Code execution speed in TMS320F28335

Hi Sandesh

Are you sure, your code is running from RAM now? Did you mark your time critical code with the pragma

#pragma

Depending on your code size it will be difficult or even impossible to run it entirely from RAM, you need to copy the critical sections and run the rest from FLASH

Best regards,

Andreas

That's one of the reasons I went to the 28346, everything runs from RAM.

John

Yes Andreas,

I have done that.

#pragma CODE_SECTION(adcTick, "ramfuncs");
#pragma CODE_SECTION(cpu_timer0_isr, "ramfuncs");
#pragma CODE_SECTION(epwm1_isr, "ramfuncs");
#pragma CODE_SECTION(spiTxFifoIsr, "ramfuncs");

But still wonder why my function adcTick is not as fast as running form RAM.

Regards

Sandesh

Hi Tim,

I tried to implement your application note and got multiple error. One problem was once as implemented "copy_sections" , i am confused where to put

LB _c_int00 ; Branch to start of boot.asm in RTS library

Also in DSP28xx_SectionCopy_nonBIOS.asm has extra line of SUBB ACC,#1 , which has not been speciifed in your app note.

And few more errors. Is there any specific example to do this for TMS320F28335 as your application demonstrates using TMS320F2808.

Also do you have any idea why my function, which as been specified to run form RAM, is not as fast as running entire things from RAM. My function does not uses any lib function nor has any fucntions call.

Regards

Sandesh

Hi Sandeesh

I can think of three issues that you might be having:

1. You forgot to edit the linker file to specify different load and run addresses. So while you do copy the function from FLASH to RAM, it is the function in the Flash that gwets called. You can easily check this by observing th PC (program counter) when you enter the function.

or

2. Within the function you have multiple accesses to constants/data placed in FLASH

or

3. the function is in the same memory block as the date the function is working on so you get multiple pipeline stalls

Regards, Mitja

Hi Mitja,

Thanks for the response.

I can definitely rule out possibility 1 because my code does get faster ( only problem is, it is not as fast as running whole setup entirely from ram). Had it been running form Flash i would not have seen speed improvement. My program Counter before main is 0x33C000. and before ram fucntion is 0x33C71D. I am not sure what that means.

Regarding 2 and 3, all my varialbes are located in @data sections. My code and data memory ( so far as i know from CMD file) is located in different RAM section.

I checked by expanding my variable size equal to allowed RAM size and it compiled fine.

Regards

Sandesh

Hi Sandesh

check the program counter when you enter the function and not before you enter the function. It should be in some RAM block. If I remember correctly some of the RAM blocks in 28335 have wait-states (check memory maps in SPRS439)

Regarding the code and data placement be aware that you can still put two different sections (e.g. .ebss and .text) in the same memory block (L0SARAM), so check precisely in which memory block each section goes (maybe you did, but I can not tell from your answer as you must be very specific if you are talking about memory section or blocks)

Regards, Mitja

Hi Mitja,

I think you are right. I am just a beginner at C2000 but here is my obervation. 

My Program counter has address 0x33C91C when in this function.

e.g. 0x33C924:   0622        MOVL       ACC,@34 ( when viewed in disassembly)

Now my F28334.cmd commnds says that...

 FLASHA      : origin = 0x33C000, length = 0x003F80     /* on-chip FLASH */

This actually contains my PC, which is 0x33C924.

Does that mean my code is still running form Flash. If yes, can you please tell why,

I use, #pragma CODE_SECTION(sampleData, "ramfuncs");  for running it in RAM 

i declare

extern Uint16 RamfuncsLoadStart;
extern Uint16 RamfuncsLoadEnd;
extern Uint16 RamfuncsRunStart;

and call

   MemCopy(&RamfuncsLoadStart, &RamfuncsLoadEnd, &RamfuncsRunStart);

// Call Flash Initialization to setup flash waitstates
// This function must reside in RAM
   InitFlash();

in main code. I folow all steps specified in DSP2833x_HeaderFiles_QuickStart_Readme.pdf file.....

Regards

Sandesh

Mitja,

I did go through all the steps as instructed in "DSP2833x_HeaderFiles_QuickStart_Readme.pdf".

- I first linked F28334.cmd

- included password.asm file.

- added files to be executed from RAM by

#pragma CODE_SECTION(sampleData, "ramfuncs");
#pragma CODE_SECTION(adcTick, "ramfuncs");
#pragma CODE_SECTION(cpu_timer0_isr, "ramfuncs");
#pragma CODE_SECTION(epwm1_isr, "ramfuncs");
#pragma CODE_SECTION(spiTxFifoIsr, "ramfuncs");

- then i checked SECTION code in my CMD file and it is what the pdf file says...

   /* Allocate program areas: */
   .cinit              : > FLASHA      PAGE = 0
   .pinit              : > FLASHA,     PAGE = 0
   .text               : > FLASHA      PAGE = 0
   codestart           : > BEGIN       PAGE = 0
   ramfuncs            : LOAD = FLASHD,
                         RUN = RAML0,
                         LOAD_START(_RamfuncsLoadStart),
                         LOAD_END(_RamfuncsLoadEnd),
                         RUN_START(_RamfuncsRunStart),
                         PAGE = 0

- included DSP2833x_MemCopy.c in project and added MemCopy(&RamfuncsLoadStart, &RamfuncsLoadEnd, &RamfuncsRunStart);

- define RAMfunctions varialbes....

- finally add

 MemCopy(&RamfuncsLoadStart, &RamfuncsLoadEnd, &RamfuncsRunStart); and

InitFlash(); in my main code...

Can you see anything wrong with this....

Thanks for your reply...

Regards

Sandesh

Hi Mitja,

Thank you so much for your presistent reply. I finally go to get it running from RAM and yes, it did improve my execution speed.

Problem; actually there was not any. I had all the #pragma CODE_SECTION(......., "ramfuncs"); directives put in main and that seems to be problem. Thanks to you, I checked the location of all these function that needed to run form ram and i was actually in flash.

So when i checked 0x008000 ( RAML0) it has only two function, which was InitFlash() and delay_us. I saw that, #pragma CODE_SECTION(InitFlash, "ramfuncs"); was declared in DSP2833x_SysCtrl.c and not it main. So I did the same. I put all the corresponding #pragma for my functions in same file as it was been defined in. And that worked....

This could be bug in CCS or my ignorance...

Regards

Sandesh