DIY Localtalk - Ethernet converter

[techknight]

RS-485 is just the interface, half-duplex at that. You wanna speak SDLC over RS-485

Woudl be nice to have a dongle that converts SDLC to UART. This would allow bluetooth and wifi, or any other RF serial interface modules to be used for localtalk. like xBee.

 

[bbraun]

Allow me to rephrase: SDLC is not a problem, but to want to implement SDLC on top of RS485 yourself instead of just using an $8 part for a low volume hobby run where you're donating your time, you'd have to really enjoy implementing SDLC.

 

[techknight]

Naw, i wouldn't do that. I would just use a chip that supports SDLC. The microcontroller itself could control the transport for the other end.

 

[bd1308]

I'm restarting work on this. There have been plenty of implementations of this already, and the protocol is seemingly simple to bitbang. In fact, most implementations of this are essetntially bitbanging at the right speeds to perform the magic things.

There's an arduino with USB host capability that I'm in the process of acquiring. I've just moved and settled in and finally moved my computer stuff into its permanent home, so forgive me for taking so long on this.

Essentially, there's an USB stack for the arduino that allows for controlling a keyboard and mouse. The other end would just bitbang everything to a ADB keyboard and mouse.

I've already had limited success with speaking ADB via an arduino and there's plenty of reverse implementations of this on the internet.

Everything will be opensourced, and should be possible via an arduino.

 

[mactjaap]

This is really great news bd!

I was planning to move my MacIPgw virtual machine to a more permanent solution on a Raspberry Pi......but that is without LocalTalk, because I'm not capable of doing that. So if there would come an open source Localtalk solution with Arduino it would be really great.

If I can help with something, please let me know.

I will follow this tread carefullly.

 

[dougg3]

I was actually thinking of the smaller-cheaper "Printer adapters" (Ala, AsanteTalk, Farallon iPrint LT, etc) rather than the more heavy duty iron when I said it

After you mentioned that, I wanted to know too. I ripped open my Farallon EtherWave Printer Adapter to get some pictures of the PCB for a rough idea of the architecture. I wish these pictures (particularly the second one) were better, but they're a start...





Looks like the LocalTalk portion (and probably the main firmware?) is done with the Zilog Z8018110FEC. The Z80181 is a microprocessor with a Z85C30 SCC built in. I've also identified a Hynix 32KB SRAM chip. I didn't want to tear off any of the stickers, so I'm not sure about some of the chips. I bet a good chunk of the rest of the chips are for Ethernet. I would assume the chip with the 34F939 sticker is going to be an ethernet controller.

If anyone wants better detail I can reopen it and take pictures with a real camera...

 

[techknight]

So I guess the best way to approach this is using an SCC/SDLC compatible IC. then a microcontroller/processor to handle everything else.

 

[cb88]

That macipgw looks pretty handy ... Does that work with localtalk printer bridges? I could probably set it up on my transmeta laptop which I forget running for months on end anyway ;-) .

I've been hunting for ways to get my SE/30 and Plus on the net this looks promising!

 

[mactjaap]

@cb88

You can use the MacIPgw virtual machine with a simple LocalTalk bridge. I will test it also with the LocalTalk Bridge control panel of Apple.

Have a look at viewtopic.php?f=29&t=22036

If you have any question..please let me know!

 

[techknight]

Here is a document I found, Its a Zilog application note and explains how to implement localtalk using their SCC, Including the source code

http://www.zilog.com/appnotes_download.php?FromPage=DirectLink&dn=AN0064&ft=Application%20Note&f=YUhSMGNEb3ZMM2QzZHk1NmFXeHZaeTVqYjIwdlpHOWpjeTk2TVRnd0wyRndjRzV2ZEdWekwyeHZZM1JoYkdzdWNHUm0=

 

[Bunsen]

Now that ^ is a find. What language/architecture is the source code?

The Z80181 is a microprocessor with a Z85C30 SCC built in.

Also good to know. Mouser and Zilog themselves appear to have them in stock.

If anyone wants better detail I can reopen it and take pictures with a real camera...

Got a scanner?

 

[dougg3]

Got a scanner?

Absolutely! I just scanned both sides of the PCB at 1200 dpi and ended up with 25 MB images. Converted them to a low quality JPG and got them down to about 500 to 700 KB. I went ahead and hosted them off-site...if you'd rather have them hosted here that's fine too.

http://imgur.com/a/HmkBE

If you hover over the image and go to actions, you can get the full resolution images at over 4000x4000 pixels.

 

[mactjaap]

Any news on this subject?

We have seen some success stories on the board lately. I'm thing of the Floppy Emu and the SCSI2SD project.

Would be great if we could get the DIY Localtalk - Ethernet converter to some kind of prototype!

 

[bd1308]

Easily done with a raspberry pi. Convert the serial output to RS232, and have a service that listens to the serial pins on the r-pi and translates them to a virtual mac serial port. Done.

Everything already exists at a software level --- netatalk for appletalk, the serial port driver for a real mac serial port, and of course linux on the r-pi. The only part needed is gluecode to convert the RS232 signals to a virtual localtalk port

That part is easy --- question is....is it cheating (too easy?)

 

[bd1308]

Haven't given up on the BTW. If someone manages to have more spare time than I do feel free to run with this lol

I still need to re-cap a bunch of stuff. At the moment I seem to lack time *and* money.

 

[bd1308]

OK. Totally glazed past the part where chips are available that contains the SCC built in ---- *thats* where I wanna be.

With the raspberry pi being way more powerful, shouldn't we consider doing this in software (which I'm much more familiar with).

I wanted to get involved in a hardware project to teach myself hardware things though, so maybe I can start buying stuff

 

[tashtari]

Just in case there's anyone watching (or finding) this thread from nine years ago who hasn't heard of it yet, I think what's been talked about here has been accomplished with TashTalk:

TashTalk: Single-Chip LocalTalk Interface

While I've been mostly talking about this project in the IRC channel, it occurred to me that 68kmla has (or, by some definitions, is) a forum, so I thought I'd better make a thread about it to document it and see what folks think. Introducing... TashTalk! Elevator Pitch It's a LocalTalk...

68kmla.org

GitHub - lampmerchant/tashtalk: An interface for Apple's LocalTalk networking protocol.

An interface for Apple's LocalTalk networking protocol. - lampmerchant/tashtalk

github.com