Does anyone have a schematic for converting a 10baseT to 10base2? I need this for a project I'm developing as it only communicates to an old vintage hardware via a coax connection. I know there are boxes you can buy that do the conversion, but they are expensive and I'd rather put the circuitry within my project.

Hmm. I wasn't able to find much documentation on 10base2 (or IEEE 802.3) signaling. I would assume it's a pretty complicated circuit because you have to take bi-directional signaling and turn it into an RX and TX pair. I don't think it's trivial.

Terry You might be able to do something with: http://cgi.ebay.com/RTL8019AS-Ethernet-LAN-Module-AVR-PIC-ARM-MCU-/110500058337?pt=LH_DefaultDomain_0&hash=item19ba5114e1

This module is based on the Realtek RTL8019AS chip which supports 10Base2 and 10BaseT - there's a lot of information around on that chip.

best regards

Gerry

Hello Terry, on a old card the 10base2 is driven with a AM7996. It need Rx Tx and have a collision signal. The collision handling will be the problem if you try to use the 10base2 part of a old ethernet card. On 10base2 the transmitter is sending a packet to the cable and looks if the packet collide with a signal from a other card. On 10baseT the hub or switch is doing this.

regards, Peter

Right, Legacy Ethernet on coax uses CSMA/CD rather than switched ethernet on cat5/6. Switched ethernet cannot have collisions.

The original Ethernet concept was a coax cable daisy-chained to many computers with a vampire tap or coupler on the coax at each computer. There was "fat net", meaning 3/8 in. diameter coax (similar to RG8) for longer runs, and "thin net", using 1/4 in. coax (like RG58) for shorter runs. Photos http://en.wikipedia.org/wiki/10BASE2

Thanks guys. If I figure something out that works, I'll post it.

Does anyone have any info on how to interface with the chip module shown on the link that was given. I can't find anything on how an MCU or anything is supposed to interface with it. Lots of places sell it, but don't tell you how to use it. Also, on the link given, it doesn't seem to have a BNC connector.

I recall from way back that there were ethernet/coax (thin net, thick net) media converters to 802.3 twisted pair.

Hi Terry, you can see the BNC connector on page 7 of the AM7996 datasheet:

http://pdf1.alldatasheet.com/datasheet-pdf/view/55505/AMD/AM7996.html

It's called a media converter.

e.g. Look at auction 280630621418 on Ebay ( a Allied Telesis AT MC15 )

You could use a hub with both 10 Base-T and Ethernet 802.3 (BNC) support. These were common in the past and it should be possible to pick one up cheaply, e.g eBay: 200577250170 This should be suitable too: eBay: 110643683066 If you have access to a hub with AUI and 10 Base-T you can attach a media converter as mentioned in the last post to give a BNC output.

I have a media converter. They are expensive as we would need several hundred of them. I would need 2 media converters per processor hardware. The cost of the media converters would exceed the cost of the processor by many times. I need to build the 10Base2 hardware on the processor card for a significant savings.

Hello Terry, if you can get LevelOne LXT906 chips you can build a converter. Some chip broker sell this chip.

Thanks!!! This is EXACTLY what I wanted. I really appreciate your help.