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PoE management

On RTL8380 and RTL8390 switches based on Realtek's development boards, power over ethernet is usually not managed directly by the SoC itself, but by an intermediate microcontroller. This microcontroller in turn talks to a PoE power sourcing equipment (PSE) controller chip. The Realtek platform supports both a Broadcom based, and a Microsemi based implementation. A daemon running on the OS will poll the controller to manage the PoE ports and inform about their status.

The PSE controllers will always be in the PoE power domain, which needs to be isolated from the SoC to protect it from external PoE faults. This means that the PoE controller will talk to either the SoC or PSE controller through a pair of optocouplers or isolators. Be aware of this when probing the control signals on the PoE hardware.

Vendor Device SoC Management IC PSE controller PoE FW version PoE standard support
Cisco SG220-26P RTL8382M Microsemi PD69100 PD69108 (?) n/a 802.3at
D-Link DGS-1210-10P F1 RTL8380M Nuvoton M0516 (?) BMC59121 802.3at
Netgear GS110TPP v1 RTL8380M Nuvoton M0516 BCM59121 802.3at
Netgear GS710TUP Nuvoton M0518 BMC59121 ×2 802.3bt
Netgear GS728TP v2 RTL8391M Nuvoton M0516 BCM59121 ×3 802.3at
TP-Link T1600G-52PS RTL8393 - TI TPS23861PW ×12 n/a 802.3at
Trendnet TPE-1620WS RTL8382M Nuvoton M0516LDE BCM59121 ×2 802.3at
Zyxel GS1900-10HP RTL8380M STM 32F100 BCM59121 (BCM59121), (BCM59101) 802.3at
Zyxel GS1920-24HP STM 32F100 BMC59111 ×6 802.3at

On the Broadcom platform, an intermediate microcontroller is used to managed a Broadcom PSE controller, like the BCM59121. Although more than one microcontroller type is used over different products, they all appear to use the same serial protocol. The high level control and status commands between the microcontroller and SoC use the SoC's secondary UART. The UART connection between the SoC and microcontroller typically uses a 19200 baud, 8n1 connection. Communication between the microcontroller and the Broadcom chip uses Broadcom Serial Control (BSC), an I2C dialect.

See Broadcom PoE control protocol for more details.

Like the Broadcom platform, the Microsemi PoE platform also uses a combination of a SoC-PSE bridge as controller, and PSE management ICs to control the power to the PoE devices.


Until now, only one switch series was based TI's PSE controllers. These can be controlled directly by the SoC, or (according to TI's product pages) by an intermediate MCU.

In order to use PoE, you will need to use the rtl83xx-poe package which is currently only available from blogic's staging tree:;a=tree;f=package/rtl83xx-poe;hb=2540faec92abf8f5e52eae0e77bfbdb47457252d

Either compile the package separately and install it on the switch after booting up OpenWrt, or copy over the files in the files sub-directory over into the base-files directory of your OpenWrt git repository from which you build the switch firmware.

Information on how to configure is here:

  • software/poe_management.1614604407.txt.gz
  • Last modified: 2021/03/01 13:13
  • by pepe2k