diff --git a/usb/pulse-leds.js b/usb/pulse-leds.js
index 038a47f4..fb9028f9 100755
--- a/usb/pulse-leds.js
+++ b/usb/pulse-leds.js
@@ -28,51 +28,142 @@ var state = 1;
 
 var ledsLeft = new Buffer(ledMatrixSize);
 var ledsRight = new Buffer(ledMatrixSize);
+ledsLeft.fill(0)
+ledsRight.fill(0)
 
 var ledIndex = 0;
 var matrixId = 0;
 
+function disableUnusedLeds() {
+    var buffer = new Buffer([
+        writeLedDriverCommandId,
+        leftLedDriverAddress,
+        19,
+        0,
+        0, 0b00111111,
+        0, 0b00111111,
+        0, 0b00111111,
+        0, 0b00011111,
+        0, 0b00011111,
+        0, 0b00011111,
+        0, 0b00011111,
+        0, 0b00011111,
+        0, 0b00011111,
+    ]);
+
+    endpointOut.transfer(buffer, function(err) {
+        if (err) {
+            console.error("USB error: %s", err);
+            process.exit(1);
+        }
+        updateLeds();
+    });
+}
+
 function updateLeds() {
-    console.log('update')
-    endpointOut.transfer(Buffer.concat([
+//    console.log('update')
+    var buffer = Buffer.concat([
         new Buffer([
             writeLedDriverCommandId,
             matrixId ? rightLedDriverAddress : leftLedDriverAddress,
             ledCountToUpdatePerCommand,
             0x24 + ledIndex
         ]),
-        (matrixId ? ledsRight : ledsLeft).slice(ledIndex, ledCountToUpdatePerCommand)
-    ]), function(err) {
+        (matrixId ? ledsRight : ledsLeft).slice(ledIndex, ledIndex + ledCountToUpdatePerCommand)
+    ]);
+    console.log('iter: '+i+' out:', util.bufferToString(buffer))
+    endpointOut.transfer(buffer, function(err) {
         if (err) {
             console.error("USB error: %s", err);
             process.exit(1);
         }
-        console.log('update success')
+//        console.log('update success')
         endpointIn.transfer(64, function(err2, receivedBuffer) {
             if (err2) {
                 console.error("USB error: %s", err2);
                 process.exit(2);
             }
-            console.log('Received', util.bufferToString(receivedBuffer));
+//            console.log('Received', util.bufferToString(receivedBuffer));
 
             ledIndex += ledCountToUpdatePerCommand;
             if (ledIndex >= ledMatrixSize) {
                 ledIndex = 0;
+                matrixId = matrixId ? 0 : 1;
             }
-            matrixId = matrixId ? 0 : 1;
 
             updateLeds();
         })
     });
 }
 
-updateLeds();
+disableUnusedLeds();
+
 var i = 0;
-setInterval(function() {
-    console.log('iter')
-    ledsLeft.fill(0)
+
+var lettersLeds = {
+    0: [1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1],
+    1: [0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0],
+    2: [1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1],
+    3: [1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1],
+    4: [0, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0],
+    5: [1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1],
+    6: [1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1],
+    7: [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0],
+    8: [1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1],
+    9: [1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1],
+    A: [1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0],
+    B: [1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1],
+    C: [1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1],
+    D: [1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1],
+    E: [1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1],
+    F: [1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0],
+    G: [1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1],
+    H: [0, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0],
+    I: [0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0],
+    J: [0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1],
+    K: [0, 1, 0, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0],
+    L: [0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1],
+    M: [0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0],
+    N: [0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0],
+    O: [1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1],
+    P: [1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0],
+    Q: [1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 1],
+    R: [1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0],
+    S: [1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1],
+    T: [1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0],
+    U: [0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1],
+    V: [0, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0],
+    W: [0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0],
+    X: [0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0],
+    Y: [0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0],
+    Z: [1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1],
+}
+
+var iconLedsToLedMatrix = [0x08, 0x09, 0x0a];
+var layerLedsToLedMatrix = [0x0d, 0x1d, 0x2d];
+
+var characterLedsToLedMatrix = [
+    [0x0b, 0x1b, 0x29, 0x2a, 0x2b, 0x0c, 0x1c, 0x28, 0x1a, 0x2c, 0x38, 0x39, 0x18, 0x19],
+    [0x3a, 0x4a, 0x58, 0x59, 0x5a, 0x3b, 0x4b, 0x4c, 0x49, 0x5b, 0x5c, 0x68, 0x3c, 0x48],
+    [0x69, 0x79, 0x7c, 0x88, 0x89, 0x6a, 0x7a, 0x7b, 0x78, 0x8a, 0x8b, 0x8c, 0x6b, 0x6c]
+]
+
+function setLetter(letterLeds, position) {
+    for (var i=0; i<14; i++) {
+        ledsLeft[characterLedsToLedMatrix[position][i]] = letterLeds[i] ? 0xff : 0;
+    }
+}
+
+setLetter(lettersLeds['A'], 0);
+setLetter(lettersLeds['B'], 1);
+setLetter(lettersLeds['C'], 2);
+
+/*setInterval(function() {
+//    console.log('iter', i);
+    ledsLeft.fill(0);
     ledsLeft[i] = 0xff;
     if (++i >= ledMatrixSize) {
         i = 0;
     }
-}, 100)
+}, 100);
+*/
\ No newline at end of file