pxt-calliope/docs/reference/js/lessons/flashing-heart/activity.md

flashing heart activity

Ccontrol images with variables.

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@video td/videos/flashing-heart-0

In this activity, you will learn how to blink an image on the LED screen.

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Let's start by adding code that plots a heart image on the screen using basic->plot image. Once you are done coding, don't forget to run your code in the simulator or the BBC micro:bit.

basic.plotImage(`
. # . # .
# # # # #
# # # # #
. # # # .
. . # . .
`) // ***

We want to leave the image on the screen for 0.5 seconds (500 milliseconds), then clear the screen. We can use basic->pause to wait and basic->clear screen to turn off the LEDs.

basic.plotImage(`
. # . # .
# # # # #
# # # # #
. # # # .
. . # . .
`)
basic.pause(500) // ***
basic.clearScreen() // ***

Finally, we can surround this code with a basic->forever loop to repeat it and add a pause after basic->clear screen to keep the screen off for a little while. Modify your code so that your code looks like this.

basic.forever(() => {
    basic.plotImage(`
. # . # .
# # # # #
# # # # #
. # # # .
. . # . .
`)
    basic.pause(500)
    basic.clearScreen()
    basic.pause(500)
})

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Excellent, you're ready to continue with the challenges!

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