electric imp code for ac dimming circuit

acdimmer

// Electric Imp code example - AC dimmer
 
// Define zero crossing period = 1 / Mains Freq / 2
// 60Hz = 0.008333, 50Hz = 0.01
const ZEROT = 0.008333;
 
local pinZerox = hardware.pin9;     // Pin to use as zero cross input
local pinTriac = hardware.pin2;     // Pin to use for triac control
local level = 0.5;                  // Dimmer level 0.0 = Off, 1.0 = Full bright
local tic=0;
local toc=0;

// Derive our input class from InputPort
class input extends InputPort
{
    function set(newLevel)
    {
        // Validate and store the new level
        if(newLevel < 0.0) newLevel = 0.0;
        if(newLevel > 1.0) newLevel = 1.0;
        level = newLevel;
 
        // Display level on the Planner node
        server.show(format("%3.1f%%", level * 100.0));
    }
}

// Zero crossing event handler, called every time the AC output crosses 0V
function zeroxEvent()
{
    // ignore falling edge
    if(pinZerox.read() == 0) return;
    
    // ignore rising edge
    //if(pinZerox.read() > 0) return;
    
    
    tic = tic +1;
    if(tic>120) {
        tic=0;
        toc=toc+1;
        server.show(format("%d secs %3.1f%%", toc, level * 100.0));
    }
    
    // Leave triac off for levels < 0.05
    //if(level < 0.05)
    //{
    //    pinTriac.write(1);
    //    return;
    //}
 
    // "chop off": turn off the triac
    pinTriac.write(0);
 
    // Leave triac on for levels > 0.95
    if(level < 0.25) return;
 
    // Otherwise sleep for part of the AC cycle 
    imp.sleep(ZEROT * (1.0-level));
    //imp.wakeup(ZEROT * (1.0-level), chopOn);

    // "chop on": turn the triac on and leave on until next zero cross
    pinTriac.write(1);
}
 
function chopOn() {
    pinTriac.write(1);
}

//function watchdog() {
//imp.wakeup(60,watchdog);
//server.log("watchdog");
//}
//
//// start watchdog write every 60 seconds
//watchdog();

// Configure pin functions
pinTriac.configure(DIGITAL_OUT);
pinZerox.configure(DIGITAL_IN, zeroxEvent);
 
// Register with the server
imp.configure("AC Dimmer", [input("Level", "number")], []);
 
// Initialise the node display
//server.show("0%");
server.show(format("%3.1f%%", level * 100.0));

// End of code.