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1.6 Water Lamp

Today, we will use LED Bar Graph, Raspberry Pi and scratch to make a Water Lamp.

The LED Bar Graph will light up in order with the direction of the arrows on the stage.

../_images/1.12_header.png

Required Components

../_images/1.12_list.png

Build the Circuit

../_images/1.12_image66.png

Load the Code and See What Happens

Load the code file (1.6_water_lamp.sb3) from your computer to Scratch 3.

By clicking on Arrow1, the LEDs on the LED bar are lit in sequence from the left to the right (one at a time) and then off. Click Arrow2 and the LEDs light up in the opposite order.

Tips on Sprites

Delete the default sprite and choose the Arrow1 sprite.

../_images/1.12_graph1.png

Here we will need 2 Arrow1 sprites, which can be done with the duplicate button.

../_images/1.12_scratch_duplicate.png

Click on the Arrow 2 sprite and change the direction of the arrow by selecting costume 2.

../_images/1.12_graph2.png

Now let’s make a variable.

../_images/1.12_graph3.png

Name it as num.

../_images/1.12_graph4.png

Follow the same method to create a list called led.

../_images/1.12_graph6.png

After adding, you should see the num variable and the led list on the stage area.

Click + to add 10 list items and enter the pin numbers in order (17,18,27,22,23,24,25,2,3,8).

../_images/1.12_graph7.png

Tips on Codes

../_images/1.12_graph10.png

This is an event block that is triggered when the current sprite is clicked.

../_images/1.12_graph8.png

The initial value of the num variable determines which LED is lit first.

../_images/1.12_graph9.png

Set the pin corresponding to num in the led list to low to light the LED, and then set the pin corresponding to num-1 to high to turn off the previous LED.