Omega PoE Dock



  • @peanut I got the Ethernet jack LEDs working.
    relevant thread here

    The specific bit of device-tree magic was to add my new gpio-leds:

    gpio-leds {
    	compatible = "gpio-leds";
    	system_led: system {
    		gpios = <&gpio1 12 GPIO_ACTIVE_LOW>;
    	};
           user_led: user {
    		gpios = <&gpio0 0x11 GPIO_ACTIVE_LOW>;
    	};
           eth_y_led: eth_y_led {
    		gpios = <&gpio0 0x10 GPIO_ACTIVE_HIGH>;
    	};
           eth_g_led: eth_g_led {
    		gpios = <&gpio0 0x0F GPIO_ACTIVE_HIGH>;
    	};
    };
    

    Note that they're on GPIO0.

    And something like this:

    echo netdev > /sys/class/leds/eth_y_led/trigger
    echo eth0 >/sys/class/leds/eth_y_led/device_name
    echo "link tx rx" >/sys/class/leds/eth_y_led/mode
    echo 20 >/sys/class/leds/eth_y_led/interval
    

    That said, it wasn't really worth it :(

    After I got it working, I realized that the only thing it could tell me is that there were packets. The most important part of link lights is usually to know that there's link, but it's pretty unusual (but not impossible) to get Power over Ethernet without also getting, well, Ethernet. This means that on my PoE board, the Ethernet link light is only very slightly different than a power LED, which we already have. And until I get default values into the device tree, it doesn't come up until I turn it on from userspace anyways.

    Still, it's nice to know how to turn GPIOs into LEDs, allowing a wide range of triggers. If this thing were in a box, I might use those ethernal Ethernet link LEDs as a heartbeat, or as an disk activity indicator.



  • I am building a Hub that supports POE as well. The circuit I am using supports 12-48v DC (dont want to deal with diode rectifier for AC) POE injectors. I am actually using Ubiquity as one of the POE testers.

    You have a lot more passive components than I do. Mine only uses 12 BOM line items. (14) total. Maybe because my Ethernet Jack has the Harmonics built in. Either way, good work.



  • @brolly759 I'm curious to see your design - I think mine is a bit overkill.

    I opted for up to 15W power, and I wanted a 12V line, meaning I have a 3.3V, a 5V, and a 12V converter. I also wanted to do electrical isolation, as I think you're supposed to for IEEE 802.3af devices that can come into contact with a person. The electrical isolation means the giant flyback transformer, as well as optoisolation and the associated passives to (hopefully) filter the opto feedback loop.

    That said, yeah, it ends up being expensive. It's still working well though, and I think I'll get more boards assembled for my own use at some point.

    I've been impressed by how much cheaper the RJ45 jacks with integrated magnetics have gotten. There are even some (harder to find) with built-in rectifier diodes, which saves even more components.



  • I follow your project. It looks very well.



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