digitalToggle(uint8_t pin)

[Daniel De Kock]

i Know there is a library called "digitalToggle" that enables one to toggle a pin, But I found it easier to add the function to my Wiring_digital.c and Arduino.h in the core
I copied digitalWrite and changed a line to get a toggle method:

void digitalToggle(uint8_t pin)
{
    uint8_t timer = digitalPinToTimer(pin);
    uint8_t bit = digitalPinToBitMask(pin);
    uint8_t port = digitalPinToPort(pin);
    volatile uint8_t *out;

    if (port == NOT_A_PIN) return;

    // If the pin that support PWM output, we need to turn it off
    // before doing a digital write.
    if (timer != NOT_ON_TIMER) turnOffPWM(timer);

    out = portOutputRegister(port);

    uint8_t oldSREG = SREG;
    cli();
   
    if(*out & bit){ // This is all that is different from digitalWrite
    *out &= ~bit;
    }
    else{
    *out |= bit;
    }
   
    SREG = oldSREG;
}

I have been using toggling a lot to make heartbeat LEDs or to reverse motor directions etc.

it might be useful to others.

I only discovered "http://playground.arduino.cc/Code/DigitalToggle" afterwards :(

[Rob Tillaart]

    [code]

    if(*out & bit){ // This is all that is different from digitalWrite
    *out &= ~bit; 
    }
    else{ 
    *out |= bit;

    }[/code]

==>

*out ^= bit;   ??

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[Daniel de Kock]

XOR bit toggle will work too :)

( should be faster and lower code footprint too )

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[Mikael Patel]

Writing the pin register is the fastest method. *pin = mask. 

https://github.com/mikaelpatel/Cosa/blob/master/cores/cosa/Cosa/OutputPin.hh#L150

https://github.com/mikaelpatel/Cosa/blob/master/examples/Benchmarks/CosaBenchmarkPins/CosaBenchmarkPins.ino#L558

Cheers, Mikael