# GPIO Allocation

The table below lists all ESP32 GPIOs used by the SLWF-09, their assigned functions, and the type of interface or peripheral they control.  
Pins marked with “\*” are only used when the corresponding **add-on module** (Ethernet or Microphone) is installed.  
The PoE add-on does not consume any GPIO pins.

<div class="_tableContainer_1rjym_1" id="bkmrk-type-function-gpio-b"><div class="_tableWrapper_1rjym_13 group flex w-fit flex-col-reverse" tabindex="-1"><table class="w-fit min-w-(--thread-content-width)" data-end="1976" data-start="446" style="width: 67.381%; height: 791px;"><thead data-end="500" data-start="446"><tr data-end="500" data-start="446" style="height: 29.7969px;"><th data-col-size="sm" data-end="461" data-start="446" style="width: 24.2744%; height: 29.7969px;">Type</th><th data-col-size="sm" data-end="492" data-start="461" style="width: 56.7282%; height: 29.7969px;">Function</th><th data-col-size="sm" data-end="500" data-start="492" style="width: 18.9974%; height: 29.7969px;">GPIO</th></tr></thead><tbody data-end="1976" data-start="556"><tr data-end="611" data-start="556" style="height: 29.7969px;"><td data-col-size="sm" data-end="571" data-start="556" style="width: 24.2744%; height: 29.7969px;">Boot/Prog</td><td data-col-size="sm" data-end="602" data-start="571" style="width: 56.7282%; height: 29.7969px;">Not exposed</td><td data-col-size="sm" data-end="611" data-start="602" style="width: 18.9974%; height: 29.7969px;">GPIO0</td></tr><tr data-end="667" data-start="612" style="height: 29.7969px;"><td data-col-size="sm" data-end="627" data-start="612" style="width: 24.2744%; height: 29.7969px;">LED</td><td data-col-size="sm" data-end="658" data-start="627" style="width: 56.7282%; height: 29.7969px;">On board LED</td><td data-col-size="sm" data-end="667" data-start="658" style="width: 18.9974%; height: 29.7969px;">GPIO2</td></tr><tr data-end="723" data-start="668" style="height: 29.7969px;"><td data-col-size="sm" data-end="683" data-start="668" style="width: 24.2744%; height: 29.7969px;">LED</td><td data-col-size="sm" data-end="714" data-start="683" style="width: 56.7282%; height: 29.7969px;">LED data output 1 (DATA)</td><td data-col-size="sm" data-end="723" data-start="714" style="width: 18.9974%; height: 29.7969px;">GPIO4</td></tr><tr data-end="780" data-start="724" style="height: 29.7969px;"><td data-col-size="sm" data-end="739" data-start="724" style="width: 24.2744%; height: 29.7969px;">LED</td><td data-col-size="sm" data-end="770" data-start="739" style="width: 56.7282%; height: 29.7969px;">LED data output 2 (for clocked LEDs)</td><td data-col-size="sm" data-end="780" data-start="770" style="width: 18.9974%; height: 29.7969px;">GPIO17</td></tr><tr data-end="836" data-start="781" style="height: 29.7969px;"><td data-col-size="sm" data-end="796" data-start="781" style="width: 24.2744%; height: 29.7969px;">I²C</td><td data-col-size="sm" data-end="827" data-start="796" style="width: 56.7282%; height: 29.7969px;">I²C SCL (expansion) (**10k pull up**)</td><td data-col-size="sm" data-end="836" data-start="827" style="width: 18.9974%; height: 29.7969px;">GPIO5</td></tr><tr data-end="893" data-start="837" style="height: 29.7969px;"><td data-col-size="sm" data-end="852" data-start="837" style="width: 24.2744%; height: 29.7969px;">I²C / Mic</td><td data-col-size="sm" data-end="883" data-start="852" style="width: 56.7282%; height: 29.7969px;">I²C SDA / Mic SCK\* (**10k pull up**)</td><td data-col-size="sm" data-end="893" data-start="883" style="width: 18.9974%; height: 29.7969px;">GPIO14</td></tr><tr data-end="950" data-start="894" style="height: 29.7969px;"><td data-col-size="sm" data-end="909" data-start="894" style="width: 24.2744%; height: 