# Using Jacdac LED blocks in ON START

**URL:** https://forum.makecode.com/t/using-jacdac-led-blocks-in-on-start/14642
**Category:** Jacdac
**Created:** [July 29, 2022, 5:28pm UTC](https://forum.makecode.com/t/using-jacdac-led-blocks-in-on-start/14642 "2022-07-29T17:28:53Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![dsssssssss9](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/dsssssssss9/32/861_2.png) [@dsssssssss9](https://forum.makecode.com/u/dsssssssss9)
#### Post date: [July 29, 2022, 5:28pm UTC](https://forum.makecode.com/t/using-jacdac-led-blocks-in-on-start/14642/1 "2022-07-29T17:28:53Z")

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someone mentioned ( not sure it here or on Github ) that whenever they put any Jacdac LED blocks in ONSTART they led did not light up.

I seem to remember someone else thought it might be due to the Jacdac software not fully starting until after the ONSTART had finished?

I have found that if you put a SET LED BRIGHTNESS block, with a value greater than 0 ,before any LED block in ONSTART, the led will now display

I don’t know if this applies to the previous versions of Jacdac as well but thought it might be useful for someone!

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### Author: ![peli](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.makecode.com/peli/32/12_2.png) [@peli](https://forum.makecode.com/u/peli)
#### Post date: [August 9, 2022, 6:15pm UTC](https://forum.makecode.com/t/using-jacdac-led-blocks-in-on-start/14642/2 "2022-08-09T18:15:15Z")

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Thanks for reporting this and opening a bug on github! I’m looking into this now.