All About Cats, And What Ethernet Classifications Mean Beyond ‘Bigger Number Better’

November 7, 2023 by Maya Posch 48 Comments

Although it probably feels like forever to many of us since Category 5 Ethernet cabling became prevalent, now that 2.5 and even 5 Gbit Ethernet has trickled into the mainstream, a pertinent question that many probably end up asking, is when you should replace Cat-5e wiring with Cat-6, or even Cat-7. Since most of us are likely to use copper network wiring for the foreseeable future in our domiciles and offices, it is a good question that deserves a good answer. Although swapping a Cat-5e patch cable with a Cat-7 one between a network port and computer is easy enough, replacing all the network cable already pulled through the conduits of a ‘future-proofed’ home is not.

The good news is probably that Category 8 Class II (Cat-8.2) is all you need to run your 40 Gbit Ethernet network with standard twisted pair wiring. The bad news is that you’re limited to runs of only thirty meters before signal degradation begins to kick in. If you take things down a notch to Cat-6A or Cat-7 (ISO/IEC 11801 Class E_A and F, respectively), you can do 100 meter runs at 10 Gbit/s just like 100 meters runs at 1 Gbit/s were possible with Cat-5e before. Yet what differentiates these categories exactly?

Continue reading “All About Cats, And What Ethernet Classifications Mean Beyond ‘Bigger Number Better’” →

Adding Power Over Ethernet Support To A Mac Mini

August 14, 2023 by Maya Posch 8 Comments

Wiring up a Mac Mini's new PoE module. (Credit: Ivan Kuleshov) — Wiring up a Mac Mini’s new PoE module. (Credit: Ivan Kuleshov)

Despite all the fancy features on modern Apple Mac systems like USB-C and Thunderbolt, they have one glaring omission: the absolute lack of any form of Power-over-Ethernet (PoE). This is an issue that [Ivan Kuleshov] sought to rectify with some delicate board-level surgery. Since the original Ethernet jack on the lucky vic^Wrecipient M1 Mac Mini does not have integrated magnetics (magjack), tapping into the appropriate lines would have been rather awkward, with questionable results on the side of the PCB traces that would suddenly be used for PoE purposes they were never designed for.

Rather than choosing this level of experimentation, [Ivan] decided to patch in the Silvertel AG5412 PoE module with plentiful patch wires. This involved removing the Ethernet jack and bypassing the PCB and the magnetics module completely for the new PoE functionality, instead using the magnetics pilfered from a magjack and routing from there back to the mainboard as well as to the PoE module’s inputs. Continue reading “Adding Power Over Ethernet Support To A Mac Mini” →

If Not Ethernet…

June 17, 2023 by Al Williams 64 Comments

It is hard to imagine today, but there was a time when there were several competing network technologies. There was Ethernet, of course. But you could also find token ring, DEC Net, EcoNet, and ARCNet. If you’ve never dug into ARCNet, [Retrobytes] has a comprehensive history you can watch that will explain it all.

Like token ring, ARCNet used a token-passing scheme to allow each station on the network to take turns sending data. Unlike token ring and Ethernet, the hardware setup was much less expensive. Along the way, you get a brief history of the Intel 8008 CPU, which, arguably, started the personal computer revolution.

Like most networking products of the day, ARCNet was proprietary. However, by the late 1980s, open standards were the rage, and Ethernet took advantage. Up until Ethernet was able to ride on twisted pairs, however, it was more expensive and less flexible than ARCNet.

The standard used RG-62/U coax and either passive or active hubs in a star configuration. The coax could be up to 2,000 feet away, so very large networks were feasible. It was also possible to share the coax with analog videoconferencing.

Looking back, ARCNet had a lot to recommend it, but we know that Ethernet would win the day. But [Retrobytes] explains what happened and why.

If you missed “old-style Ethernet,” we can show you how it worked. Or, check out EcoNet, which was popular in British schools.

It’s Ethernet, From An SPI Interface

December 19, 2022 by Jenny List 37 Comments

Over the years as microcontrollers have become fast enough to do the heavy lifting, we have become used to 10 megabit Ethernet being bit-banged from interfaces it was never meant to emerge from. We think however that we’ve never seen one driven from an SPI interface, so this one from [Ivan] may be a first. With a cleverly designed transceiver using logic chips, it even offers a chance to understand something about the timing of an Ethernet interface, too.

The differential logic signals derived from a simple Ethernet transceiver can be read by an SPI bus, but for the lack of a clock line. The challenge was then to construct a circuit the would construct the required clock pulses from the state changes on the data line. This would become a monostable with XOR gate, and a shift register to handle the clock during the preamble phase.

