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.
| Type | Function | GPIO |
|---|---|---|
| Boot/Prog | BOOT mode | GPIO0 |
| LED | LED1 control | GPIO2 |
| LED | LED data output (DATA) | GPIO4 |
| LED | LED clock (for clocked LEDs) | GPIO17 |
| I²C | I²C SCL (expansion) | GPIO5 |
| I²C / Mic | I²C SDA / Mic SCK* | GPIO14 |
| Mic | Mic WS* | GPIO15 |
| Mic | Mic SD* | GPIO32 |
| Ethernet | PHY RXER* | GPIO13 |
| Ethernet | PHY Clock Enable / OSCEN* | GPIO16 |
| Ethernet | MDIO* | GPIO18 |
| Ethernet | TXD0* | GPIO19 |
| Ethernet | TXEN* | GPIO21 |
| Ethernet | TXD1* | GPIO22 |
| Ethernet | MDC* | GPIO23 |
| Ethernet | RXD0* | GPIO25 |
| Ethernet | RXD1* | GPIO26 |
| Ethernet | CRS_DV* | GPIO27 |
| Relay | LED power line relay control | GPIO33 |
| Button | External button B2 | GPIO34 |
| DIY1 | Voltage sense/expansion | GPIO36 |
| Ethernet | Ethernet detect* | GPIO37 |
| DIY2 | Output / MOSFET control | GPIO38 |
| Button | External button B1 | GPIO39 |
| Reserved | Not connected (NC) | GPIO35 |