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Introducing (and interest check) AirTalk: Wireless plug-and-play LocalTalk dongles

LaPorta

Well-known member
Don’t mind me, either: when it comes to software, I’m pretty much just the guy who says “wouldn’t it be cool to…” with no idea of what it would entail or how hard it would be.

:p
 

cheesestraws

Well-known member
More good news: the cheaper RS485 transceiver chip I was hoping to use I just tested and it works perfectly, at least in this rather dodgy breakout arrangement:

66198813533__22671985-38B0-44CC-A909-833FE750C259.JPG
 

cheesestraws

Well-known member
Some updates, for interested folks:
  • I've done a lot of performance testing. With two AirTalk dongles and two PowerBooks, the bulk transfer speed (as measured by a big AFP transfer) is about 75-80% of the speed one gets over a localtalk cable between those two computers. I'm fairly sure this is due to WiFi being having much higher latency than LocalTalk, and also being less consistent in round trip time. I think this is a reasonable tradeoff for the extra flexibility, personally, but I'm interested in what other people think. I haven't done any testing with > 2 dongles yet, on the basis that I only have built two dongles.

  • I've finished a provisional schematic for the production version of the dongle, which I've attached below. I'd like feedback/critique on this, please: @bdurbrow if you have time I'd especially like feedback/critique from you, please, since you've been designing the Pi hat. Anyone else wants to join in please do. For the avoidance of doubt, this schematic should be considered CC-NC licensed, and also provisional. You're welcome to build one based on this if you really want to, but I'd suggest waiting until it's finished.

  • I've also got an even more provisional PCB layout based on this schematic, which I'm not going to post here yet, as it's too close to being totally unfinished.

  • I've added the "only relevant nodes" forwarding filter, which should significantly improve performance in situations with three or more AirTalks in play, or two AirTalks and a bridge. Can't really test that yet, because only two exist in the world.
 

Attachments

  • airtalk.pdf
    153.7 KB · Views: 39

shadedream

Well-known member
This looks great Cheesy. Skimmed through the pages and didn't see specific wifi details mentioned. I assume these are probably using 2.4ghz, but what authentication protocols does it support?
 

cheesestraws

Well-known member
I assume these are probably using 2.4ghz, but what authentication protocols does it support?

Yes, the ESP32 is 2.4GHz only. WPA/WPA2/WPA3 I believe should work as it currently stands. My network at home is WPA2. I don't believe it supports WEP, and I don't want to support WEP anyway.

The stack also supports WPA2 Enterprise but I haven't hooked that in because it seems an awful lot of work for something that probably nobody will use. If people do want that, well, that'll be a bit of a pain :D.
 

just.in.time

Well-known member
@cheesestraws These look awesome! Would be great for old local talk games (Super Maze Wars off the top of my head) and also moving files between multiple devices. I’m definitely interested in getting some of them.
 

CC_333

Well-known member
I don't believe it supports WEP, and I don't want to support WEP anyway.
That's fair (WEP is a waste of time anyway), but you can at least support the option of using an open (unsecured) network, right?

Believe it or not, there do exist places on earth where nobody's around to hack into one's weakly secured WiFi network, and, at least in my experience, having an open WiFi network available is useful for older PowerBooks and such whose support for WPA1, let alone 2 and 3, ranges from weak under Mac OS X to practically nonexistent under OS 9.x.

c
 
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LaPorta

Well-known member
I just had a thought that might be the equivalent of a brain fart, but...

Let's imagine this scenario:

You have a wireless network set up - a few new Macs via AirPort/Ethernet.

You have an old-school AppleTalk network set up with Macs that have no ethernet capability, just Printer Port-based PhoneNet boxes all strung together. You have no iPrint or LocalTalk to Ethernet bridges or any of these other things that are, to be fair, increasingly rare.

You get two of these AirTalk dongles. The newer Macs either don't have serial ports, or if they do, they can't use both ethernet and serial port AppleTalk at the same time.

You could hook one dongle into one of the ethernetless Macs to connect it to the wireless network...but then it would leave the PhoneNet chain, breaking its connection with the other ethernetless Macs.


