14:39 <re_irc> <firefrommoonlight> korken89's Ethernet lib suggestion got me thinking... What do y'all generally use Ethernet for on MCUs? Can you plug it into a router or ESP chip, then send and Rx TCP messages?

14:40 <re_irc> <firefrommoonlight> Might be fun to implement a "hardware" port scanner for fun

14:40 <re_irc> <firefrommoonlight> And learning

14:48 <re_irc> <ryan-summers> Quartiq uses ethernet for telemetry and run-time settings configurations via MQTT. It's also used for livestreaming high frequency sampling data

14:48 <re_irc> <ryan-summers> Livestreaming lets us build an oscilloscope on the web browser, but the data comes from the ethernet interface to the MCU, since it's got a high bandwidth

14:49 <re_irc> <ryan-summers> Also use it for low-frequency telemetry from the device

14:49 <re_irc> <firefrommoonlight> Nice!

14:49 <re_irc> <ryan-summers> It integrates nicely with e.g. telegraf and other dashboards so you can see long-term (e.g. ~30 days) measurements of device info, like temperature

14:50 <re_irc> <firefrommoonlight> That's cool

14:50 <re_irc> <firefrommoonlight> The PC/MCU interactions I've done so far have all been USB/serial

14:52 <re_irc> <ryan-summers> Anything more than a serial connection tends to become a lot more complex because of the need for state management, protocols, and timing constraints. Thankfully, there's solutions like Smoltcp to handle the complexity

14:53 <re_irc> <adamgreig> at work we have a lot of ethernet embedded devices for data acquisition, control systems, stuff like that, for hobby projects i also like it for always-on background stuff that wants to send data while my computer's off, like my weird mains frequency logger and stuff

14:53 <re_irc> <adamgreig> and yea, you plug it in to the wired network as usual and send/receive data

14:54 <re_irc> <ryan-summers> If you have PoE capable device, the ethernet cable doubles as your power supply

14:54 <re_irc> <adamgreig> yea, super handy

14:54 <re_irc> <ryan-summers> Which is nice to eliminate all the cabling

14:54 <re_irc> <ryan-summers> Although PoE is pretty complex circuit-wise

14:54 <re_irc> <adamgreig> and you can do time sync over ethernet too if your mcu supports some sort of timestamping (like all stm32s)

14:54 <re_irc> <adamgreig> eh, it's not so bad? you need poe compatible magnetics/magjack, a poe client chip which is just a soic8, and maybe some passives?

14:54 <re_irc> <adamgreig> i guess it depends on how you do the isolation

14:54 <re_irc> <adamgreig> we use an off the shelf dcdc brick with 3kV isolation which suffices

14:55 <re_irc> <ryan-summers> Yeah, but gotta make sure you connect it all up right, and not be misled by component symbols in your hardware libs ;)

14:55 <re_irc> <adamgreig> hah, sure, there's that

14:55 <re_irc> <Catherine> and a buck, right?

14:55 <re_irc> <ryan-summers> Fried a few PHYs because of improperly spec'd protection diodes

14:55 <re_irc> <adamgreig> if the PoE-powered device is itself isolated and has no electrical connections, you can just use the -48V DC from the PoE, but in most cases you'll need an isolated DCDC of some description

14:56 <re_irc> <ryan-summers> But yeah, PoE supporting switches are generally also more expensive

14:56 <re_irc> <Catherine> i remember looking at isolated poe converter topologies and finding a lot of flybacks, which seemed like a pain

14:56 <re_irc> <adamgreig> yea, it's really common to have an isolated flyback topology, but i just use a traco power isolated dc/dc converter which is just power in one side and power out the other

14:57 <re_irc> <adamgreig> https://www.ael.co.uk/images/HTX_DAQ.jpg is an old work project, having poe saves sooooo much wiring and faff and power supplies, for the sake of one or two slightly more expensive switches

14:57 <re_irc> <Catherine> where do you even get a flyback transformer besides "winding one"

