[En-Nut-Discussion] Time Calculation for TCP Data Transfer (want to reduce response time)

Brett Abbott Brett.Abbott at digital-telemetry.com
Sun Jun 24 11:02:37 CEST 2007


You might find it useful to use wireshark ethernet analyser 
(www.wireshark.org) to track the packet times - this will at least help 
you to see where some of the delays are and where you most need to focus 
your efforts.  (If you are running on a PC that is not the one connected 
to the micro-controller, dont forget to use a hub as switches will 
suppress the ethernet traffic not destined for the wireshark PC).


> Hi
>   I have a client on PC and TCP Server on AVR Microcontroler (using Charon-2 Board).
>   I want to calculate the time for 128 Bytes to send.
>   1) i have used NutGetMillis(), NutGetTickCount().
>       I have called NutGetMillis() before sending 128 Bytes and after "fwrite", i again called      NutGetMillis() to reterive the value. The value i got before sending the data is same as after sending the data. After some time when i keep sending and receiving there comes a difference of 1ms. This thing is from microcontroller side (ie time for microcontroller to send 128 Bytes of data)
>   2) Now i have used oscilloscop to measure the time.
>       The time to send the command from PC and the reaction of microcontroller(to send 128 Bytes) is taking 50ms.
>   3) if i am using for loop on pc side to send and receive data 5 or more times than 
>       "time to next transfer is 400ms". 
>   The problem is that i want short response times. how is that achievable.
>   If any one need source code i can post it as well.
>   Thanks
>   Bye
> ---------------------------------
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Brett Abbott, Managing Director, Digital Telemetry Limited
Email: Brett.Abbott at digital-telemetry.com
PO Box 24 036 Manners Street, Wellington, New Zealand
Phone +64 (4) 462-3439  Mobile +64 (21) 656-144
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