# Externel MCU pin polarity

**URL:** <https://klipper.discourse.group/t/externel-mcu-pin-polarity/6698>\
**Category:** General Discussion\
**Created:** [February 16, 2023, 7:46am UTC](https://klipper.discourse.group/t/externel-mcu-pin-polarity/6698 "2023-02-16T07:46:18Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![sqrtmo](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@sqrtmo](https://klipper.discourse.group/u/sqrtmo)\
**Post date:** [February 16, 2023, 7:46am UTC](https://klipper.discourse.group/t/externel-mcu-pin-polarity/6698/1 "2023-02-16T07:46:18Z")

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Hello,

I am making a printer head PCB with RP2040 MCU and TMC2130 driver. The problem is that I am getting error when try to invert the driver cs pin polarity.  
My topic is related to this one: [Syntax error on Multi MCU pin with reverse polarity (!) · Issue #161 · Klipper3d/klipper · GitHub](https://github.com/Klipper3d/klipper/issues/161)

So when I try  
cs\_pin: !head0:gpio18  
I am getting  
Unknown pin chip name ‘!head0’

I can not find the right way to do that in the documentation.  
Can anyone help?

Thanks in advance!

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**Author:** ![EddyMI3D](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/eddymi3d/32/1981_2.png) [@EddyMI3D](https://klipper.discourse.group/u/EddyMI3D)\
**Post date:** [February 16, 2023, 7:56am UTC](https://klipper.discourse.group/t/externel-mcu-pin-polarity/6698/2 "2023-02-16T07:56:54Z")

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Hello @sqrtmo !

Please note the use of the Configs subforum:

![Configs](https://global.discourse-cdn.com/free1/uploads/klipper/original/2X/f/fe12f5b1ef0beb727309bb23afc90e4e8264084d.png)

Please share the klippy.log file in your next post

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**Author:** ![Royce](https://avatars.discourse-cdn.com/v4/letter/r/b5ac83/32.png) [@Royce](https://klipper.discourse.group/u/Royce)\
**Post date:** [February 16, 2023, 9:49am UTC](https://klipper.discourse.group/t/externel-mcu-pin-polarity/6698/3 "2023-02-16T09:49:54Z")

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> [@sqrtmo](#):
>
> cs\_pin: !head0:gpio18

Did you try

```auto
cs_pin: head0:!gpio18

```

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<div class="post-metadata">

**Author:** ![sqrtmo](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@sqrtmo](https://klipper.discourse.group/u/sqrtmo)\
**Post date:** [February 16, 2023, 9:50am UTC](https://klipper.discourse.group/t/externel-mcu-pin-polarity/6698/4 "2023-02-16T09:50:59Z")

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Yep and I am getting error as well

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<div class="post-metadata">

**Author:** ![sqrtmo](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@sqrtmo](https://klipper.discourse.group/u/sqrtmo)\
**Post date:** [February 16, 2023, 4:02pm UTC](https://klipper.discourse.group/t/externel-mcu-pin-polarity/6698/5 "2023-02-16T16:02:21Z")

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Attaching my log file  
[klippy.log](https://klipper.discourse.group/uploads/short-url/jj6NoV2OBYjEZX5MHOTi5xoDlio.log) (1.4 MB)

my Klipper version is: v0.11.0-110-gaca0c71a

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<div class="post-metadata">

**Author:** ![EddyMI3D](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/eddymi3d/32/1981_2.png) [@EddyMI3D](https://klipper.discourse.group/u/EddyMI3D)\
**Post date:** [April 28, 2024, 9:35am UTC](https://klipper.discourse.group/t/externel-mcu-pin-polarity/6698/6 "2024-04-28T09:35:06Z")

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