14:57 <re_irc> https://github.com/sinara-hw/Stabilizer/releases/tag/v1.3.2

14:57 <re_irc> <ryan-summers> Stabilizer's got a PoE reference design if you're curious:

14:57 <re_irc> Pretty sure it's taken from the STM32H7 ref designs

14:57 <re_irc> <Catherine> they aren't exactly sold at digikey

14:57 <re_irc> <adamgreig> that was from before I implemented the PTP sync so still had coax, but these days the sync can go over the ethernet too

14:57 <re_irc> <adamgreig> there are still some at digikey I think! I had a weird one a while back for my diy 400v smps

14:58 <re_irc> <ryan-summers> I think they just buy a pre-made converter that takes in the PoE and outputs 12V

14:58 <re_irc> <Catherine> lol sinara

14:58 <re_irc> <Catherine> didn't expect to encounter that again

14:58 <re_irc> <ryan-summers> Ew, yeah that module is 17 EUR: https://eu.mouser.com/ProductDetail/Silvertel/Ag5300?qs=OlC7AqGiEDkqNoWY4wzXEQ%3D%3D

14:59 <re_irc> <adamgreig> https://www.mouser.co.uk/ProductDetail/Coilcraft/GA3459-BL?qs=ZYnrCdKdyecGrzi6ofbvIw%3D%3D

14:59 <re_irc> <adamgreig> not really suitable for PoE though, heh

14:59 <re_irc> <Catherine> yes, you can get _some_ transformers from the usual retailers

14:59 <re_irc> <Catherine> even some flybacks, i think! but usually not the kind you could use for PoE

15:00 <re_irc> <Catherine> oh, hm https://www.mouser.co.uk/new/coilcraft/coilcraft-high-power-poe-transformers/

15:00 <re_irc> <Catherine> that wasn't there when i looked! from 2019, it seems

15:02 <re_irc> <adamgreig> you can get pretty decent amounts of power out of PoE+ and PoE++ now too, like 70W

15:03 <re_irc> <K900> Wow they actually have a lot

15:03 <re_irc> <K900> https://www.coilcraft.com/en-us/products/transformers/power-transformers/power-over-ethernet/

15:03 <re_irc> <K900> Goes up to 120W, wow

15:03 <re_irc> <K900> (though that's not a flyback)

15:05 <re_irc> <adamgreig> £7 from digikey for like https://www.digikey.co.uk/en/products/detail/traco-power/TMR-1-4811/9383380 that will do 48V PoE in, isolated 5V out, saves such a ton of circuitry and smps design

15:05 <re_irc> <adamgreig> obviously higher power and voltages and such available

15:06 <re_irc> <K900> Now I'm trying to think about something I can use PoE for

15:06 <re_irc> <ryan-summers> Anywhere you've got ethernet, just slap one of those on instead and you no longer need a power source ;)

15:06 <re_irc> <K900> Yeah the problem is I have exactly 1 (one) Ethernet cable

15:06 <re_irc> <K900> And it runs from my switch to my PC

15:07 <re_irc> <K900> And I don't think I can power my PC off PoE (though that sounds like a fun cursed project)

15:07 <re_irc> <adamgreig> you can get some nice desktop PoE switches, like netgear gs308p or 305p

15:08 <re_irc> <K900> The switch actually does PoE already, it was supposed to connect to the building's CCTV system

15:08 <re_irc> <adamgreig> but yea, if you aren't already using ethernet for data on your embedded device, doing poe just for power probably doesn't make much sense

15:08 <re_irc> <K900> Then they scrapped the CCTV system

17:27 <re_irc> <James Munns> Olimex used to have a 10eur poe extractpr

17:27 <re_irc> <James Munns> * power extractor

17:28 <re_irc> <James Munns> But some cisco switches would get angery about it, so I guess I wouldn’t recommend it

18:39 <re_irc> <korken89> firefrommoonlight: In our case we want to have low latency with reliable communication for a huge IOT system, and as icing on the cake time synchronize all nodes via PTP

19:00 <re_irc> <firefrommoonlight> Sweet