MoCA Networking Is A Niche Solution For Coax Lovers

November 3, 2022 by Lewin Day 63 Comments

When it comes to networking these days, the vast majority of our devices are connected wirelessly. Beyond that, we’re all familiar with the Cat 5 and Cat 6 cables that form the high-capacity Ethernet networks in our homes, schools, and offices.

It’s only if you go back to the very dawn of Ethernet that coaxial cables are relevant… right? Wrong! MoCA networking is all about coaxial cables, designed to hook up devices over cable TV infrastructure!

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Building A Local Network With LoRaWAN

October 22, 2022 by Bryan Cockfield 40 Comments

At its core, the Internet is really just a bunch of computers networked together. There’s no reason that there can’t be other separate networks of computers, or that we all have to tie every computer we have to The One Internet To Rule Them All. In fact, for a lot of embedded systems, it doesn’t make much sense to give them a full network stack and Cat6e Ethernet just to report a few details about themselves. Enter LoRaWAN, a wireless LAN that uses extremely low power for Internet-of-Things devices, and an implementation of one of these networks in an urban environment.

The core of the build is the LoRaWAN gateway which sits at the top of a tall building to maximize the wireless range of all of the other devices. It’s running ChirpStack on the software side and uses a Kerlink Wigrid station to broadcast. The reported range is a little over 9 km with this setup. Other gateways can also be added, and the individual LoRa modules can report to any available gateway. From there, the gateways all communicate back to the central server and the information can be sent out to the wider network, Internet or otherwise.

The project’s creator [mihai.cuciuc] notes that this sort of solution might not be best for everyone. There are other wide area networks available, but using LoRaWAN like this would be likely to scale better as more and more devices are added to the network. For some other ways that LoRa can be used to great effect, take a look at this project which builds an off-grid communications network with it.

Tiny Thin Client Is Small But Compatible

October 13, 2022 by Al Williams 10 Comments

We were impressed with [moononournation’s] tiny thin client project. It claims to use an Arduino, but as you might guess it is using the Arduino software along with a network-enabled microcontroller like an ESP32. The impressive part is that it is standards-compliant and implements VNC’s RFB protocol.

The original coding for RFB on Arduino is from [Links2004] and armed with that, the thin client is probably easier to create than you would guess. However, this project wanted to use a larger screen and found that it led to certain problems. In particular, the original code had a 320×240 display. This project was to use an 800×480 display, but with the limits on the ESP32, the frame rate possible would be under 7 frames per second. The answer was to combine a 16-bit parallel interface with better compression back to the VNC server.

The little keyboard is probably not very practical, but it is compact. That would be another easy thing to modify. Currently, the keyboard uses I2C, but it would be straightforward to change things up. This would be a worthy base to build a bigger project on top. A 3D printed enclosure would be nice, too.

We’ve seen a number of projects built around commercial thin clients. Some from defunct businesses are good sources for obscure parts, too.

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“The Era Of Distributed, Independent Email Servers Is Over”

September 7, 2022 by Jenny List 138 Comments

Imagine the Internet had begun its life as a proprietary network from a major software vendor rather than evolved as a distributed network shared by researchers. It’s a future that almost came to pass for consumers in the 1990s when walled gardens such as AOL or the original incarnation of MSN were all the rage, but thankfully the world took the Internet course.

Though there are many continuing threats to Internet freedom we can still mostly use the network our way, but with sadness we note that one piece of Internet freedom may have drawn to a close. [Carlos Fenollosa] has written a lament about how the outlook for anyone running their own mail server now looks bleak.

At its heart is spam, or indeed the heavy-handed measures taken by large email providers to combat it. Spotting and canning spam is computationally expensive, so the easiest way to stop a spammer is to recognize their activity and block it at the network level. Thus a large email provider will instantly block large IP ranges when it detects they hold a spammer, with the collateral damage of also blocking any legitimate email servers in the same range such that their mail just doesn’t get through. Since spam is such a widespread problem, as [Carlos] points out it’s less of a case of if your server has this problem, but when. This functions essentially as something of a racket, in which large email providers have the power to ensure that any email not generated from amongst themselves is unlikely to reach any of the millions of addresses under their care, and the only recourse an operator of a small email domain has is to use the services of one of them.

He has something of a manifesto as to how this problem can be addressed, and we think that it’s important enough that you should take a look. Maintaining email as something beyond the control of large providers is too important not to.

Thanks [Thomas Steen Rasmussen] for the tip.

Header image: RRZE, CC BY-SA 3.0.

The Pi Pico board on top of a white box with an Ethernet jack, with a sensor module plugged onto the Pico's pin headers. A black MicroUSB and a green Ethernet cable are connected to this device.

