# Pin EXP2\_1 is an alias for PA6

**URL:** <https://klipper.discourse.group/t/pin-exp2-1-is-an-alias-for-pa6/2133>\
**Category:** General Discussion\
**Created:** [February 22, 2022, 10:44pm UTC](https://klipper.discourse.group/t/pin-exp2-1-is-an-alias-for-pa6/2133 "2022-02-22T22:44:35Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Anthropos](https://avatars.discourse-cdn.com/v4/letter/a/c68b51/32.png) [@Anthropos](https://klipper.discourse.group/u/Anthropos)\
**Post date:** [February 22, 2022, 10:44pm UTC](https://klipper.discourse.group/t/pin-exp2-1-is-an-alias-for-pa6/2133/1 "2022-02-22T22:44:35Z")

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Hi,  
My first experience with Klipper , and my first own build of a printer.  
My MCU is BTT Octopus Pro. My Display is fystec mini.  
in my config i use the section [board\_pins] like every referenz i found. i receive the error: pin EXP2\_1 is an alias for PA6  
The klipperlog referenz the error to pins.py line 46.

(File “/home/pi/klipper/klippy/pins.py”, line 46, in pin\_fixup  
name, self.active\_pins[pin\_id]))  
error: pin EXP2\_1 is an alias for PA6)

Can i edit this file on my pi to cheat?

My speedy Solution!

[board\_pins]  
aliases:  
# EXP1 header  
EXP1\_1=PE8, EXP1\_2=PE7,  
EXP1\_3=PE9, EXP1\_4=PE10,  
EXP1\_5=PE12, EXP1\_6=PE13, # Slot in the socket on this side  
EXP1\_7=PE14, EXP1\_8=PE15,  
EXP1\_9=, EXP1\_10=\<5V\>,

```
# EXP2 header
#EXP2_1=PA6, EXP2_2=PA5,
EXP2_3=PB1, EXP2_4=PA4,
EXP2_5=PB2, #EXP2_6=PA7, # Slot in the socket on this side
EXP2_7=PC15, EXP2_8=<RST>,
EXP2_9=<GND>, EXP2_10=<5V>

```

[display]

## mini12864 LCD Display

lcd\_type: uc1701  
cs\_pin: PE9  
a0\_pin: EXP1\_4  
rst\_pin: EXP1\_5  
encoder\_pins: ^EXP2\_5, ^EXP2\_3  
click\_pin: ^!EXP1\_2  
contrast: 63  
spi\_software\_miso\_pin: PA6  
spi\_software\_mosi\_pin: PA7  
spi\_software\_sclk\_pin: PA5

Thanks for reading

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<div class="post-metadata">

**Author:** ![Sineos](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/sineos/32/18_2.png) [@Sineos](https://klipper.discourse.group/u/Sineos)\
**Post date:** [February 23, 2022, 7:37am UTC](https://klipper.discourse.group/t/pin-exp2-1-is-an-alias-for-pa6/2133/2 "2022-02-23T07:37:16Z")

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Please post your klippy.log showing the error.

Edit: Such an error can occur, e.g. if you create double aliases: `ALIAS1 = PA6` and then `ALIAS2 = ALIAS1`  
or similar configurations where you create references that are not supported.

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<div class="post-metadata">

**Author:** ![Anthropos](https://avatars.discourse-cdn.com/v4/letter/a/c68b51/32.png) [@Anthropos](https://klipper.discourse.group/u/Anthropos)\
**Post date:** [February 23, 2022, 4:46pm UTC](https://klipper.discourse.group/t/pin-exp2-1-is-an-alias-for-pa6/2133/3 "2022-02-23T16:46:52Z")

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i dont found the logfile yet.  
i copied only the line with the error, and the line before in the opening.  
Now it works fine without alias the SPI pins. I reached the status of my projekt: heaters heating,kinematics move inlucive gantry adjustment.  
now i have to learn how do make my silent stepper silent 😉 (TMC5160)

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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:** [August 19, 2025, 12:46pm UTC](https://klipper.discourse.group/t/pin-exp2-1-is-an-alias-for-pa6/2133/4 "2025-08-19T12:46:06Z")

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