Power over Ethernet HAT (B) for Raspberry Pi 3B+/4B and 802.3af PoE network

The PoE HAT (B) is an 802.3af-compliant Power over Ethernet accessory for Raspberry Pi 3B+ and 4B. Provide both network connection and power supply through a single Ethernet cable – no separate power adapter needed when used with compatible PoE switches or injectors.

This HAT includes a 0.91" OLED display for real-time monitoring of processor temperature, IP address, and fan status. The onboard cooling fan can run automatically on power-up or be controlled programmatically via the included PCF8574 I/O expander.

Key Features

• 802.3af PoE Compliant – Power and network in one cable
• 0.91" OLED Display – Shows temperature, IP address, and fan status
• Cooling Fan – Auto or programmable control via switch
• Isolated SMPS – Fully isolated switched-mode power supply
• Stackable Header – 40-pin GPIO passthrough for additional HATs
• I/O Expander – PCF8574 provides extra GPIO pins (P1-P7)

Specifications

• PoE Input: 37V - 57V DC
• Power Output: 5V 2.5A DC
• Network Standard: 802.3af PoE
• OLED Size: 0.91" (128×32 pixels, white)
• OLED Driver: SSD1306
• I/O Expander: PCF8574 (I2C)
• Compatibility: Raspberry Pi 3B+, 4B
• Dimensions: 56.5mm × 65mm

Ideal For

• Network closet and server room deployments
• Remote monitoring stations
• Clean installations with single-cable setup
• Headless Raspberry Pi configurations

Resources

• Waveshare Wiki