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TMS320F28379D: Computation speed of the CLA

Part Number: TMS320F28379D
Other Parts Discussed in Thread: C2000WARE

Hello,

I have a question regarding the speed of the CLA.

 

The test program based on the cla_sqrt() project in the C2000Ware.

 

C:\ti\c2000\C2000Ware_2_00_00_03\device_support\f2837xd\examples\cpu1\cla_sqrt

 

In order to measure the speed I have extended the source files in the following way.

 

In cla_sqrt_cpu1.c:

 

   EALLOW;

   GpioCtrlRegs.GPDDIR.bit.GPIO97 = 1;    

   GpioCtrlRegs.GPDCSEL1.bit.GPIO97=1;    

   EDIS;

 

In sqrt.cla:

 

__interrupt void Cla1Task1 ( void )

{

//   __mdebugstop();

   GpioDataRegs.GPDTOGGLE.bit.GPIO97 = 1;

   GpioDataRegs.GPDTOGGLE.bit.GPIO97 = 1;

   GpioDataRegs.GPDTOGGLE.bit.GPIO97 = 1;

   fResult = __sqrt(fVal);

   GpioDataRegs.GPDTOGGLE.bit.GPIO97 = 1;

}

 

I want to measure the speed of the CLA with an oscilloscope at the GPIO97 pin.

 

After the program is downloaded and started on the launchpad I have measured the trace “C1” on the plot of the oscilloscope. After a “CPU reset” with the debugger and a new start of the program the runtime seems to be approximately three times shorter (see trace “M1”).

 

 

Why is the CLA after a new start three times faster?

 

 

Best regards

 

Ralf

  • Hello,
    I have found the problem!

    At the first time after downloading the program from the debugger to the DSP the software runs as intended from the RAM. After the first reset the DSP starts the program out of the flash, because the EMU_BOOT_MODE was set to FLASH. Unfortunately the old program in the flash has a quite similar waveform at the test pin. This was the reason for the confusion. After switching EMU_BOOT_MODE  to RAM the result was as expected.

    Best Regards

    Ralf

  • Ralf -

    Thank you for the follow-up.  I'm glad that you found the issue. 

    Regards

    Lori