Any current equivalent for AMD's TAXIchip?

[Andrew Gabriel]

I used the AMD TAXIchip some ~14 years ago, but it seems to
have been obsolete for some time now. Is there a current
equivalent? I was looking to replicate 8 LED indicators
and it would be nice to use fewer than 8 interconnect wires
over the distance with a one-chip solution at each end.
I don't actually need anything like the frequency response
of the TAXIchip -- 10-20Hz per LED would be enough.

--
Andrew Gabriel

 

[Mike Harrison]

On 18 Oct 2004 19:27:19 GMT, andrew@cucumber.demon.co.uk (Andrew Gabriel) wrote:

I used the AMD TAXIchip some ~14 years ago, but it seems to
have been obsolete for some time now. Is there a current
equivalent? I was looking to replicate 8 LED indicators
and it would be nice to use fewer than 8 interconnect wires
over the distance with a one-chip solution at each end.
I don't actually need anything like the frequency response
of the TAXIchip -- 10-20Hz per LED would be enough.

A small PIC or AVR at each end would probably be the cheapest, and do-able with 3 wires (2 with some
external passives - modulate the data as a ~100mv steps on the power line, detected with the ADC.
Depending on how many interconnects you can live with, you could use a PIC/AVR on one end and a
shift-register on the other.

 

[Hal Murray]

I used the AMD TAXIchip some ~14 years ago, but it seems to
have been obsolete for some time now. Is there a current
equivalent? I was looking to replicate 8 LED indicators
and it would be nice to use fewer than 8 interconnect wires
over the distance with a one-chip solution at each end.
I don't actually need anything like the frequency response
of the TAXIchip -- 10-20Hz per LED would be enough.

LVDS and CPLD/FPGA? I'd probably use Manchester encoding
rather than 4B/5B. That needs more bandwidth on the wire
but is trivial to encode/decode and has a 50/50 cycle.

[Wow, old memories. I've got a couple on an old board.]

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[crzndog]

National Semiconductor's Channel Link Devices would be an excellent choice.
DS90CR215 and 216 would work well for you. I've had these devices working
in many projects and they are very reliable.

Things to really watch out for:

1) Make sure you use twisted pairs inside a sheilded cable
2) Make sure the shield connects to digital ground on BOTH sides of the
circuits you are connecting together. The Channel link parts need good
grounding as the are differential w.r.t. GND. Please ask National for a
design guide or read their on-line materials as the cover this quite well.
3) If you are doing high-speed bus work you should also look at using the
equalizer option on some of the parts. This basically changes the waveforms
of the signals so that they look clean at the receiving end.
4) When testing, measure the signals at the receivers only. Anywhere
else on the transmission line will look like garbage.
5) Have some really good decoupling with the parts since they have built
in PLLs.

These things are way better than the TAXI chips that I (we) have all used in
the past. They are lower power and also have low radiation issues (EMI
compliance is good) due to the twisted pair nature of the siganlling.

BTW I used the TAXI chips on a 3DO Games development system way back when!

Gareth.

"Andrew Gabriel" <andrew@cucumber.demon.co.uk> wrote in message
news:cl15en$rqe$1@new-usenet.uk.sun.com...

I used the AMD TAXIchip some ~14 years ago, but it seems to
have been obsolete for some time now. Is there a current
equivalent? I was looking to replicate 8 LED indicators
and it would be nice to use fewer than 8 interconnect wires
over the distance with a one-chip solution at each end.
I don't actually need anything like the frequency response
of the TAXIchip -- 10-20Hz per LED would be enough.

--
Andrew Gabriel