Use of timer interrupts in arduino stop the serial library functions why?

Question

I am working with an arduino project.I am using timer interrupts and Serial communication.But as soon as the timer interrupts enables arduino Serial library functions are not working.I am stuck with this problem. Is there any way to do this. I want to use both Serial communication and timer interrupts.Use of the following function stops the Serial communication

    void initialize()
    {
    //timer0
     TIMSK0 = 2;                             
     OCR0A = 125;                             
    TCCR0A = 0b00000010;   //commenting TCCR0A = 0b00000010; and  TIMSK1 = 1 ; enable
    TCCR0B = 0b00000011;   // the serial communications

    //timer1
    TCCR1B = 1 ;                                
   TIMSK1 = 1 ;                                         


   //timer2
     TCCR2A = _BV(COM2A0) | _BV(WGM21) | _BV(WGM20);
     TCCR2B = _BV(WGM22) | _BV(CS20);
    OCR2A = B11000111; 


     EICRA = 63 ;                                        
      EIMSK = (1 << INT0) | (1 << INT1);  
      }

can you isolate which actual command causes the serial to stop working? Is it really both, needed to work. I would also recommend not messing with timer0, as it is used by the Arduino Core libraries for other functions such as the millisecond counter. Hence I would suspect that TIMSK1 does not affect it. — mpflaga
Sorry, that was a mistake. The above function stops not only the Serial library but the entire things in arduino. I don't know much about timers. I don't want to use any functions like millis() that are messing with timer0 other than Serial library functions. — Rijo Kuriakose
I need timer0 to give me a 0.5 mS tick, timer1 to calculate the delay of ultra sonic sound and timer2 for generating an oscillation of 40Khz. Is there any single library which simplifies the use of the all three timers and interrupts? — Rijo Kuriakose

mpflaga mpflaga · Accepted Answer · 2013-12-21T19:39:42

I would avoid using Timer0, directly. As it will mess with Arduino Core Libraries, as you are seeing.

On initial glance I would suggest using a proven library such as SimpleTimer(). It will setup and manage multiple events where its "run" basically pulls the millis() from timer 0. But read farther down.

I recall that Timer0 is setup by the core library to overrun at 1K creating interrupt. Where the micros() function read the value within timer0 between millisecond interrupts.

And for using Timer1 you can try TimerOne() library. There are also TimerTwo, 3 and etc.. out there.

You may want to read through Ken Shirriff's Arduino-IRremote library. As it does much of what you want, in discrete methods. Such as the 40Khz PWM. Rather than depending upon other libraries. Where his original library uses a

USECPERTICK 50  // microseconds per clock interrupt tick

to read and sample the receive input from a IR demodulator, as to decode the frames.

I would also point out microtherion's fork of the library, as it uses pin change interrupts to get more accurate pin changes. Where his library, again discretely manages these interrupts.

Were as one could use PinChangeInt Library to setup your implementation. Where the individual pin changes' ISR could capture the time stamp almost immediately. Minus latency where in this case is much less the 50ms desired resolution.

And if you really needed more resolution you can use the Input Capture Function. As demonstrated in InputCapture.ino. Which will capture the time of transition in real-time and generate an ISR for latent handling.

From these examples you should be able to implement your ultra sonic sensor.

Use of timer interrupts in arduino stop the serial library functions why?

2 Answers