Show HN: We Made The World's Smallest and Cheapest Network Switch

I think you should submit your project page [1] as another show HN, I found it to be interesting

Some thoughts:

- Agreed with not using I2C, I2C has been identified as a root cause in several cubesat mission failures: https://pure.tudelft.nl/ws/portalfiles/portal/10531886/art_3... and https://webapps.unsworks.library.unsw.edu.au/fapi/datastream... (yes clock stretching is evil). I2C should be banned for multi board communication

- Classic CAN have very small 8 byte MTU with frame preemption, which is actually useful for its intended purpose of time critical automotive data transfer. If that 4 byte brake packet is blocked by a 1500 byte packet then your car will crash and explode. But the tradeoff is that this makes it very slow for bulk data transfer

"making this product sector a tiny bit better" is exactly what MUREX is all about :). It's something we honestly believe in and will continue working on as long as we're around. Believe it or not, the Ethernet Switch was the least problematic piece of hardware in our tech stack! If you want to take a look, we have our other boards in the docs as well. Your rocket is so f*ing cool as well! I definitely want to do something similar in college.

Congratulations MUREX Robotics team, great job!

There are products at different price points on the market, for example this 55x55mm switch from my company Brainboxes[1] is sub $50. We choose that size so that we could also produce a gigabit option with the exact same footprint. We opted for microMatch[2] style connectors as you can get board to board as well as board to cable options.

Your co-leads decision to buy-in is quite common, as you can reduce time to market and also not have to manage the component lifecycle if you go with an off the shelf option.

[1] https://www.brainboxes.com/product/pure-embedded/pe-505

[2] https://www.te.com/en/products/brands/micro-match.html?tab=p...

Worth noting though that the switch you linked claims to be a gigabit switch while the switch from murex is 100Mbpbs.

Not sure if that justified the price difference

This isn't a desktop Ethernet switch. Lots of robotic parts like industrial cameras and fancy laser sensors use Ethernet for interfacing instead of USB or RS232C. Doing so solves cable length limitations and connection stability issues of those peripheral buses. There would be penalties and overheads of (mis?)using inter-node communication protocols like Ethernet (and TCP/IP), but those tradeoffs are completely acceptable.

What is not acceptable is full sized switches inside of a robot: they're way too bulky. You may be looking into installing a switch inside a humanoid upper arm or inside pelvis. Regular switches and hubs don't fit there.

This product solves that specific robotics packaging problem. Electrically it's a switch/hub, physically it's much smaller than that, that's the point.

I suspect the combination of being able to dissipate 3.4kW of power, and the requested size and noise constraints may put this combination of features firmly beyond reasonable, even before considering cost.

But there is always room to hope. :)

For example, a TrendNet 10/100 compact switch (not a hub) goes for $7.31 including shipping on eBay and it comes with a case and a power supply

A 1G switch from Ali with a case, power supply, and the RJ45 connectors is also under $10.

Hello, yes. Unfortunately it is hot to the touch. The board doesn’t draw 800mA, but it does get to like 60C. Max, the main designer for V2, said a heatsink is recommended. Our thermal via solution keeps it within somewhat safe temps. We wanted to keep the cost low, so we opted for the LDO. In our robot we do direct 3.3V with a buck that does 3.3 for our entire system. That’s Max’s power board.

If you're doing tethered ROV stuff, the weight of the teather is a big big deal, so adding 4 additional wires is a non starter. For the stuff that goes extremely deep, they use fiber because it's much lighter. It presents significant cost increases of course, which, you'd want to avoid if you can.

I’m not sure what your background is, but 100Mb Ethernet is still rather common in embedded devices and applications where the network protocol is primarily intended to facilitate UART serial communication. Just as a general note for context, I will defer to their more specific answer for this particular application.

Neat project!

GigE needs twice the pin count. IMHO, there's not much room on the board for any more i/o. Certainly gigabit is nice, but there's plenty of applications where 100M is more than plenty.

As much as modern Ethernet standards are much nicer (my house is wired for and running 10Gb everywhere, with 40Gb Infiniband to a couple locations too), 100Mbps still has its place. Specifically, anything embedded, slow, and/or cheap. No reason to spend the extra money on 4 more wires and pins and trace routing if your microcontroller only sends a few packets/second.

Hi! I'm Altan, another member of Murex. Many of the design decisions behind the switch were driven by the requirements of our underwater robot. In our case, the communication speed was capped by the transfer speed achieved over our tether (we use galvanically isolated OFDM to inject data over our powerlines). Since size and cost were our primary goals, 100mbit was more suitable than gigabit ethernet. While it would have been cooler to have a gigabit switch, it would also increase the size and cost.

