Hello World for Max72xx and a 4 digit 7-segment display (Electric Imp device code)

device.txt

// Hello World for Max72xx and a 4 digit 7-segment display (Electric Imp device code)

hardware.pin7.configure(DIGITAL_OUT);
hardware.spi189.configure(SIMPLEX_TX, 10000);

function send(data) {
    hardware.pin7.write(0); // set CS before sending data
    hardware.spi189.write(data);
    hardware.pin7.write(1); // release CS after sending data
}
function configure() {    
    send("\x0C\x00");   // shutdown on
    //send("\x0F\x01");   // display_test on 
    send("\x0F\x00");   // display_test normal
    send("\x09\x0F");   // decode mode
    send("\x0A\x0F");   // intensity
    send("\x0B\x03");   // scanlimit
    send("\x0C\x01");   // shutdown normal
}
configure();

function blankDisplay() {
    send("\x01\x0F");
    send("\x02\x0F");
    send("\x03\x0F");
    send("\x04\x0F");
}
blankDisplay();

function getNumberByte(digit, num) {
    local digit_blob = blob(2);
    digit_blob.writen(digit, 'b');
    digit_blob.writen(num, 'b');
    return digit_blob;
}
function sendNumber(num) {
    local digit1 = num % 10;
    send(getNumberByte(4, digit1));
    local digit2 = (num / 10) % 10;
    send(getNumberByte(3, digit2));
    local digit3 = (num / 100) % 10;
    send(getNumberByte(2, digit3));
    local digit4 = (num / 1000) % 10;
    send(getNumberByte(1, digit4));
    //server.log(num);
}

local vv = 0;
function counter() {
    vv = vv + 1;
    sendNumber(vv);
    imp.wakeup(0.03, counter);
}

counter();



// watchdog keeps the imp from going to sleep
function watchdog() {
    imp.wakeup(5*60, watchdog);
    server.log("watchdog");
}
watchdog();

imp.configure("4 Digit Display", [], []);