The main gist of what I am getting at is this: with the way these work, and how old-school, OS 9 and older networking works, I am not sure that there would be a way to actually bridge these two networks together.

Unless...

Perhaps in the future there would be some sort of way to make these dongles function as one jack of a two-jack PhoneNet adapter. That is, one side would be a phone jack for wiring into the next PhoneNet Mac, and the other "jack" would be the AirTalk adapter. This way, you could bridge both networks at the same time. I am not sure how difficult it would be to pass the signals along and make it think that AirTalk is a physical phone wire (although I assume how this works, it already does somehow).

Obviously this is like a version 2.0 thing or something....I just thought that this could A. Make it possible to blend networks using just LocalTalk cabling and wireless/ethernet, and B. not create an "odd man out" scenario as is described above for a Mac needing to pick one network modality or the other at a time.
 

cheesestraws

Well-known member
Perhaps in the future there would be some sort of way to make these dongles function as one jack of a two-jack PhoneNet adapter. That is, one side would be a phone jack for wiring into the next PhoneNet Mac, and the other "jack" would be the AirTalk adapter. This way, you could bridge both networks at the same time. I am not sure how difficult it would be to pass the signals along and make it think that AirTalk is a physical phone wire (although I assume how this works, it already does somehow).

You can already do this, though I haven't tested it very hard yet. The box just has an 8-pin mini-DIN which you can either use to connect to a mac with an Apple serial cable, or you can plug a PhoneNet or LocalTalk box into it and attach it to an existing network, at which point all the Macs on that network can use it (though of course there will only be so much bandwidth to go around). Here's a diagram:

Screen Shot 2022-01-02 at 09.48.03.png

Another way of thinking of this is that it sits on the network pretending to be all the wireless Macs, changing hats really fast as network packets are processed.

You could hook one dongle into one of the ethernetless Macs to connect it to the wireless network

Don't forget that at the moment this wouldn't give the ethernetless macs access to service provided by the ethernett-y Macs. It's just like a long LocalTalk cable. Working on that :).
 

LaPorta

Well-known member
Nice! I didn’t realize it would function like that! Ok, that definitely answered a big question for me!
 

cheesestraws

Well-known member
That's fair (WEP is a waste of time anyway), but you can at least support the option of using an open (unsecured) network, right?

There is support for open networks in, but I haven't tested it and don't intend to encourage its use. Part of the point of this is to decouple the wifi from the actual machine, so there's not a huge amount of point in attaching this to a "vintage computing" open wifi AP anyway. Remember it isn't a LT <-> Ethernet bridge.
 

Cory5412

Daring Pioneer of the Future
Staff member
Just had a chance to read all the updates on this, this is really great work, thank you for doing and sharing this!
 

cheesestraws

Well-known member
I think I've done most of the software work I wanted to do aside from some tidying, and found a couple more bugs that I hadn't been aware of. Now that I've fixed those, this works properly with routed traffic. Here's Mini vMac talking to my real network through an AirTalk plugged into the LocalTalk port of my Apple Internet Router box.

Screen Shot 2022-01-03 at 16.14.34.png

I've ordered some first iteration PCBs—thanks to @demik and @Phipli who looked over the schematics for me—and now mostly I'm sitting here grumpily waiting for them to arrive...
 

bdurbrow

Well-known member
Uhh... well... first, the disclaimer: everything I know about hardware design is self-taught; so it's quite possible that I'll miss something obvious to a real electronics engineer... but...

The schematic looks OK to me... obviously, as you have a couple on your bench working, it's at least functional. If you post gerbers (or PDF files of the layers, etc) I'll have a look at them also...

If there's enough room, on the next rev of the board, I would suggest routing any unused pins on the ESP32 to a header pad (which can be left unpopulated when constructing it) so that any future ideas/hacks/add-ons can be accommodated. I'd also put power, ground, and reset lines on that header pad.
 

cheesestraws

Well-known member
Quick opinion-seeking: would people prefer to have this with a case, as a bare board, or to have the option? A decent quality case of the size I'd need would add around £5, so taking the whole thing up to ~£25.
 

btse

Member
I'll vote for case or at least with option.

I'd also like to express my intrest in getting one, if you have any unclaimed remaining.
 
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