[HN Gopher] Hacker mods an M1 Mac mini to receive power over Eth... ___________________________________________________________________ Hacker mods an M1 Mac mini to receive power over Ethernet instead of AC Author : nrsapt Score : 124 points Date : 2023-08-01 19:54 UTC (3 hours ago) (HTM) web link (www.inferse.com) (TXT) w3m dump (www.inferse.com) | [deleted] | bgentry wrote: | The actual source referenced by the article appears to be this | tweet thread: | https://twitter.com/Merocle/status/1686093369322176512 | jeffbee wrote: | This seems to simply ignore the max continuous power rating of | 150W. The mini can output 15W on each thunderbolt port and | another 15W on its two USB ports, which is already nearly the | limit of 51W assured to each PoE++ endpoint, not even counting | the mini's own requirements. | JoeAltmaier wrote: | PoE is a mature technology. Curious that laptops have not been on | board. | contingencies wrote: | Historic energy consumption is probably higher than classically | POE supported. | | Also, any length of POE run gets voltage drop, and POE switches | and injectors often have tedious modal configuration based upon | length of run and are designed with non-standard limitations | such as maximum draw limits shared across multiple ports, which | in aggregate will cause no end of issues. For verification, ask | any experienced CCTV installer. These are exactly the sort of | issues that cause users to take products back to their | distributors. | | So it's a case of "works in theory, PITA in reality, probable | support and brand image impact huge, resulting priority zero". | JoeAltmaier wrote: | It's really popular in factories etc, because it reduces | cable runs I guess. | clintonb wrote: | An electrical outlet or USB-C connection is more readily | available to me than an Ethernet port with POE. Laptops aren't | onboard because the problem of powering laptops is largely | solved. Also...not many laptops have Ethernet ports. | asadhaider wrote: | Site's getting hugged to death by HN possibly, cached link to | article here- | https://web.archive.org/web/20230801195510/https://www.infer... | [deleted] | hhh wrote: | Merocle is also the creator of the Raspberry Pi Blade. | | https://www.kickstarter.com/projects/uptimelab/compute-blade | disillusioned wrote: | Having inadvertently plugged a 24v passive PoE live connection | into an old 2012 Mac Mini and immediately frying it, this is | welcome news! | mmastrac wrote: | I thought most modern devices had isolation! | somat wrote: | Note that there are real 48v 802.3af/at power over ethernet | devices where the power source has to assert that the power | drain wants the power before it powers up and fake "passive" | 24v systems where the line is always energized. probably | where the GP got the injector from. | | My personal involvement on this was several years ago when I | was going to buy several unifi access points. It turns out | you have to be careful because many of the models advertise | as being POE but in reality are jank 24v passive systems. I | have not kept up with the current unifi lineup but at the | time you had to make sure to get the "AC Pro" to have real | 802.3af compatibility. | mmastrac wrote: | I have a load of Unifi stuff here and it all supports | active PoE, but works just fine with passive. The PoE | outputs all autonegotiate. | progbits wrote: | Indeed, surprising. | | From IEEE 802.3 (revision 2012), section "32.6 PMA electrical | specifications": | | > The PHY shall provide electrical isolation between the DTE | or repeater circuits, including frame ground and all MDI | leads. | | > This electrical separation shall withstand at least one of | the following electrical strength tests: > [...] | | > b) 2250 Vdc for 60 s, [...] | | Non-compliant Ethernet PHY? | evadne wrote: | Passive PoE is always on | | Active PoE is negotiated with handshake | jcrawfordor wrote: | Yes, but passive PoE is almost universally at 24v, and | per the Ethernet spec (as quoted above) an Ethernet PHY | should tolerate 24v fine. This is important as transients | from nearby lightning or occasionally even coupling to | power cables can produce this kind of voltage. Ethernet | connectors are magnetically coupled for protection from | these transients. | | The problem with PPoE in these cases is, I think, not the | voltage so much as the current. The continuous 24v supply | may overheat the magnetic coupling transformer and cause | it to fail. Some Ethernet interfaces, usually on telecom | equipment and quality switches, have over current | protection to prevent this. Unfortunately