### Project 22 Noise Meter

**1.  Description**

Arduino noise meter embodies the sound signal to a series of dots, which are converted into patterns displayed on dot matrix. 

**2. Wiring Diagram**

![](media/B63.png)

**3. Test Code**

1. Drag the basic blocks and initialize the display. Set the pin CS to IO15 and brightness to 3. Then add a variable block and select int and name it as "item" with an initial assignment of 0.

2. Add a variable block and name it as "item". Adopt a map function to convert the read sound value range from 0-4095 to 0-7, yet the hypothesis maximum value of sound is 800.

![](media/B64.png)

3. Clear the display. 

4. Program a condition. If the variable item is greater than -1, the dot matrix displays (x0:0  y0:0 x1:1  y1:0) in color of red.

![](media/B65.png)

5. Repeat step 4, but the judgment is whether item is greater than 0. If so, dots at (x0:1  y0:0  x1:1  y1:1) will light up. By that analogy, build code blocks referring to the following coordinates. 

6. Finally, refresh the display. 

**Reference Coordinates:**

![](media/B66.png)

![](media/B67.png)

**Complete Code:**

![](media/B68.png)

**4. Test Result**

After connecting the wiring and uploading code, the noise level view is displayed on dot matrix, as shown below.

![](media/B69.png)![](media/B70.png)![](media/B69.png)![](media/B70.png)