rpi-led-control.js
function setDigit(addr, digit, value, dp){
	    if(addr<0 || addr>=maxDevices)
			throw 'address out of range';
		if(digit<0 || digit>7) 
			throw 'invalid digit number'; 
		if(value<0 || value >15) throw 'number out of range'; 
			
		var offset = addr*8;
		var v = charTable[value];//.toString(16)]; 

		if(dp) v|=0x80; // set the decimal point bit if necessary
		
		status[offset+digit] = v; 
		spiTransfer(addr, digit+1, v); 
	
	}
function setDigit(addr, digit, value, dp){
	    if(addr<0 || addr>=maxDevices)
			throw 'address out of range';
		if(digit<0 || digit>7) 
			throw 'invalid digit number'; 
		if(value<0 || value >15) throw 'number out of range'; 
			
		var offset = addr*8;
		var v = charTable[value];//.toString(16)]; 

		if(dp) v|=0x80; // set the decimal point bit if necessary
		
		status[offset+digit] = v; 
		spiTransfer(addr, digit+1, v); 
	
	}
/*
Display a hexadecimal digit on a 7-Segment Display
Params:
addr	address of the display
digit	the position of the digit on the display (0..7)
value	the value to be displayed. (0x00..0x0F)
dp	sets the decimal point.