Some sites shadowban .tk, Reddit probably still does. Search engines probably downrank it. That's because it's free and has been used for a lot of spammy stuff.
This makes it harder for people to share and harder for people to find. That might just put a damper on your hobby, but it might also mean you won't get random emails about jobs you might want. (If you're interested in that.)
I only mention it because I learned that the hard way many years ago.
https://tailsteak.com/archive.php?num=388
“tailsteak.com
Alright, so I'm finally fed up with Tokelau.
Don't get me wrong, it's a nice island, but they just aren't answering my mail.
I suppose most of you have noticed, by now, the fifteen-second ads that present you with beautiful women and fish when you surf to tailsteak.tk. Those are not my ads. I do not obtain revenue from them. Tokelau's domain name referral service just started putting them up there without so much as a by-your-leave. I have contacted their tech support and enquired if, perhaps, they might consider removing them for customers willing to pay a certain amount. They have not responded.
Of course, I have had access to tailsteak.com for some time now. So henceforth, I will be directing my viewers there. It's the same site, the same host, and, in truth, the .tk address has been sending you there for months. But now it's official. Note the change in title graphic:
tailsteak.com”
Although I think .icu and .xyz are far bigger offenders than .tk these days.
If we think about potential dollars, though:
The bottomless pit isn't very deep, it's a few dollars a year.
If it nets you one single short-contract offer (nevermind a job) or worthwhile contact because someone found your work, it'll pay itself off many, many times over. Let's say one person found him and offered him a $3000 contract to do some electronic thing for a week, well, then the cost of the domain and hosting won't matter for the rest of his life.
The mere fact that this guy has an oscilloscope out means he has skills that someone might want to contact him about in relation to his blog.
Limiting yourself for want of a $10/year domain name is probably not a great idea, and again, it's something I learned the hard way.
It has a nice high level diagram of what each group of TTL chips is doing too:
https://lh3.googleusercontent.com/-DpUyda3g2Yk/WgB7G_7o54I/A...
3Com 10Mbps Ethernet 3C500 aka IBM Ethernet (IE) aka EtherLink from October 1982
https://static.wixstatic.com/media/a03cac_005e3e9eb62b47c292...
>"According to the 10BASE-T spec, each frame starts with a fixed synchronization sequence of 64 bits, first 62 of which are alternating ones and zeroes and the last two are ones."
I believe the intention of the "preamble" is to provide clocking and synchronization for the circuit so that it knows where to find the start frame delimiter and subsequent fields. Is that correct?
My other question is at what point does the circuit drop frames that are not intended for it? Does that happen in layer 1 or layer 2? I realize this happens less in modern switched Ethernet networks but it is still possible for a host to get an Ethernet frame for where the destination MAC address does not match any of those burned-in addresses on the Ethernet adapter. Does the transceiver always read the entire Ethernet frame even when the destination MAC address field it reads is incorrect? The maximum Ethernet frame size is 1518 bytes which seems like a lot of data read if the MAC address is not valid for the host.
Offloads such as this or other more advanced ones are implemented as optional hardware features (if at all) controlled by upstream signaling. This is usually a driver signaling things over a PCIe bus on modern systems but it can be anything including just "upstream logic gates". That way if it's a normal client-only PC not running e.g. Wireshark or VMs the CPU doesn't have to be interrupted for the types of traffic you mention but the other use cases can still work too.
>"Imagine you had 2 transceivers you wanted to bridge - if the transceiver dropped all unicast MACs but its own indiscriminately then it would not function properly"
I'm not understanding why bridging makes a difference. In the case of a bridge a host would send out a broadcast i.e a frame with destination MAC ff:ff:ff:ff:ff:ff which is valid for all Ethernet adapters, this is similar whether it's a switched or bridge network no? Maybe I'm missing something obvious?
>"Offloads such as this or other more advanced ones are implemented as optional hardware features (if at all) controlled by upstream signaling."
Which offloads are you referring to here? Just general TCP offload engine stuff? How does that relate?
My circuit doesn't drop any frames, it simply converts serial Ethernet signal to SPI. FCS and MAC checking is done in software after receiving the whole frame.
You absolutely can get frames not addressed to you. Wireshark lets you do that. I debugged my adapter this way: I connected it to a dumb switch together with my computer and ran Wireshark on the computer which captured all frames regardless of their intended destination. On Linux you can even disable FCS checking and receive all rubbish from the wire.
>"The first bit of an Ethernet frame is always one, which means there might or might not be an extra edge in the beginning depending on the idle state of the amplifier. This extra edge, if it comes, needs to be filtered out."
Practically speaking what is the cause of the "extra" edge here? Would it be that the last bit of the FCS from the previous frame caused it to be a 1 and then the transceiver is immediately getting another edge from a preamble on a new Ethernet frame? Or am I confusing bits and edges?
I would oppose a unit that starts with a prefix symbol (m=milli=0.001) on principle.
This makes building a data diode much simpler than I thought it needed to be. Thanks!
How long were they, and did they happen to coincide with short frames? It's been a long time since I've worked with 10M Ethernet PHY but I vaguely remember some non-standard implementations would lengthen the preamble instead of padding the "tail" of the frame.
IDK why something as fundamental as decoupling caps should be mentioned here at all though, anyone sufficiently knowledgeable to make use of this information would know that they're required already.
> Manchester code was used in early Ethernet physical layer standards
So, not in later standards?
More recent speeds all tend to use PAM4 encoding, meaning there's 4 voltage levels instead of 2! There's a great article on it here: https://blog.samtec.com/post/understanding-nrz-and-pam4-sign...
(What is the benefit of rhymes, meter, etc over using prose?)
Aside from this, Arduino shields for Ethernet are available for quite some time, but they often contain the more advanced chip than the atmega328p itself. Here OTOH the author builds from the ground up. Simply amazing!
That being said, I think most of the ppl that are serious about their arduino networking will use CAN as their network of choice (https://en.wikipedia.org/wiki/CAN_bus).
I had thought this was, "I simulated it in a high level HDL and synthesized it to gates".
No, this is... I built it with physical chips. Brilliant build and write-up!
Edit: This is beautiful for a second reason... The lack of regard for doing things "correctly". The ugly clock circuit is horrifically unreliable... But just reliable enough for it to still work.
It reminds me of Muntzing.
