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Round Trip raw messages timing in Transceiver mode

Eli Cohen
Prodigy 155 points
Other Parts Discussed in Thread: CC3200

Hi

I am new in the embedded business. I an trying to measure a message latency between two CC3200 boards. Because the two boards are not using the same time base, I had to perform, for the message, a round trip cycle. For that I modified and used the Transceiver example. One way works fine. In round trip the messages get stuck for a while before reaching their destination.  I have few questions:

1. Can I exchange messages between two boards configured as STATIONS. What would be the proper configuration ?

2. Do I have to use different channels or the same channel for all send/receive operations ?

3. Is their an example that demonstrate latency.

Thanks

Eli

  • 0
    Guru 21435 points
    Hi Eli,

    Could you explain what the over all goal/requirement is for your application? This may change my answers or provide ideas on better solutions.

    1. By using Station, the CC3200 device will connect to an WiFi Router/Access Point. So all communication will happen through this WiFi Router/Access Point. If your solution only need 2 CC3200 devices involved, you could use a combination of Access Point Mode and Station Mode, to create a 1 to 1 direct connections, you can also do the same by using WiFi Direct Mode.

    2. I am not very experienced with Transceiver Mode (so I am not sure about the next bit of advise), but it is my understanding that since you are establishing a connection using Station Mode (or other Modes) then the channel used will be the one established when your devices connect to the WiFi Router/Access Point

    3. Another potential method is to use a SNTP Server to get the time from the Internet, which then updates the RTC (Real Time Clock) of the CC3200. The accuracy of this method may not suffice, depending on the resolution you require. To see how you can do this, there is the get_time example in the SDK or my Starter Application on github (see the link in my sig below)

    Glenn
  • 0
    TI__Mastermind 26205 points
    Glenn, Thanks for the response.

    Few points I would like to add.

    2. If you are using transceiver mode you can use one channel for all send/receive. Please note only one transceiver mode socket can be opened at a time in. If you are not using the transceiver mode and connecting to an AP the station for the communication will be same as that of AP.

    3. Latency depends on many factors and is affected greatly by the environment of the test case. If transceiver mode is being used some of the packets can be dropped also.

    Regards,
    Ankur
  • 0 in reply to Ankur Baranwal
    Prodigy 155 points

    Glenn and Ankore, thanks for you responses

    1. The end application will involve 1 Access Point and surrounding stations transmitting audio in both directions. Timing is very important. I need to have message travel time around 1 Ms. I do not have the exact throughput but I assume less than average.

    2. For that I am using Transceiver mode, assuming no transmission overhead. Currently I am just testing the travel time. The two boards are connected to two computers in the same room. For all practical purposes this is not a heavy wireless environment. The current mode is Station to Station.

    3. But messages get stuck for a while somewhere and than arriving very late. I wonder if  (1) the Station to Station is a problem and may be I should use Access point to Station which is more natural or (2) Is there a potential collision problem between send and receive or (3) queuing problem. Can I control the IO queue size? I am not using any synchronization means since all actions are done sequentially on a single thread.

    Thanks

    Eli