# V1.1.5 pin 27 and 29 **URL:** \ **Category:** General Discussion\ **Created:** [May 22, 2025, 3:21am UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547 "2025-05-22T03:21:26Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![JJS12KMA](https://avatars.discourse-cdn.com/v4/letter/j/3da27b/32.png) [@JJS12KMA](https://klipper.discourse.group/u/JJS12KMA)\ **Post date:** [May 22, 2025, 3:21am UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/1 "2025-05-22T03:21:26Z")
### Basic Information: Printer Model: Ender 3 v1 MCU / Printerboard: v1.1.5 Host / SBC: RPI 2W klippy.log ### Describe your issue: No issue using the board flashed with Klipper via serial. Wanting to add additional runout sensors on pin 27 and 29 if possible. I only know how to define the pins in Marlin using the native names/aliases. Does anyone know how to define these in Klipper? Sorry I am new to all this coming from the Marlin world… Thank you in advance! [klippy.log](https://klipper.discourse.group/uploads/short-url/j0LiDinXaBtLv9rp9CPDmWbN6oJ.log) (25.9 KB) ---
**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:** [May 22, 2025, 6:07am UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/2 "2025-05-22T06:07:25Z")
See [Configuration reference - Klipper documentation](https://www.klipper3d.org/Config_Reference.html#filament_switch_sensor) and [How-To Ask for Help](https://klipper.discourse.group/t/how-to-ask-for-help/6327) ---
**Author:** ![JJS12KMA](https://avatars.discourse-cdn.com/v4/letter/j/3da27b/32.png) [@JJS12KMA](https://klipper.discourse.group/u/JJS12KMA)\ **Post date:** [May 22, 2025, 12:05pm UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/3 "2025-05-22T12:05:21Z")
Klippy.log added ---
**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:** [May 22, 2025, 4:13pm UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/4 "2025-05-22T16:13:51Z")
As shown in the posted link: Define any number of sensors similar to the one you already have, but with a different name. ---
**Author:** ![JJS12KMA](https://avatars.discourse-cdn.com/v4/letter/j/3da27b/32.png) [@JJS12KMA](https://klipper.discourse.group/u/JJS12KMA)\ **Post date:** [May 22, 2025, 4:27pm UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/5 "2025-05-22T16:27:42Z")
Sorry, I think my question was written poorly. What I am looking for is the pin 27 and 29 identification to define it as a sensor. Like where the endstop for X is PC2 and Y is PC3. Do 27 and 29 have such an identification to use in Klipper? I could be missing something; sleep has not been kind to me the last few weeks ☹ ---
**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:** [May 22, 2025, 6:40pm UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/6 "2025-05-22T18:40:29Z")
I’m not sure that I can meaningfully support this, as the available information on this board is pretty scarce. > [@JJS12KMA](#): > > Do 27 and 29 have such an identification to use in Klipper? If you are referring to the ATmega1284P pin numbering, here are the corresponding pin designations as used in Klipper: - 27 → PA3 - 29 → PA5 ---
**Author:** ![JJS12KMA](https://avatars.discourse-cdn.com/v4/letter/j/3da27b/32.png) [@JJS12KMA](https://klipper.discourse.group/u/JJS12KMA)\ **Post date:** [May 22, 2025, 9:07pm UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/7 "2025-05-22T21:07:39Z")
I didn’t think to look at a ATmega breakout, is that what you used? ☹ ---
**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:** [May 23, 2025, 12:38pm UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/8 "2025-05-23T12:38:26Z")
> [@JJS12KMA](#): > > Printerboard: v1.1.5 You find infos here: ![fc417b8653c337061786ed854c36b1f3dbdfa7ef](https://global.discourse-cdn.com/free1/uploads/klipper/original/3X/f/c/fc417b8653c337061786ed854c36b1f3dbdfa7ef.jpeg) ---
**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:** [May 23, 2025, 12:42pm UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/9 "2025-05-23T12:42:12Z")
> [@JJS12KMA](#): > > I didn’t think to look at a ATmega breakout, is that what you used? ☹ Exactly. As shown by @EddyMI3D ---
**Author:** ![JJS12KMA](https://avatars.discourse-cdn.com/v4/letter/j/3da27b/32.png) [@JJS12KMA](https://klipper.discourse.group/u/JJS12KMA)\ **Post date:** [May 23, 2025, 8:03pm UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/10 "2025-05-23T20:03:10Z")
Thank you both for your time and help! ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\ **Post date:** [July 22, 2025, 8:03pm UTC](https://klipper.discourse.group/t/v1-1-5-pin-27-and-29/23547/11 "2025-07-22T20:03:23Z")
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