<p>First, make sure that you have flashed your Uno to be an ICSP programmer.</p>
<p>Then you just connect up the SPI pins of the two boards.</p>
<p>The pins on the Uno that you must use, are these, circled in yellow (you can ignore the red circles):</p>
<p><a href="https://i.sstatic.net/MTfzC.jpg" rel="nofollow noreferrer" title="BigTreeTech board layout"><img src="https://i.sstatic.net/MTfzC.jpg" alt="Uno board layout" title="BigTreeTech board layout" /></a></p>
<p>The pin out is as follows:</p>
<p><a href="https://i.sstatic.net/etS4V.jpg" rel="nofollow noreferrer" title="Arduino Uno SPI pinout"><img src="https://i.sstatic.net/etS4V.jpg" alt="Arduino Uno SPI pinout" title="Arduino Uno SPI pinout" /></a></p>
<p>The pins on the BigTreeTech board are shown on the right hand edge/side of the board, half way down, where it says <strong>SPI1</strong>:</p>
<p><a href="https://i.sstatic.net/os9G0.png" rel="nofollow noreferrer" title="BigTreeTech board v1.2 layout"><img src="https://i.sstatic.net/os9G0.png" alt="BigTreeTech board v1.2 layout" title="BigTreeTech board v1.2 layout" /></a></p>
<p>The SPI pins on the v3 version of the board are still in a similar location, <em>but in a different order</em> (along with 2 other pins, that can be ignored):</p>
<p><a href="https://i.sstatic.net/HRqze.png" rel="nofollow noreferrer" title="BigTreeTech board v3 layout"><img src="https://i.sstatic.net/HRqze.png" alt="BigTreeTech board v3 layout" title="BigTreeTech board v3 layout" /></a></p>
<p>Connect these pins on the Uno, to the &quot;<em>like-for-like</em>&quot; pins on the BigTree - no crossing over of wires is required. So, connect:</p>
<ul>
<li>MOSI to MOSI</li>
<li>MISO to MISO</li>
<li>SCK to SCK</li>
<li>RESET to RESET</li>
<li>VCC to VCC</li>
<li>GND to GND</li>
</ul>
<p>On the V3 board ignore the additional <code>NSS</code> and <code>3.3V</code> pins on the SPI1 connector</p>
<hr />
<h3>References</h3>
<ul>
<li><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">BigTreeTech Board layout v.1.2</a></li>
<li><a href="https://github.com/bigtreetech/BIGTREETECH-SKR-mini-E3/blob/master/hardware/BTT%20SKR%20MINI%20E3%20V3.0/Hardware/BTT%20E3%20SKR%20MINI%20V3.0_PIN.pdf" rel="nofollow noreferrer">BigTreeTech Board layout v.3</a></li>
<li><a href="https://docs.arduino.cc/built-in-examples/arduino-isp/ArduinoISP" rel="nofollow noreferrer">Arduino as ISP and Arduino Bootloaders</a></li>
</ul>

CC BY-SA 4.0
2023-05-01T19:55:48.547Z
2023-05-01T21:11:05.907Z
2023-05-01T21:11:05.907Z
Greenonline
<p>I can't seem to find wiring diagrams anywhere, so I am asking here.</p>
<p>Which pins do I use to connect my Arduino Uno to my Bigtreetech board?</p>
<p>I am connecting the Arduino to use it as an ICSP programmer, so that you can flash the BigTreeTech board. I have a V3 board version.</p>

<bigtreetech><wiring><arduino>
How to connect Arduino Uno R3 to Bigtreetech SKR Mini E3 V3
Duncan McPherson
# How to connect Arduino Uno R3 to Bigtreetech SKR Mini E3 V3

(Asked by: username_0 on 2023-05-01)

I can't seem to find wiring diagrams anywhere, so I am asking here.

Which pins do I use to connect my Arduino Uno to my Bigtreetech board?

I am connecting the Arduino to use it as an ICSP programmer, so that you can flash the BigTreeTech board. I have a V3 board version.

**Tags:** bigtreetech, wiring, arduino

---

## 1 answers

### Answer by username_1 on 2023-05-01. Score: 2 | Accepted answer

First, make sure that you have flashed your Uno to be an ICSP programmer.

Then you just connect up the SPI pins of the two boards.

The pins on the Uno that you must use, are these, circled in yellow (you can ignore the red circles):

[![Uno board layout](https://i.sstatic.net/MTfzC.jpg "BigTreeTech board layout")](https://i.sstatic.net/MTfzC.jpg "BigTreeTech board layout")

The pin out is as follows:

[![Arduino Uno SPI pinout](https://i.sstatic.net/etS4V.jpg "Arduino Uno SPI pinout")](https://i.sstatic.net/etS4V.jpg "Arduino Uno SPI pinout")

The pins on the BigTreeTech board are shown on the right hand edge/side of the board, half way down, where it says **SPI1**:

[![BigTreeTech board v1.2 layout](https://i.sstatic.net/os9G0.png "BigTreeTech board v1.2 layout")](https://i.sstatic.net/os9G0.png "BigTreeTech board v1.2 layout")

The SPI pins on the v3 version of the board are still in a similar location, *but in a different order* (along with 2 other pins, that can be ignored):

[![BigTreeTech board v3 layout](https://i.sstatic.net/HRqze.png "BigTreeTech board v3 layout")](https://i.sstatic.net/HRqze.png "BigTreeTech board v3 layout")

Connect these pins on the Uno, to the "*like-for-like*" pins on the BigTree - no crossing over of wires is required. So, connect:

* MOSI to MOSI
* MISO to MISO
* SCK to SCK
* RESET to RESET
* VCC to VCC
* GND to GND

On the V3 board ignore the additional `NSS` and `3.3V` pins on the SPI1 connector

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### References

* [BigTreeTech Board layout v.1.2](https://github.com/bigtreetech/BIGTREETECH-SKR-mini-E3/blob/master/hardware/BTT%20SKR%20MINI%20E3%20V1.2/BTT%20SKR%20MINI%20E3%20V1.2PIN.pdf)
* [BigTreeTech Board layout v.3](https://github.com/bigtreetech/BIGTREETECH-SKR-mini-E3/blob/master/hardware/BTT%20SKR%20MINI%20E3%20V3.0/Hardware/BTT%20E3%20SKR%20MINI%20V3.0_PIN.pdf)
* [Arduino as ISP and Arduino Bootloaders](https://docs.arduino.cc/built-in-examples/arduino-isp/ArduinoISP)


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