# 1.3 Happy Birthday

When the button is pressed, the candles on the cake light up; when the button is released, the candles on the cake go out.

![](./img/1.3/1.3_cake1.png)

## Required Components

![](./img/1.3/1.3_list.png)

## Build the Circuit

![](./img/1.3/1.3_fritzing.png)

## Load the Code and See What Happens

After loading the code file (`1.3_happy_birthday.sb3`) into Scratch 3.Click the green flag.When the button is pressed, the candles on the cake light up; when the button is released, the candles on the cake go out.

## Tips on Sprite

Click on the **Choose a Sprite**.

![](./img/1.3/1.3_sprite.png)

Enter **cake**, click search, and select the Sprite named Cake.

![](./img/1.3/1.3_sprite1.png)

## Tips on Codes

LED lights go out when the GPIO17 outputs LOW. Cake sprite switch to Cake B (the candle is not lit)

<img src="./img/1.3/1.3_code.png" style="zoom:88%;" />

When the GPIO17 outputs high, the LED light is on. Cake sprite switch to Cake A (candle is lit)

![](./img/1.3/1.3_code1.png)

When the keys are pressed, GPIO18 is LOW. When the keys are not pressed, GPIO18 is HIGH.

![](./img/1.3/1.3_code2.png)