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

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2016-03-26 00:47:20 +01:00
# flashing heart activity
Ccontrol images with variables.
### ~avatar avatar
### @video td/videos/flashing-heart-0
In this activity, you will learn how to blink an image on the LED screen.
### ~
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)
})
```
### ~avatar boothing
2016-04-13 17:27:45 +02:00
Excellent, you're ready to continue with the [challenges](/lessons/flashing-heart/challenges)!
2016-03-26 00:47:20 +01:00
### ~