The resulting circuitry fits neatly on a shield for the ST Nucleo 64 board, where while it might not be the obvious choice for an Ethernet shield it certainly does the job.

If unexpected Ethernet is your thing, how about the i2s peripheral on an ESP8266?

Power Over Ethernet, Explained

December 8, 2022 by Jenny List 42 Comments

Most readers will be familiar with Ethernet networks in some form, in particular the Cat5 cables which may snake around the back of our benches. In a similar vein, we’ll have used power over Ethernet, or PoE, to power devices such as webcams. Buy a PoE router or switch, plug in a cable, and away you go! But what lies behind PoE, and how does it work? [Alan] has written a comprehensive guide, based on experience working with the technology.

What we get first is a run-down of the various topographies involved. Then [Alan] dives into the way a PoE port polls for a PoE device to be connected, identifies it, and ramps up the voltage. Explaining the various different circuits is particularly valuable. The final part of the show deals with the design of a PoE module, with a small switching power supply to give the required 48 volts.

All in all, this should be required reading for anyone who works with Ethernet, because it’s one of those things too often presented as something of a black box. If you’re thirsty for more, it’s a subject Hackaday have touched on too in the past.

Magnetic jack version of the bit-bang ethernet peripheral for Raspberry Pi Pico

Bit-Banging Bidirectional Ethernet On A Pi Pico

December 3, 2022 by Dave Walker 38 Comments

These days, even really cheap microcontroller boards have options that will give you Ethernet or WiFi access. But what if you have a Raspberry Pi Pico board and you really want to MacGyver yourself a network connection? You could do worse than check out this project by [holysnippet] that gives you a bit-banged bidirectional Ethernet port using only scrap passive components and software.

This project is similar to one we shared back in August by [kingyo], but differs in that what [holysnippet] has achieved is a fully-functional (albeit only around 7 Mbps) Ethernet port, rather than a simple UDP transmit device. The Ethernet connection itself is handled by the lwip stack. Connection to the RJ45 socket can be made from any of the Pi Pico pins, provided TX_NEG is followed directly by TX_POS, but the really hacky part is in the hardware.

schematic of Pi Pico bit-banged ethernet peripheral — Schematic showing the empirically-determined passive component values required.

Rather than developing hardware that would protect the Pico, this design admits that it “shamefully relies on the Pico’s input protection devices” to limit the Ethernet voltages to 3.3 V.

You’ll need an isolation transformer from some old Ethernet-enabled gear (either standalone or as part of a magnetic jack), but then it’s only resistors and capacitors from there. There are warnings not to connect this to PoE networks for obvious reasons, and the component layout needs to keep in mind the ~20 MHz frequencies involved, but to get this working at all feels like quite a feat.

Normally, there’d be no reason to go to these lengths, but it’s always educational to see if it can be done and, with the current component shortages, this is another trick to keep up your sleeve for emergencies!

Putting ports where they shouldn’t belong is not a new idea, of course. Back in the day we even shared an inadvisable ATTINY implementation of bit-banged Ethernet with no protection at all.

Thanks to [biemster] for the tip-off

Ethersweep: An Easy-To-Deploy Ethernet Connected Stepper Controller

September 7, 2022 by Dave Rowntree 35 Comments

[Neumi] over on Hackaday.IO wanted a simple-to-use way to drive stepper motors, which could be quickly deployed in a wide variety of applications yet to be determined. The solution is named Ethersweep, and is a small PCB stack that sits on the rear of the common NEMA17-format stepper motor. The only physical connectivity, beside the motor, are ethernet and a power supply via the user friendly XT30 connector. The system can be closed loop, with both an end-stop input as well as an on-board AMS AS5600 magnetic rotary encoder (which senses the rotating magnetic field on the rear side of the motor assembly – clever!) giving the necessary feedback. Leveraging the Trinamic TMC2208 stepper motor driver gives Ethersweep silky smooth and quiet motor control, which could be very important for some applications. A rear-facing OLED display shows some useful debug information as well as the all important IP address that was assigned to the unit.

Control is performed with the ubiquitous ATMega328 microcontroller, with the Arduino software stack deployed, making uploading firmware a breeze. To that end, a USB port is also provided, hooked up to the uC with the cheap CP2102 USB bridge chip as per most Arduino-like designs. The thing that makes this build a little unusual is the ethernet port. The hardware side of things is taken care of with the Wiznet W5500 ethernet chip, which implements the MAC and PHY in a single device, needing only a few passives and a magjack to operate. The chip also handles the whole TCP/IP stack internally, so only needs an external SPI interface to talk to the host device.