29.7969px;">Mic</td><td data-col-size="sm" data-end="940" data-start="909" style="width: 56.7282%; height: 29.7969px;">Mic WS\*</td><td data-col-size="sm" data-end="950" data-start="940" style="width: 18.9974%; height: 29.7969px;">GPIO15</td></tr><tr data-end="1007" data-start="951" style="height: 29.7969px;"><td data-col-size="sm" data-end="966" data-start="951" style="width: 24.2744%; height: 29.7969px;">Mic</td><td data-col-size="sm" data-end="997" data-start="966" style="width: 56.7282%; height: 29.7969px;">Mic SD\*</td><td data-col-size="sm" data-end="1007" data-start="997" style="width: 18.9974%; height: 29.7969px;">GPIO32</td></tr><tr data-end="1064" data-start="1008" style="height: 29.7969px;"><td data-col-size="sm" data-end="1023" data-start="1008" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1054" data-start="1023" style="width: 56.7282%; height: 29.7969px;">PHY RXER\*</td><td data-col-size="sm" data-end="1064" data-start="1054" style="width: 18.9974%; height: 29.7969px;">GPIO13</td></tr><tr data-end="1121" data-start="1065" style="height: 29.7969px;"><td data-col-size="sm" data-end="1080" data-start="1065" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1111" data-start="1080" style="width: 56.7282%; height: 29.7969px;">PHY Clock Enable / OSCEN\*</td><td data-col-size="sm" data-end="1121" data-start="1111" style="width: 18.9974%; height: 29.7969px;">GPIO16</td></tr><tr data-end="1178" data-start="1122" style="height: 29.7969px;"><td data-col-size="sm" data-end="1137" data-start="1122" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1168" data-start="1137" style="width: 56.7282%; height: 29.7969px;">MDIO\*</td><td data-col-size="sm" data-end="1178" data-start="1168" style="width: 18.9974%; height: 29.7969px;">GPIO18</td></tr><tr data-end="1235" data-start="1179" style="height: 29.7969px;"><td data-col-size="sm" data-end="1194" data-start="1179" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1225" data-start="1194" style="width: 56.7282%; height: 29.7969px;">TXD0\*</td><td data-col-size="sm" data-end="1235" data-start="1225" style="width: 18.9974%; height: 29.7969px;">GPIO19</td></tr><tr data-end="1292" data-start="1236" style="height: 29.7969px;"><td data-col-size="sm" data-end="1251" data-start="1236" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1282" data-start="1251" style="width: 56.7282%; height: 29.7969px;">TXEN\*</td><td data-col-size="sm" data-end="1292" data-start="1282" style="width: 18.9974%; height: 29.7969px;">GPIO21</td></tr><tr data-end="1349" data-start="1293" style="height: 29.7969px;"><td data-col-size="sm" data-end="1308" data-start="1293" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1339" data-start="1308" style="width: 56.7282%; height: 29.7969px;">TXD1\*</td><td data-col-size="sm" data-end="1349" data-start="1339" style="width: 18.9974%; height: 29.7969px;">GPIO22</td></tr><tr data-end="1406" data-start="1350" style="height: 29.7969px;"><td data-col-size="sm" data-end="1365" data-start="1350" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1396" data-start="1365" style="width: 56.7282%; height: 29.7969px;">MDC\*</td><td data-col-size="sm" data-end="1406" data-start="1396" style="width: 18.9974%; height: 29.7969px;">GPIO23</td></tr><tr data-end="1463" data-start="1407" style="height: 29.7969px;"><td data-col-size="sm" data-end="1422" data-start="1407" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1453" data-start="1422" style="width: 56.7282%; height: 29.7969px;">RXD0\*</td><td data-col-size="sm" data-end="1463" data-start="1453" style="width: 18.9974%; height: 29.7969px;">GPIO25</td></tr><tr data-end="1520" data-start="1464" style="height: 29.7969px;"><td