# ScrollPhat HD GPIO

**URL:** <https://forums.pimoroni.com/t/scrollphat-hd-gpio/13355>\
**Category:** Support\
**Created:** [March 20, 2020, 8:59pm UTC](https://forums.pimoroni.com/t/scrollphat-hd-gpio/13355 "2020-03-20T20:59:19Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![paulsocal](https://avatars.discourse-cdn.com/v4/letter/p/3d9bf3/32.png) [@paulsocal](https://forums.pimoroni.com/u/paulsocal)\
**Post date:** [March 20, 2020, 8:59pm UTC](https://forums.pimoroni.com/t/scrollphat-hd-gpio/13355/1 "2020-03-20T20:59:20Z")

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Hey all,

I just hooked up my Scroll Phat HD to my Raspberry PI zero and it was amazingly easy. I want to add a few more components to what I’m building. I want to add a relay switch and wanted to see if there are an free GPIO pins I can still use. Or does the board use all the PI pins.

Thanks in advance!  
Paul

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**Author:** ![neilman](https://avatars.discourse-cdn.com/v4/letter/n/6de8d8/32.png) [@neilman](https://forums.pimoroni.com/u/neilman)\
**Post date:** [March 20, 2020, 9:04pm UTC](https://forums.pimoroni.com/t/scrollphat-hd-gpio/13355/2 "2020-03-20T21:04:52Z")

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> [@paulsocal](#):
>
> Scroll Phat HD

Paul, if you look here…

> **[Scroll pHAT HD at Raspberry Pi GPIO Pinout](https://pinout.xyz/pinout/scroll_phat_hd#)**
>
> A 17 x 7 LED matrix

you’ll find your answer :-)

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**Author:** ![alphanumeric](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/alphanumeric/32/2729_2.png) [@alphanumeric](https://forums.pimoroni.com/u/alphanumeric)\
**Post date:** [March 20, 2020, 9:26pm UTC](https://forums.pimoroni.com/t/scrollphat-hd-gpio/13355/3 "2020-03-20T21:26:44Z")

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If you mount this on a stacking header you can put it between your Pi and pHat to get easy access to the GPIO.

> **[ProtoZero – Pimoroni Store](https://shop.pimoroni.com/products/protozero)**
>
> The ProtoZero is a prototyping board for the Raspberry Pi Zero, that also fits the A+, B+ and Pi2.

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**Author:** ![paulsocal](https://avatars.discourse-cdn.com/v4/letter/p/3d9bf3/32.png) [@paulsocal](https://forums.pimoroni.com/u/paulsocal)\
**Post date:** [March 20, 2020, 9:57pm UTC](https://forums.pimoroni.com/t/scrollphat-hd-gpio/13355/4 "2020-03-20T21:57:35Z")

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Ah! Exactly what I was looking for. So from my understanding of that diagram, its only using pins 2, 3, 5 & 9?

Thanks for your help @neilman

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**Author:** ![paulsocal](https://avatars.discourse-cdn.com/v4/letter/p/3d9bf3/32.png) [@paulsocal](https://forums.pimoroni.com/u/paulsocal)\
**Post date:** [March 20, 2020, 10:05pm UTC](https://forums.pimoroni.com/t/scrollphat-hd-gpio/13355/5 "2020-03-20T22:05:39Z")

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Nevermind, just tested those pins and they indeed are the ones

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**Author:** ![alphanumeric](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/alphanumeric/32/2729_2.png) [@alphanumeric](https://forums.pimoroni.com/u/alphanumeric)\
**Post date:** [March 20, 2020, 10:06pm UTC](https://forums.pimoroni.com/t/scrollphat-hd-gpio/13355/6 "2020-03-20T22:06:40Z")

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Thats is correct 2, 3, 5 & 9. 3 and 5 are i2c which is a shared bus. You can connect other i2c devices to those pins as long as no two devices share the same i2c address.  
The scroll phat uses 0x74: for the IS31FL3731