Is 35Mbps RS485 communication possible?

[olejl77]

When reading Wikipedia about RS-485 it say that it offers data transmission speeds of 35 Mbit/s.

I haven't done any electronics design before, and are struggling to see how things are working together. I have a microprocessor, and want to be able to communicate at 35Mbps RS-485.

Micro-processor AT32UC3A0128, and one IC which seem to be able to do the job is MAX3469

Could I do this:

AT32UC3 uC <=== ? ===> MAX3469 <=== wire ===> MAX3469 <=== ? ===> AT32UC3 uC

How do I interconnect the Atmel processor and MAXIM IC?
What is the difference between UART and Tranceiver?

 

[tpetar]

Yes MAX3469 can presents nice speed of RS485.

See LTC1685 52Mbs in attachment.


The Practical Limits of RS485
http://www.dmx512-online.com/ddloads/RS485.pdf


http://www.lammertbies.nl/comm/info/RS-485.html

Noise is easily picked up and limits both the maximum distance and communication speed.

When the cable is twisted, we see that in some parts of the signal lines the direction of the noise current is the oposite from the current in other parts of the cable. Because of this, the resulting noise current is many factors lower than with an ordinary straight cable. Shielding—which is a common method to prevent noise in RS232 lines—tries to keep hostile magnetic fields away from the signal lines. Twisted pairs in RS485 communication however adds immunity which is a much better way to fight noise. The magnetic fields are allowed to pass, but do no harm. If high noise immunity is needed, often a combination of twisting and shielding is used as for example in STP, shielded twisted pair and FTP, foiled twisted pair networking cables. Differential signals and twisting allows RS485 to communicate over much longer communication distances than achievable with RS232. With RS485 communication distances of 1200 m are possible.

Differential signal lines also allow higher bit rates than possible with non-differential connections. Therefore RS485 can overcome the practical communication speed limit of RS232. Currently RS485 drivers are produced that can achieve a bit rate of 35 mbps.




How Far and How Fast Can You Go with RS-485?
**broken link removed**


RS485 Transceivers Operate at 52Mbps Over 100 Feet of
http://www.iele.polsl.pl/elenota/Linear_Technology/dn168f.pdf


RS485 Fast Signaling Texas Instruments demonstrated 100Mbs
**broken link removed**

 

[olejl77]

Hi and thanks for the thorough reply.

Still have a few things that I don't understand.

1. When should I use a Tranceiver and when should I use an UART?
2. How do I connect it the e.g. tranceiver to the processor? Do I connect to a GPIO pin and create a "driver" in SW?