# Use Blinkt to show door open or closed

**URL:** <https://forums.pimoroni.com/t/use-blinkt-to-show-door-open-or-closed/3633>\
**Category:** Support\
**Created:** [December 24, 2016, 10:15pm UTC](https://forums.pimoroni.com/t/use-blinkt-to-show-door-open-or-closed/3633 "2016-12-24T22:15:36Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![Richard238](https://avatars.discourse-cdn.com/v4/letter/r/c68b51/32.png) [@Richard238](https://forums.pimoroni.com/u/Richard238)\
**Post date:** [December 24, 2016, 10:15pm UTC](https://forums.pimoroni.com/t/use-blinkt-to-show-door-open-or-closed/3633/1 "2016-12-24T22:15:37Z")

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How would I code Blinkt to show red if a door’s closed, and green if it’s open?

I can do the magnetic switch OK, but can’t figure the code to get Blinkt to respond to changes in GPIO status.

Thank you.

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**Author:** ![Richard238](https://avatars.discourse-cdn.com/v4/letter/r/c68b51/32.png) [@Richard238](https://forums.pimoroni.com/u/Richard238)\
**Post date:** [December 29, 2016, 7:43pm UTC](https://forums.pimoroni.com/t/use-blinkt-to-show-door-open-or-closed/3633/2 "2016-12-29T19:43:50Z")

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Anyone? Must be possible…

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**Author:** ![major\_tomm](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/major_tomm/32/9044_2.png) [@major\_tomm](https://forums.pimoroni.com/u/major_tomm)\
**Post date:** [December 29, 2016, 8:36pm UTC](https://forums.pimoroni.com/t/use-blinkt-to-show-door-open-or-closed/3633/3 "2016-12-29T20:36:54Z")

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You just want a loop continually reading the GPIO status and re-acting accordingly:

```
import RPi.GPIO as GPIO
from blinkt import *
GPIO.setmode(GPIO.BCM)
GPIO.setup(4, GPIO.IN)

while True:
    switch_open = GPIO.input(4)
    if switch_open:
        for i in range(8):
            set_pixel(i , 0, 255, 0)
    else:
        for i in range(8):
            set_pixel(i , 255, 0, 0)

    show()
```

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**Author:** ![RogueM](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/roguem/32/311_2.png) [@RogueM](https://forums.pimoroni.com/u/RogueM)\
**Post date:** [December 29, 2016, 10:03pm UTC](https://forums.pimoroni.com/t/use-blinkt-to-show-door-open-or-closed/3633/4 "2016-12-29T22:03:22Z")

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was about to post an example too (using gpiozero and a button but same principle).

Note that you can use the `set_all()` function if you want all pixels to be the same colour.

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**Author:** ![Richard238](https://avatars.discourse-cdn.com/v4/letter/r/c68b51/32.png) [@Richard238](https://forums.pimoroni.com/u/Richard238)\
**Post date:** [December 29, 2016, 10:41pm UTC](https://forums.pimoroni.com/t/use-blinkt-to-show-door-open-or-closed/3633/5 "2016-12-29T22:41:06Z")

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Brilliant! Thank you, I’ll look at those over the next few days.

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**Author:** ![major\_tomm](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/major_tomm/32/9044_2.png) [@major\_tomm](https://forums.pimoroni.com/u/major_tomm)\
**Post date:** [December 29, 2016, 11:44pm UTC](https://forums.pimoroni.com/t/use-blinkt-to-show-door-open-or-closed/3633/6 "2016-12-29T23:44:08Z")

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No worries, thought there might be a `set_all` type function, but the blinkt example I grabbed didn’t have an example of it :)

Just be mindful of whether your reed-switch (or equivalent) is wired up as pull-up or pull-down as it will affect the logic in my example.

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<div class="post-metadata">

**Author:** ![Richard238](https://avatars.discourse-cdn.com/v4/letter/r/c68b51/32.png) [@Richard238](https://forums.pimoroni.com/u/Richard238)\
**Post date:** [January 2, 2017, 4:42pm UTC](https://forums.pimoroni.com/t/use-blinkt-to-show-door-open-or-closed/3633/7 "2017-01-02T16:42:59Z")

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That works just fine, thank you.

The set\_all function is documented here: [https://github.com/pimoroni/blinkt/blob/master/documentation/REFERENCE.md](https://github.com/pimoroni/blinkt/blob/master/documentation/REFERENCE.md)

How do you make it switch the LEDs off when you kill the script?

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<div class="post-metadata">

**Author:** ![RogueM](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/roguem/32/311_2.png) [@RogueM](https://forums.pimoroni.com/u/RogueM)\
**Post date:** [January 2, 2017, 7:20pm UTC](https://forums.pimoroni.com/t/use-blinkt-to-show-door-open-or-closed/3633/8 "2017-01-02T19:20:02Z")

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Try something like this:

> <https://github.com/pimoroni/blinkt/blob/master/examples/graph.py>

… note there’s a dedicated doc site for a number of Pimoroni libs, with more added as time permits:

[https://docs.pimoroni.com](https://docs.pimoroni.com)