Hello! I just want to clarify some of these points. Saying it is the world's smallest switch is a bold claim, and there are definitely alternative options around. However, our board scales really well. The main reason we say it's the cheapest is because the real BOM is only around 4-5 dollars. Our small run of ~25 boards came out to ~$7 each. If you agree with my interpretation, perhaps the words "smallest and cheapest" can be together?

Magnetics: We have built-in "external" magnetics, so the physical ports don't have the magnetic inductors required in the Ethernet standard. This makes the ports super small, allowing us to use 1.25mm pitch Molex Picoblade connectors. Again, thanks for the suggestions. We're still learning and the team is taking all the comments very seriously.

Given this was made by a high school robotics team and it accepts up to 12V, it's likely that the intended use case is on a robot that already has a 12V battery

Fast Ethernet +/- pins go through a special 1-turn transformer for electrical isolation installed between the PHY and RJ45 connectors, commonly referred to as "the magnetics" in Ethernet world. It's physical ferrite and copper object molded like a chip, therefore it can't be trivially integrated into a silicon or in MCM. Hence most Ethernet chip require one external to the chip, and in this case it is indeed external to the chip, and integrated into the board at the same time.

(yes a cap in-line works too if you know what you're doing)

You can get 40+ Gb/s over USB-C or connections like DisplayPort and HDMI by using thick expensive cables that top out around 10ft of length. Beyond that, price starts shooting up as you get either optical transceivers or active retimers/redrivers built into the cable assembly.

Ethernet over copper is designed for cable runs of over 300ft and has to be much more forgiving of poor quality cables and connectors. That means for the same level of complexity and power consumption in the transceivers, you're just not going to be able to get as much bandwidth.

Ethernet equipment suitable for 2.5Gb/s and 5Gb/s in consumer equipment (cheap, low power) is now readily available, but there's not enough demand to drive pricing down to parity with 1GbE and completely supplant it. 1GbE is good enough for most consumer use cases, especially given the dearth of multi-Gig WAN connections in the consumer market, the lack of popular use cases that would benefit from slightly faster LAN connections, and the continuing improvements to WiFi.

Combination of power and distance.

Copper Ethernet standards tend to be specified for over 30 metres, and go (preferably) up to 100m. That’s pretty tricky to do, you need quite thick cable with individually foil shielded pairs to achieve those kind of long distances at 10Gbps. 40 Gbps USB-C on the other hand is recommended to travel over a maximum of a metre or so of cable, with the recommended being 0.8m (2.6ft) of cable or less! Thunderbolt cables that go longer need active driver chips inside the cable in each connector to make the whole thing work.

Then there is the power issue, 10Gbps Ethernet uses significantly more than 1Gbps, so a 40GBase-T switch would be even more power hungry.

The combination of these has meant that basically most people just use fibre if they need more bandwidth.

The intended use-case for this board is some robotics applications. I don't think parts of robots need to communicate via gigabit. 10/100 Base-T is presumably easier to implement and thus cheaper and smaller (which is the point of this project)

2.5gbit is quite common and cheap.

How about the Mikrotik CRS510-8XS-2XQ-IN? 2x 100G uplink, 8x25G/10G/1G downlink, DC power input, and only 320mm (12.5in) wide.

We only found ~gigabit and ~fast ethernet chipsets that are easily accessible. However, it's definitely something we will think about in the future! Thanks for the suggestion!

Hi, I'm Max, the lead designer of this V2 revision. You're absolutely correct! My team and I were not aware of BotBlox's 3-port switch, so a more specific description would be the world's smallest 5-port unmanaged switch. The smallest commercial alternative we found was also BotBlox's 5-port unmanaged switch [1], which we beat in both size and cost.

Once again, our mission is to create open-source, cost-effective, and accessible electronics for as many people as possible -- I think our board is much more attractive in that respect and a win in my book :)

[1] https://botblox.io/products/small-ethernet-switch

Low volume hardware pricing always look infuriatingly high, but they also start looking hopelessly low once you've dipped toes into it and tried multiplying your spent development man-hours with McDonalds wages or tolerable unit price by expected sales volume.

I've never heard of Blue Robotics, but I doubt that $175 product ships 1k units/year, and even if they did, that's $170k revenue, or 2x entry level engineers salary worth of raw recovered cash before factoring in any expenditure whatsoever, let alone taxes and HR. It probably hardly feeds one, and that's based on an optimistic hypotheticals that they ship a thousand of that product every year.

Large scale multinational corporations ship in orders of million units. That makes it way easier to amortize non-recurring engineering and ship small products virtually at cost.

Absolutely not!! This is what MUREX is all about. We are on a mission to show anybody can do this. Change the world one small bit at a time. This was all self learned from the internet, trial and error, lots of passion, and this community. Our mentor doesn’t have a background in engineering so he just gives us lots of emotional support and some physics help. Love you guys!! This is amazing.

