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6678 NDK UDP: Maximum bytes(8192) of UDP Receive limit and Real received bytes

Wenjie Ji
Prodigy 110 points

Hi,

The version I used

CCS version: CCS_5.0.3 MCSDK version: mcsdk_2_00_07_19 NDK version: ndk_2_20_06_35 Board version: TMDXEVM6678LE

I use the usage in the mcsdk-----Helloworld_evmc6678l.

I know it could set the UDP receive limit by writing the following codes:

     // UDP Receive limit

    rc = 8192;

    CfgAddEntry( hCfg, CFGTAG_IP, CFGITEM_IP_SOCKUDPRXLIMIT,

                 CFG_ADDMODE_UNIQUE, sizeof(uint), (UINT8 *)&rc, 0 );

When I send several data (36*36 gray level image or less than it), it can obtain(can reach the breakpoint in the following picture)

But when sending data (40*40 gray level image or more than this), the program couldn’t reach the breakpoint.

 

According to this condition, I guess there is something wrong with UDP Receive limit or memory. But I don’t know how to alert the setting of the data-received size.

Who did it before, could help me to solve it?

  • 0
    Mastermind 6670 points

    Hi,

    The ethernet MTU (maximum packet size) is  1500 bytes (UDP payload is a bit less, due to the bytes used for the UDP header), so pay attention in increasing the UDP maximum packet size. Size greater then 1500 bytes are possible using the so called jumbo packet, but this not always supported.

    UDP can theorically send up to 64K in a packet, but it depend on the transport layer (in this case ethernet) and a signel packet could be broken in multiple messages.

    The TI NDK can support jumbo packet but I don't know if it require recompilation or if they are supported by default. Also, the "other side" have to support jumbo packets.

    Once I tried to send jumbo packet under Windows, but it doens't work.

  • 0 in reply to Alberto Chessa
    Prodigy 110 points

    Hi,Alberto Chessa

    Thanks for you reply.

    I know a little about jumbo packet and I'll try it again.

    Thanks again for your  suggestion. If I work it out, I'll show it.

    Wenjie