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Test the sending rate of UDP packets in Pa_emacexample

feng
Intellectual 270 points

Hello, experts.

My Purpose: Use pa_emacexample demo test  the speed of UDP packets send.

Test conditions: In the Cpsw_SingleCoreApp () task ,continues call SendPacket () function.

Modify pktMatch [] array length are 8242 bytes, and set the mtu to 10254 in Init_Cpsw () function.

Testing tools: wireshark.

Phenomenon:

1 first simulation.

a. If it is the first execution of the power (Every time execution the gel files) will always print "No Tx free descriptor. Cant run send / rcv test".

b. If each click "System Reset", and then load the program runs, it will not print. And the transmission speed faster than a case. (Via wireshark to know).

Later, find the difference between the two cases.a case, PLL1_PLLCTL and PLL1_CMD the last bit is 1. b case, PLL1_PLLCTL and PLL1_CMD the last bit is 0. PLL1_PLLCTL the last bit is the PLL enable bit. 0 = Bypass mode,1 = PLL mode. Therefore, the frequency is not the same in both cases. So be compared through boot from nand.

2.boot from nand

a. PLL1_PLLCTL and PLL1_CMD the last bit remains unchanged(gel file is set to 1), After running ,print” No Tx free descriptor. Cant run send / rcv test ". Wireshark packet test the speed and the statistical results are as follows:

b. In EVM_init () function, set PLL1_PLLCTL and PLL1_CMD the last bit is 0. Others remain unchanged. At this time the main function serial port does not print any information. Wireshark test speed and packet counts as follows:

I think, print “No Tx free descriptor. Cant run send / rcv test ". Because of slower network port sends ,and the descriptor has not recovered, however the application executes faster, so not get the descriptors.

After modify PLL1_PLLCTL and PLL1_CMD the last bit to 0, the speed difference of about two times.

My question:

1.Modify PLL1_PLLCTL and PLL1_CMD the last bit is 0, disabled the PLL mode and enable the bypass mode, it should be said is to reduce the frequency of the system, but why the speed of send is too fast? What causes it? I think it is not normal.

2.I think 2-a is normal, but why only 250Mbit/sec transmission speed about it? As has been printed "No Tx free descriptor. Cant run send / rcv test". So I think it does not matter to the CPU, and network port transmission speed of a relationship, if I want to send UDP packets to enhance pa_emacexample speed, how should I do it?

3.why after set PLL1_PLLCTL and PLL1_CMD the last bit is 0,the serial port does not print any information?

I hope to get your help ,thank you.

 

  • 0
    TI__Mastermind 30825 points

    In Bypass mode the device is getting clocking rates that are at the speed of the input clock.  On the EVM I believe this is 100MHz.  Many of the peripherals will not work with the core clocked at this frequency.  Subclocks from this are provided to various peripherals and logic inside the device.  The NetCP for example will not operate correctly below the device operating at 600MHz.  

    The Bypass mode is only there for initial internal BootROM execution.  The BootROM itself will enable the PLL's based on BOOTMODE[12:10] pins (unless using I2C or SPI boot in which case the I2C or SPI EEPROM would include the values for PLL configuration.)

    When using CCS/JTAG you will need to use a GEL file to program the PLL.

    Best Regards,

    Chad