Most major chipsets have their design specs in PDF format online with all the info there for interfacing on a hardware level. Many drivers these days are open source. Kicad is free to use for designing PCBs.

And finally https://www.youtube.com/@PhilsLab has some good tutorials.

Finally, goo into things with an attention to detail to polish a board. A hobby board takes far less time than a product board, but all it is is time and thinking about each attribute more. You don't need third level education to have that work ethic.

Best of luck!

Given the caseless PCB and non-RJ45 connectors, it looks like it's designed to be used on robots, and I can certainly see it being used that way in my robotics team

Hello, I'm Crane and I'm also on the MUREX Robotics team. The price point we are aiming towards is $7-$10. Our network switch is currently used for personal purposes, in our underwater robot, and we look forward to expanding it for industrial purposes.

Seriously, my high school was mostly boring and pointless. I’m in awe of the opportunities some kids are able to find/create today.

Thank you! Attempt the impossible :)

Thanks for asking! That is a very good question. However, we use bog-standard Ethernet connections, so using Fast Ethernet is super straight forward. Just splice the cable and we're all good.

Hi, I'm Crane and I am also part of MUREX robotics and this is very inspiring to me as an electrical engineer who is starting out.

Thank you! It means a lot to our team!!

Unfortunately, it's not really useful for our use-case. Our robot only uses ~kB amount bandwidth.

unleashing innovation :o

You can buy them right of Digikey by searching "4 position Molex Picoblade cable assemblies" or similar!

Our mission is to create open source electronics that democratize technology for as much people as possible! This is a full list of stuff we've done this year: https://www.murexrobotics.com/mrxEE. It isn't a requirement for the MATE ROV competition (I wish it was though; it would be super cool!).

That would be super cool! I'm not sure how it'd work together. I would think we need a higher speed fabric-type connection.

Thank you! Noted.

Hello! I'm Osbert, another elec member on MUREX. For sure, we use 115k2 UART on our "custom" ESC serial communication protocol, MASCP (murex async serial communication protocol). We stream 2 IP cameras, our CM4 board (open source as well!), and our mrxPLC (DC powerline data injection technology). Thanks for the encouragement. It means a lot to our team!

Thank you so much! This energy has waked us all up!! We’re all living together right now preparing for the world championships next week in TN! This is soooo exciting.

Hello! It supports 100Mb throughput, nothing more, nothing less. It's been tested with iperf. I believe it switches at line rate, but don't quote me on that haha. The chip's extra features can be enabled with an EEPROM, which we removed to cut costs and size further. It's on V1 though.

Thanks! Do it right, do it MUREX!

Yes! It is here: https://github.com/murexrobotics/electrical-2024 under networking/switch Edit: We use KiCAD Nightly 8.99 for the new features. You can view our boards easiest with kicanvas.org and just pasting in the https://github.com/murexrobotics/electrical-2024/tree/main/n...

Thank you it truly means a lot to the team!!

I actually met with the Sergiy as well a few months back! Super cool guy. I also highly recommend quilter - thought it was super cool (not paid haha).

Quilter doesn't have the best support for impedance matched traces. We do 90Ω on a 4 layer board and Bob Smith termination which has some pretty goofy design requirements.

Maybe! If you’d like one, please email me at byran@mrx.ee!

Thank you! This goes in our underwater robot, and it has all the features that let the system work without anything else. However, we will definitely keep your suggestions in mind for our future revisions. We're seeing how to make this board even smaller, while keeping the cost down. 7 dollars (technically 6.9) is the mark to beat.

Ah you're right –– the team and I were not aware of BotBlox's 3-port switch! I guess a more specific description would be the world's smallest 5-port unmanaged switch. We do however beat BotBlox's similar 5-port unmanaged switch [1] slightly in size and miles in cost. I'm Max by the way, the lead designer of this revision.

[1] https://botblox.io/products/small-ethernet-switch

Thank you so much! We're so happy you like it. It means a lot to us. We will be adding more pictures right now!

We're exposing 1.25mm pitch Molex Picoblade connectors to make the board as small as possible. The built-in magnetics allow it to be connected to any Ethernet device just from spicing into an RJ45 connector.

Thank you!

Thank you! We also have those switches. They are fantastic cheap tech as well.

Please email us at byran@mrx.ee for now!

Please send us an email! We will try our best to get you geared up. byran@mrx.ee

That’s one area we are exploring!

Thank you so much! Super excited for college. I think it should fit right into an UAV. I see a lot of use from Ardupilot forums (which we use). It’s the reason we have the LDO as well. We wanted to keep the application possibility open.