Power over Ethernet

The Compute Blade features support for PoE (802.3af), PoE+(802.3at), and PoE++(802.3bt).

Power Consumption

Power consumption will vary based on load, accessories connected, and the power requirements of any devices installed in the M.2 slot. During testing, a Compute Blade with a CM4 overclocked to 2GHz and a consumer NVMe SSD under load consumes ~7W. Normal operation may range from 3W to 17W depending on workload.

PoE+ Indicator

On the Compute Blade, GPIO23 is used to indicate the presence of PoE+ or PoE++. This could be used modify the behavior of the blade depending to the supplied power. There is an LED on the Blade with a + label indicating power state.

note

GPIO23 must be pulled up using the internal pull up.

LED Color	Description	GPIO 23	Power
Green	5 Volt present (PoE or USB)	HIGH	up to 15W
Orange	PoE+ or PoE++ present	LOW	up to 30W

Accessing the PoE+ Status in Software

These are example of how to get the GPIO23 state to determine the if PoE+ is present.

Python

import RPi.GPIO as GPIO
import time

# Define the GPIO pin number for the PoE indicator
POE_INDICATOR_GPIO = 23

# Set the GPIO mode to the BCM pin numbers
GPIO.setmode(GPIO.BCM)

# Set GPIO to an input and pull up the line
GPIO.setup(POE_INDICATOR_GPIO, GPIO.IN, pull_up_down=GPIO.PUD_UP)

try:
    # Read the state of the GPIO pin
    button_state = GPIO.input(POE_INDICATOR_GPIO)

    # Check if the pin is active (assuming active-high logic)
    if button_state == True:
        print("Powersource: PoE+ or PoE++")
    else:
        print("Powersource: PoE or USB Type-C")
except:
    GPIO.cleanup()

C

#include <stdio.h>
#include <wiringPi.h>

// Define the GPIO pin number for the PoE indicator
#define POE_INDICATOR_GPIO 23

int main(void) {
    // Initialize the wiringPi library
    if (wiringPiSetupGpio() == -1) {
        printf("wiringPi setup failed\n");
        return 1;
    }

    // Set the GPIO pin mode to input
    pinMode(POE_INDICATOR_GPIO, INPUT);

    // Read the state of the GPIO pin
    int poeIndicatorState = digitalRead(POE_INDICATOR_GPIO);

    // Check if the pin is active (assuming active-high logic)
    if (poeIndicatorState == HIGH) {
        printf("Powersource: PoE or USB Type-C\n");
    } else {
        printf("Powersource: PoE+ or PoE++\n");
    }

    return 0;
}

PoE Modules

Different Compute Blade revisions use different PoE modules. See the table below:

Version	PoE Module	Volts	Power Output (Peak)	PoE Compliance	Classification
v1.0	Silvertel Ag5405	5V	25.5W (30W)	IEEE 802.3af, 802.3at, 802.3bt	Type 2, Class 4