }
  }
}

void Timer2Init() {
  byte tmp;
  
  for(tmp = 0; tmp < _TIMERS; tmp++) {
        _msecs[tmp] = 0;
      _funcs[tmp] = 0;
      _counters[tmp] = 0;
  }
  
  FrequencyTimer2::setPeriod(1000);
  FrequencyTimer2::setOnOverflow(_overFlow);
}

void Timer2Func(byte num, void (*f)()) {
  _funcs[num] = f;
}

void Timer2Ms(byte num, unsigned int msecs) {
  _msecs[num] = msecs;
}

And a simple example:

void flash() {
  static boolean output = HIGH;
  
  digitalWrite(13, output);
  output = !output;
}

void flash2() {
  static boolean output = HIGH;
  
  digitalWrite(12, output);
  output = !output;
}

void setup() {
  pinMode(12, OUTPUT);
  pinMode(13, OUTPUT);
  Timer2Init();
  Timer2Ms(0, 1000);  // flash a led each second
  Timer2Func(0, flash);
  Timer2Ms(1, 3000);
  Timer2Func(1, flash2);  // flash a led each 3 seconds
}

void loop() {
}
#3

Now that v2 looks really nice.

#4

thanks, i only hope future versions of arduino compiler support something similar since it's more user-friendly IMO

#5

thanks, i only hope future versions of arduino compiler support something similar since it's more user-friendly IMO

It's absolutely must have for any sort of real-time programming. When I first got started with Arduino, that was the first functionality I needed, luckily someone here pointed me to FrequencyTimer2 very quickly.

That bug in the library of calling the handler twice as often as it should really threw me for a while though.

#6

tigrezno,
I’m interested in what you’re doing here. Thanks! So I wanted to try it.
I think I’m being a little naive here, I just took your wrapper and the example and put them together into one sketch. (example first) I also added “#include <FrequencyTimer2.h>”
I get the following compile error:
In function ‘void setup()’:
error: ‘Timer2Func’ was not declared in this scope

. . . which is weird since there is a “Timer2Func” in the wrapper.
(Not that I understand it yet :))

(I even got a “fresh copy” of FrequencyTimer2)

Any help is appreciated

#7

BroHogan, i've already done a stand-alone version (and better) that i'll post in an hour or so.

#8

check the library here: http://www.arduino.cc/playground/Main/MsTimer2 i hope you like it

#9

tigrezno,

Nice timer! Great way to earn your second star! 8-)

I am running it (at 1Ms) in a pretty demanding application with lots of stuff going on.

When I was using FrequencyTimer2 in the same ap, I had to be careful with some things or I would cause a reboot.

I no longer have this issue with this timer. Thanks!

#10