# Coding the light monster

Using the sensitivity of the light sensor and code, let’s make the light monster’s jaw move!

## Concepts

• Sensors (light)
• Pixels
• Pin functions (servo)

## Blocks

light.graph(input.lightLevel(),0)
pins.A2.servoWrite(180)
Math.map(input.lightLevel(),0,0,0,0)
pause(0)

## Step 1: Coding the servo pin connection

2. From LIGHT, drag a graph of block, and place it inside a forever loop.
forever(() => {
light.graph(0, 0)
})

### Build the Block…

From INPUT drag a light level into the graph of block.

forever(() => {
light.graph(input.lightLevel(), 0)
})

From PINS, drag a servo write pin to block and place it inside the forever loop.

forever(() => {
light.graph(input.lightLevel(), 0)
pins.A1.servoWrite(180)
})

### Build the block…

1. Change the value of the pin to A2.
2. From MATH drag out map and place it inside the value for the servo pin to write.
3. Change the value of from high to 255.
4. Change the value of to high to 255.
forever(() => {
light.graph(input.lightLevel(), 0)
pins.A2.servoWrite(Math.map(
input.lightLevel(),
0,
255,
0,
255
))
})

## Step 2: Calibrating the servo motor

If you download the code now, and shine light on the circuit playground, you will see the servo moter turn in a large arc. Let’s try changing the values of the position of the servo motor so that your monster’s jaw will open and close in a reasonable distance!

### Build the block…

1. Change the value of to low to 50.
forever(() => {
light.graph(input.lightLevel(), 0)
pins.A2.servoWrite(Math.map(
input.lightLevel(),
0,
255,
50,
255
))
})

This limits the distance the motor will move. So, whenever light shines on the circuit playground, the monster’s mouth will open and close by a smaller amount.

## Step 3: Adding a pause loop to the function

The pause loop placed in the forever loop causes the code to wait for a short time. This keeps the monster’s mouth from twitching too much. Let’s try using a pause!

From LOOPS drag a pause (ms) block into the bottom of the forever loop.

pause(100)

### Build the block…

1. Change the value of pause to 400.
forever(() => {
light.graph(
input.lightLevel(),
0
)
pins.A2.servoWrite(Math.map(
input.lightLevel(),
0,
255,
0,
255
))
pause(400)
})

## Step 4: Give it a try!

Download the code to Adafruit Circuit Playground Express and try shining a light on it. Take the light away and see what happens too.

Good work! Now your project is complete and ready to show off. Have fun playing with your new monster!