# Bit Level

Let's use Webduino Bit to make a level.      

Webduino Bit has a gyroscope, which can be used to detect the angles of X-axis and Y-axis of the board. It has also a LED matrix, which can reflect those angles. So we can combine these two features to make a level. Let's go!

# Gyroscope

Webduino Bit has an MPU-9250 chip. The MPU-9250 contains a 3-axis gyroscope which can be used to detect the angles of X-axis (roll) and Y-axis (pitch). Refer to the following picture.

Let's create a simple blockly program. Code Link

This program can detect the roll and pitch values. Its JS code is as follows.

var mpu9250;


boardReady({board: 'Bit', device: 'bit77730e', transport: 'mqtt', multi: true}, function (board) {
  board.samplingInterval = 250;
  mpu9250 = getMPU9250(board);
  mpu9250.on(webduino.module.MPU9250Event.ANGLE_MESSAGE, function () {
    document.getElementById("demo-area-01-show").innerHTML = (['row:',mpu9250.angVals[0],("<br/>"),'pitch:',mpu9250.angVals[1]].join(''));
  });
});

# LED Matrix

Webduino Bit has a 5x5 LED matrix. Let's try to create a simple blockly program to light a single LED. Code Link

Let's see its JS code.

var matrix;

boardReady({board: 'Bit', device: '1234', multi: true, transport: 'message', window: window.top.frames[0]}, function (board) {
  board.samplingInterval = 250;
  matrix = getMatrix(board, 4, 25);
  matrix.setColor((4 - 1 + ( 2 - 1) * 5 ), '#33ff33');
});

Note that in blockly program, the range of row and column is from 1~5. While in JS code, its index is from 0~4. This is why you see the formula: ((4-1)+(2-1)5). It means the LED position of (4, 2) has index (3, 1) and position number (3+15=8).

# Combined gyroscope and LED

Now we can combine the above codes of gyroscope and LED maxtrix to make a Bit level. I add a little logic to quantize the roll and pitch values to the range 1~5. The codes and result are shown in the following. Note that to see the correct result, you need to connect the Bit board to Wi-Fi first. Then you can jump into the jsFiddle and change the Device ID to yours. After that, just run the codes. That's it!