AT91RM9200 synchronous serial to ethernet

May 18, 2004 2 Replies
S

Hi



I'm looking into a design to convert from synchronous serial interface (SSI) to ethernet. The ethernet connection will be a direct, point to point connection and will probably use UDP. I have looked at the data sheet for the AT91RM9200 and it seems as though it may work. I'm new to ARM devices and also to embedded ethernet and would greatly appreciate if anyone could answer the following questions:


  1. What sustained data rates are possible when transferring data from the synchronous serial controllers to ethernet?
  2. Is it feasible to implement this functionality without running an OS on the processor?

Many thanks



Sam Duncan


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U

You have a limit in the AT91RM9200 SSC to (IIRC) Bus Clock / 4. Since the Bus Clock is typically 60 MHz, you would end up in 15 MHz.

Most efficient is if the SSC can store packet into the 16 kB RAM which are already prepared for transmission using UDP. I.E you allocate an area with a fixed size data. Precede that data with the UDP header, and after the data, then you have the UDP trailer. I do not know what throughput you get, because you need to do CRC calculations etc. Check the ROM services for useful stuff like the CRC tables.

Best Regards Ulf at atmel dot com These comments are intended to be my own opinion and they may, or may not be shared by my employer, Atmel Sweden. > Many thanks > > Sam Duncan
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J

My data says MCLK/2 >= BitRate >= MCLK/8190 Nailing down MCLK is not so easy, I found yesterday tCHMCK >= 2.2ns (half clock), but today I see another

1/(tCPMCK) Master Clock Frequency
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