data-col-size="sm" data-end="1479" data-start="1464" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1510" data-start="1479" style="width: 56.7282%; height: 29.7969px;">RXD1\*</td><td data-col-size="sm" data-end="1520" data-start="1510" style="width: 18.9974%; height: 29.7969px;">GPIO26</td></tr><tr data-end="1577" data-start="1521" style="height: 29.7969px;"><td data-col-size="sm" data-end="1536" data-start="1521" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1567" data-start="1536" style="width: 56.7282%; height: 29.7969px;">CRS\_DV\*</td><td data-col-size="sm" data-end="1577" data-start="1567" style="width: 18.9974%; height: 29.7969px;">GPIO27</td></tr><tr data-end="1634" data-start="1578" style="height: 29.7969px;"><td data-col-size="sm" data-end="1593" data-start="1578" style="width: 24.2744%; height: 29.7969px;">Relay</td><td data-col-size="sm" data-end="1624" data-start="1593" style="width: 56.7282%; height: 29.7969px;">LED power line control</td><td data-col-size="sm" data-end="1634" data-start="1624" style="width: 18.9974%; height: 29.7969px;">GPIO33</td></tr><tr data-end="1691" data-start="1635" style="height: 29.7969px;"><td data-col-size="sm" data-end="1650" data-start="1635" style="width: 24.2744%; height: 29.7969px;">Button</td><td data-col-size="sm" data-end="1681" data-start="1650" style="width: 56.7282%; height: 29.7969px;">Button 1</td><td data-col-size="sm" data-end="1691" data-start="1681" style="width: 18.9974%; height: 29.7969px;">GPIO34</td></tr><tr data-end="1748" data-start="1692" style="height: 29.7969px;"><td data-col-size="sm" data-end="1707" data-start="1692" style="width: 24.2744%; height: 29.7969px;">DIY1</td><td data-col-size="sm" data-end="1738" data-start="1707" style="width: 56.7282%; height: 29.7969px;">DIY input/output</td><td data-col-size="sm" data-end="1748" data-start="1738" style="width: 18.9974%; height: 29.7969px;">GPIO36</td></tr><tr data-end="1805" data-start="1749" style="height: 29.7969px;"><td data-col-size="sm" data-end="1764" data-start="1749" style="width: 24.2744%; height: 29.7969px;">Ethernet</td><td data-col-size="sm" data-end="1795" data-start="1764" style="width: 56.7282%; height: 29.7969px;">Ethernet detect\*</td><td data-col-size="sm" data-end="1805" data-start="1795" style="width: 18.9974%; height: 29.7969px;">GPIO37</td></tr><tr data-end="1862" data-start="1806" style="height: 29.7969px;"><td data-col-size="sm" data-end="1821" data-start="1806" style="width: 24.2744%; height: 29.7969px;">DIY2</td><td data-col-size="sm" data-end="1852" data-start="1821" style="width: 56.7282%; height: 29.7969px;">DIY input/output</td><td data-col-size="sm" data-end="1862" data-start="1852" style="width: 18.9974%; height: 29.7969px;">GPIO38</td></tr><tr data-end="1919" data-start="1863" style="height: 29.7969px;"><td data-col-size="sm" data-end="1878" data-start="1863" style="width: 24.2744%; height: 29.7969px;">Button</td><td data-col-size="sm" data-end="1909" data-start="1878" style="width: 56.7282%; height: 29.7969px;">Button 2</td><td data-col-size="sm" data-end="1919" data-start="1909" style="width: 18.9974%; height: 29.7969px;">GPIO39</td></tr><tr data-end="1976" data-start="1920" style="height: 29.7969px;"><td data-col-size="sm" data-end="1935" data-start="1920" style="width: 24.2744%; height: 29.7969px;">Reserved</td><td data-col-size="sm" data-end="1966" data-start="1935" style="width: 56.7282%; height: 29.7969px;">Not connected (NC)</td><td data-col-size="sm" data-end="1976" data-start="1966" style="width: 18.9974%; height: 29.7969px;">GPIO35</td></tr></tbody></table>

</div></div>[![image.png](https://smlight.tech/support/manuals/uploads/images/gallery/2025-10/scaled-1680-/image.png)](https://smlight.tech/support/manuals/uploads/images/gallery/2025-10/image.png)