rpi-led-control.js
function clearDisplay(addr) {
	    if(addr<0 || addr>=maxDevices)
			throw 'address out of range';
		
	    var offset;
			
	    offset=addr*8;
	    for(var i=0;i<8;i++) {
			status[offset+i]=0;
			spiTransfer(addr, i+1,status[offset+i]);
	    }
	}
function clearDisplay(addr) {
	    if(addr<0 || addr>=maxDevices)
			throw 'address out of range';
		
	    var offset;
			
	    offset=addr*8;
	    for(var i=0;i<8;i++) {
			status[offset+i]=0;
			spiTransfer(addr, i+1,status[offset+i]);
	    }
	}
clears the entire display