consumer | devices usually don't. | | It's important to understand this because 802.3af etc. | _does_ provide power without being asked - as a rest for | a characteristic resistance on the receiver. Otherwise it | wouldn 't know if a PoE-capable device was connected. Up | to 20v can be applied during this process but it is time | limited. In general, 802.3 PoE supplies must monitor the | current usage of the powered device and cut off power if | it is too high or even too low for more than a short | period of time. This is in part to prevent this | overheating problem on devices that might, for some | coincidental reason, fall into the appropriate resistance | range to activate PoE. | | In other words, 24v or even hundreds of volts for a few | seconds is perfectly safe. 24v for minutes is likely to | cause damage to devices without better protection than | the spec requires. Old Ethernet equipment used to make | the non-isolated components relatively easy to replace so | that repairs after a problem like this were easier but | now the isolation is a tiny surface mount part and | replacing it will require tools and skill. | wslh wrote: | A few days ago I found "Charging My MacBook Air M1 with a | Standard Mobile Phone USB Charger" [1]. PoE it is in similar | ranges. | | [1] https://news.ycombinator.com/item?id=36893299 | mmastrac wrote: | I use PoE extractors to power a few different devices in my | house, including RPis and some non-PoE switches. It's | ridiculously easy to use them, but you generally need to know the | voltage you want ahead of time. | EvanAnderson wrote: | PoE splitters with USB outputs are really handy since | "everything" plugs-in to USB now. | poolopolopolo wrote: | Holy moly, didnt know these things existed :O and fairly cheap | as well, always though PoE a bit of useless since most devices | dont support it and it was (is?) quite dangerous. | mmastrac wrote: | If you have modern PoE dispensing (?) equipment it's pretty | safe as the devices all auto-negotiate. | erwincoumans wrote: | We powered the Mac Mini M1 using 12V DC, bypassing the built-in | AC power adapter, and used it for some quadruped robot | experiments. Some details on the connector are here: | https://www.ifixit.com/Answers/View/574827/What+PSU+connecto... | (that article mentions Mac Mini 2018 but the connector/pinout | still works fine for Mac Mini M1) | [deleted] | metadat wrote: | > Thanks to the power efficiency of Apple Silicon, the M1 Mac | mini was the perfect hardware to test out PoE, as on idle, the | device only consumes 6W. When some load is applied to the | internals, that power draw can go up to 40W. After some thorough | research, we found out that the maximum throughput of Power over | Ethernet was 15.4W and that too over varying voltages, which are | details that Ivan had left out when showing off his findings on | Twitter. | | The last sentence has enough typos that I'm not able to follow | what they're trying to say. What happens when the machine | requires more than 15.4W? If the thing isn't actually usable or | stable in real-world scenarios, this becomes a lot less exciting. | | It'd also be more interesting if the full components list of what | was added to the inside of the machine to make this possible was | shared. | | Edit: Thanks to @ravetcofx for revealing how more power can be | delivered over PoE https://news.ycombinator.com/item?id=36962808 | lights0123 wrote: | The article simply assumes that the creator only supports the | original POE when they say "POE". There's a good chance they | used a PoE+ or PoE++ adapter that supports more wattage. | tredre3 wrote: | There are more details in the twitter thread, including a table | of PoE standards: | | https://twitter.com/Merocle/status/1686093369322176512 | | > What happens when the machine requires more than 15.4W? | | The voltage will sag and the machine will likely crash! | ravetcofx wrote: | " the M1 Mac mini was the perfect hardware to test out PoE, as on | idle, the device only consumes 6W. When some load is applied to | the internals, that power draw can go up to 40W. After some | thorough research, we found out that the maximum throughput of | Power over Ethernet was 15.4W " | | They'll have to bump it up to 802.3bt (Poe ++) which can support | 60W. | | Cool Project though, I've been wanting to mod my Mac Mini m1 to | run off USB-C PD which should be possible with modification | because it uses the same PD IC as the Macbooks (CD3217) which | could mean I could get it to eventually run off of a battery pack | rfgmendoza wrote: | i would actually like being able to