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  • Uart speed

    Using the point to point code supplied with portal has anyone managed to get the SNAP UARTS to run above 19.2/20K or is the use of '1' for 115,200bps in 'intUart' just a typo? We think we're just missing something (apart from the data) but what...

  • #2
    "1" is not a type-o. Snap uses 16-bit integers, so you can't pass 115200 in as a parameter. That would be larger than would fit in a 16-bit integer.

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    • #3
      Uart speed

      Thats fine - thanks.

      The only trouble then is that between 20K and 115K we're unable to get a a pair of SNAPS to transfer data. Given the little bit of sample code works fine below 20K whats the secret to higher speeds? We have 6 modules and they all do the same thing so you'd have to think its settings not the kit.

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      • #4
        It is certainly possible to connect a serial device that operates at a 115.2K baud rate without that being the max. sustained RF throughput. i.e. The two devices must talk at 115.2K to hear each other properly, but do not constantly send data at this rate. The initUart() setting relates to the serial connection and not to the radio or sub-system.

        SNAP has been ported to a number of different types of technologies, both RF (2.4 GHz, 900MHz, sub-GHz) and other mediums (Serial, TCP/IP, PLC). Some of these technologies provide a higher throughput than the original RF100 RF Engine.

        That being said, Synapse will very shortly release an RF200 module that implements a 2MB radio data-rate at 2.4 GHz. This device should be able to support the serial throughput you are looking for.

        The max tested throughput of an RF100 RF Engine was 38.4K (point-to-point datamode scripts).
        sigpic
        Proven Solutions for the Internet of Things
        www.synapse-wireless.com

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        • #5
          Originally posted by cycom View Post
          The only trouble then is that between 20K and 115K we're unable to get a a pair of SNAPS to transfer data.
          To clarify does it transfer any data for you at those speeds or just not at the full sustained rate (as explained by JHeath above)?
          --Mark
          Synapse Design Engineer

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          • #6
            Uart speed

            Hi guys(?) - thanks

            We looked back at the spec sheet and, as you'd know, it states a 250Kb RF rate so that coupled with the 115K UART led us to think that even with the MESH o'head you'd get the 115K with room to spare - obviously not so....

            Re the 115K you'd have to say not many people would want to connect at 115 to send at 30..

            We do have our own 7GHz unit which will run this speed+ but we're looking for a more 'conventional' solution for this development.

            If the 2Mb unit is close we'd be happy to keep SNAP in our development mix.

            Re the transfer speed using our live data we couldn't see any transfer above 20K. We're just in the process of setting up a new link with the BERT to see what speeds/error rate we actually get. We'll give you a heads-up when its done.

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            • #7
              When you perform your test, there are a few NV Parameter settings that should help increase serial throughput.

              Most depend on the format/timing of the data you are attempting to transmit.

              NV13 - Buffering Threshold (in ms):
              This represents the time the system will wait from receiving the initial character before beginning the forwarding process. It can be more efficient to wait for a little longer than the 5ms default and send more per packet (fewer, bigger packets vs. a number of smaller packets). This depends on how the BERT tester is configured.

              NV14 - Buffering threshold (in bytes):
              This is how much data is allowed to accumulate before beginning the forwarding process. Usually, the system has already sent the data before it reaches this threshold, but the default of 75 bytes can be lower if the other triggers (NV13 and NV15) are not the impetus for the data to be sent.

              NV15 - Inter-Character Timeout (in ms):
              This is the time to wait between individual characters before forwarding data. It defaults to 0 (disabled), but can be enabled for in order to send a number of smaller packet transmissions rather than waiting to collect larger strings. Very much related to NV 13.

              NV 18 - Collision Avoidance (enable/disable):
              This is a delay that is added before packet transmission. It is enabled by default and is used to make sure multiple nodes do not receive the same multicast message and respond all at once. If you only have a single point-to-point network this delay is not necessary.

              As always, the SNAP Reference Manual has more details regarding these settings.
              sigpic
              Proven Solutions for the Internet of Things
              www.synapse-wireless.com

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              • #8
                Uart speed

                Thanks JH.

                We're tinkering with these now but its early beer o'clock today (Friday) so it looks like we won't get a run on it 'till next week.

                Do you have a delivery date for the 2Mb version?

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                • #9
                  Planned roll out is to begin next month. Future Electronics should be your source in Australia.

                  Enjoy your Friday and enjoy a Cooper's for me.
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                  Proven Solutions for the Internet of Things
                  www.synapse-wireless.com

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                  • #10
                    Do you have a delivery date for the 2Mb version?
                    We're working through getting FCC certification for the new 2Mbps SNAP Engine (it's called an RF200 by the way).

                    Normally FCC certification is handled by the actual chip vendors, not us, so we're still working through the process.

                    The RF300 (900 MHZ among others) is also undergoing FCC compliance testing.

                    Once that is done, we will ramp up volume production of both types of modules.

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                    • #11
                      Uart speed

                      JH,KB,

                      Its taken a while to respond to your last post. We had a bit of a play after we spoke using the BER but even with the 'tweeks' we weren't able to do much better than about 24/25K. We've had 6 of your 200PD1s on order since Aug but Future are now advising a Jan '11 delivery so I'm guessing testing had a few bumps.. Hopefully, as you say, we'll be able to get the throughput we're looking for with the 200.

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                      • #12
                        So for the rf200s, what is the maximum sustained UART throughput at each of the 4 radio data rates (i.e. 250k / 500k / 1M / 2M)? Is this data available anywhere?

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                        • #13
                          And also, what is the respective receiver sensitivity at each of those data rates? Datasheet says -103 dBm @ 250k but what about @ 500k and above?

                          Thanks,

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                          • #14
                            Anyone ?

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                            • #15
                              bump ,

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