An Elegant Ethernet Library For Your Next RP2040 Project

August 27, 2022 by Arya Voronova 17 Comments

A few days ago we covered a project that brought Ethernet connectivity to the Raspberry Pi Pico using little more than some twisted pair and a RJ-45 connector. It was a neat trick, but not exactly ready for widespread adoption. Looking to improve on things a bit, [tvlad1234] has taken that project’s code and rewritten it into a friendly library you can use with any RP2040 board.

In case you missed it, the initial demo did 10BASE-T transmission by bit-banging with the PIO, and was able to send UDP messages to devices on the wired LAN. It was an impressive accomplishment, but its code didn’t make it easy to build your project around it. This new library makes UDP messaging as easy as a printf, offloading all non-PIO-managed Ethernet signal work onto the RP2040’s second CPU core. The library even generates a random MAC address out of your flash chip’s serial number!

As a demonstration of the new library, [tvlad1234] has put together a simple Ethernet-connected temperature monitor using the BMP085 or BMP180 sensor connect over I2C. If you feel like you could use an Ethernet transmit-only sensor in your life, browsing the source code would be a great start.

Bit-Banged Ethernet On The Raspberry Pi Pico

August 26, 2022 by Dave Rowntree 29 Comments

Whilst the Raspberry Pi RP2040 is quite a capable little chip, on the whole it’s nothing really special compared to the big brand offerings. But, the PIO peripheral is a bit special, and its inclusion was clearly a masterstroke of foresight, because it has bestowed the platform all kinds of capabilities that would be really hard to do any other way, especially for the price.

Our focus this time is on Ethernet, utilizing the PIO as a simple serialiser to push out a pre-formatted bitstream. [kingyo] so far has managed to implement the Pico-10BASE-T providing the bare minimum of UDP transmission (GitHub project) using only a handful of resistors as a proof of concept. For a safer implementation it is more usual to couple such a thing magnetically, and [kingyo] does show construction of a rudimentary pulse transformer, although off the shelf parts are obviously available for this. For the sake of completeness, it is also possible to capacitively couple Ethernet hardware (checkout this Micrel app note for starters) but it isn’t done all that much in practice.

UDP is a simple Ethernet protocol for transferring application data. Being connection-less, payload data are simply formatted into a packet buffer up front. This is all fine, until you realize that the packets are pretty long and the bitrate can be quite high for a low-cost uC, which is why devices with dedicated Ethernet MAC functionality have a specific hardware serialiser-deserialiser (SERDES) block just for this function.

Like many small uC devices, the RP2040 does not have a MAC function built in, but it does have the PIO, and that can easily be programmed to perform the SERDES function in only a handful of lines of code, albeit only currently operating at 10 MBit/sec. This will cause some connectivity problems for modern switch hardware, as they will likely no longer support this low speed, but that’s easily solved by snagging some older switch hardware off eBay.

As for the UDP receive, that is promised for the future, but for getting data out of a remote device over a wired network, Pico-10BASE-T is a pretty good starting point. We’ve seen a few projects before that utilize the PIO to generate high speed signals, such as DVI, albeit with a heavy dose of overclocking needed. If you want a bit more of an intro to all things Pico, you could do worse than check out this video series we highlighted a while back.

Bufferbloat, The Internet, And How To Fix It

August 18, 2022 by Jonathan Bennett 48 Comments

There’s a dreaded disease that’s plagued Internet Service Providers for years. OK, there’s probably several diseases, but today we’re talking about bufferbloat. What it is, how to test for it, and finally what you can do about it. Oh, and a huge shout-out to all the folks working on this problem. Many programmers and engineers, like Vint Cerf, Dave Taht, Jim Gettys, and many more have cracked this nut for our collective benefit.

When your computer sends a TCP/IP packet to another host on the Internet, that packet routes through your computer, through the network card, through a switch, through your router, through an ISP modem, through a couple ISP routers, and then finally through some very large routers on its way to the datacenter. Or maybe through that convoluted chain of devices in reverse, to arrive at another desktop. It’s amazing that the whole thing works at all, really. Each of those hops represents another place for things to go wrong. And if something really goes wrong, you know it right away. Pages suddenly won’t load. Your VoIP calls get cut off, or have drop-outs. It’s pretty easy to spot a broken connection, even if finding and fixing it isn’t so trivial.

That’s an obvious problem. What if you have a non-obvious problem? Sites load, but just a little slower than it seems like they used to. You know how to use a command line, so you try a ping test. Huh, 15.0 ms off to Google.com. Let it run for a hundred packets, and essentially no packet loss. But something’s just not right. When someone else is streaming a movie, or a machine is pushing a backup up to a remote server, it all falls apart. That’s bufferbloat, and it’s actually really easy to do a simple test to detect it. Run a speed test, and run a ping test while your connection is being saturated. If your latency under load goes through the roof, you likely have bufferbloat. There are even a few of the big speed test sites that now offer bufferbloat tests. But first, some history. Continue reading “Bufferbloat, The Internet, And How To Fix It” →