power my mac mini with just | a usb-c dock like a macbook | dheera wrote: | I'm very skeptical of PoE now after 3 PoE adapters killed 3 | Raspberry Pis I have. | | I wouldn't want to risk something more expensive to that shit. | | At this point I'd rather just have straight up 19V + and - | cables bundled together with the Ethernet with some heatshrink | around the whole thing to make it look like 1 cable. | CameronNemo wrote: | You sure you want to blame poe as a whole instead of the RPI | hat? | haswell wrote: | PoE is used extensively in network deployments involving | rather expensive hardware. | | I understand the instinct to avoid it at this point, but I'm | curious what happened in your case because I've never | experienced issues. | | I did work somewhere where someone fried equipment by | incorrectly terminating a batch of Ethernet cables thereby | sending voltage to the wrong place. | bitbckt wrote: | Minor correction: 802.3bt added 51W (Type 3) or 71W (Type 4). | 60W isn't a standard power level. Some switches support up to | 95W per port with PoH. | OJFord wrote: | Surely they're all ' _up to_ '? It's not 'you must sink this | much current or else not compliant'? | | It seems like a weird thing for TFA to say anyway - my PoE[+] | switch was the cheapest 8 port I could get a few years ago on | Amazon, and does 30W per port. I don't really understand how | you could look into it at all, be willing to attempt the | hack, but not use a switch (or injector or whatever) that's | capable of powering it under load. | bitbckt wrote: | Hah, yes they are all 'up to' on the device side. A switch | port or injector is not compliant with a particular | standard if it does not provide for the type-specific load, | however. | r00fus wrote: | What's the goal of having a MacMini running off an external | battery? I mean, it seems less cost effective than just getting | a MB Air and not using the screen... | tyingq wrote: | That it happens to be 12 volts DC has some value versus | whatever power loss an inverter has for use in a vehicle. | Though I'm with you on the relative ease of starting with a | laptop instead. | lapetitejort wrote: | The goal of most of these projects are usually to demonstrate | that they're possible. Actual use cases are left as an | exercise for the reader. | Dalewyn wrote: | The scientists were too busy asking if they could, because | it's not their job to ask if they should. | simlevesque wrote: | > it seems less cost effective than just getting a MB Air and | not using the screen... | | how ? why would paying for a screen and not use it be cheaper | ? | arcticbull wrote: | Economy of scale, mostly. | SmellTheGlove wrote: | No idea, but if they got it running on USB PD, battery pack | aside, it would make it a one cable connection to a monitor | that has PD support. Multiple cords don't actually bother me | but it sounds kinda neat. | | Anyhow I guess the goal is "because you can" | dylan604 wrote: | This would be fun for when LEOs come in to take your | computer, they can easily keep it powered so all of the | decrypted keys stay in memory. Killing power means going back | to an encrypted state. In high profile cases for desktops, | there's techniques for splicing the power cable to switch to | a battery pack. This would make it much easier for the | unskilled LEO to take your shit. Cause we all know you're the | one their after. Sleep tight! ;-) | bravetraveler wrote: | Avoiding the inevitable spicy pillow seems like a good reason | | An external/easily replaceable battery would be excellent | come time to deal with cell age | bravetraveler wrote: | Does this read like an attack against Apple laptops | specifically, or something? Already -2 five minutes after | posting it. | | Leaving as-is for feedback. I don't get the controversy. I | could've been a jerk and said just buy a UPS - this is an | established concept. | | Edit: thank you kind souls for restoring the imbalance - | carry on :D | poolopolopolo wrote: | cheaper and bigger batteries? always replaceable in the | future? And tbh laptop batteries are not meant to be used | 24/7, personally would avoid it. | OJFord wrote: | I could see it making sense in a 'van life' context to use a | smaller local battery rather than plug everything in to your | main leisure battery. Use the latter to charge Makita packs | say and then run most other stuff off those (there's a decent | amount of open 3D printable adapters for them, as well as | third-party/AliExpress stuff). ___________________________________________________________________ (page generated 2023-08-01 23:00 UTC)