<p>You do not need to connect the red (+) wire of the endstops. The controller board uses a technique to ensure the signal is 3.3&nbsp;V or ground, see the top left schematics of <a href="https://github.com/bigtreetech/BIGTREETECH-SKR-mini-E3/blob/master/hardware/BTT%20SKR%20MINI%20E3%20V1.2/BTT%20SKR%20mini%20E3%20V1.2sch.pdf" rel="nofollow noreferrer">this link</a> (will insert an image later!). Specifics about this technology is found <a href="https://en.m.wikipedia.org/wiki/Pull-up_resistor" rel="nofollow noreferrer">here</a> and is explained as using a pull up resistor.</p>

<p>What happens is that the signal is always reported as triggered, unless the endstop connects the signal wire to ground.</p>

<p><a href="https://github.com/bigtreetech/BIGTREETECH-SKR-mini-E3/blob/master/hardware/BTT%20SKR%20MINI%20E3%20V1.2/BTT%20SKR%20MINI%20E3%20V1.2PIN.pdf" rel="nofollow noreferrer">This link</a> shows that only ground and signal are required (will insert an image later!).</p>

CC BY-SA 4.0
2020-04-28T23:40:26.287Z
2020-04-28T23:40:26.287Z
0scar
<p>I recently purchased a BigTreeTech mini e3 V1.2 controller for my custom built 3D printer (as opposed to an pre-purchased ender 3). In doing so, I ran into the problem that the endstops I have been using have three wires: Power, Ground, and signal. The mini e3 V1.2 that I purchased uses endstop connections that only have two pins. This can be seen in the schematic below on the bottom right of the controller. I don't know where to buy endstops that only have two pins and have not been able to find anything online. If anybody knows where these can be bought or how the 3 pinned endstops are supposed to be wired up it would be much appreciated.</p>

<p><a href="https://i.sstatic.net/p2RXe.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/p2RXe.png" alt="enter image description here"></a></p>

<wiring><endstop><skr-mini-e3><bigtreetech>
BigTreeTech mini e3 V1.2 endstop installation
Jack Hasselbring
# BigTreeTech mini e3 V1.2 endstop installation

(Asked by: username_0 on 2020-04-28)

I recently purchased a BigTreeTech mini e3 V1.2 controller for my custom built 3D printer (as opposed to an pre-purchased ender 3). In doing so, I ran into the problem that the endstops I have been using have three wires: Power, Ground, and signal. The mini e3 V1.2 that I purchased uses endstop connections that only have two pins. This can be seen in the schematic below on the bottom right of the controller. I don't know where to buy endstops that only have two pins and have not been able to find anything online. If anybody knows where these can be bought or how the 3 pinned endstops are supposed to be wired up it would be much appreciated.

[![enter image description here](https://i.sstatic.net/p2RXe.png)](https://i.sstatic.net/p2RXe.png)

**Tags:** wiring, endstop, skr-mini-e3, bigtreetech


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## 1 answers

### Answer by username_1 on 2020-04-28. Score: 1 | Accepted answer

You do not need to connect the red (+) wire of the endstops. The controller board uses a technique to ensure the signal is 3.3 V or ground, see the top left schematics of [this link](https://github.com/bigtreetech/BIGTREETECH-SKR-mini-E3/blob/master/hardware/BTT%20SKR%20MINI%20E3%20V1.2/BTT%20SKR%20mini%20E3%20V1.2sch.pdf) (will insert an image later!). Specifics about this technology is found [here](https://en.m.wikipedia.org/wiki/Pull-up_resistor) and is explained as using a pull up resistor.

What happens is that the signal is always reported as triggered, unless the endstop connects the signal wire to ground.

[This link](https://github.com/bigtreetech/BIGTREETECH-SKR-mini-E3/blob/master/hardware/BTT%20SKR%20MINI%20E3%20V1.2/BTT%20SKR%20MINI%20E3%20V1.2PIN.pdf) shows that only ground and signal are required (will insert an image later!).


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