LAUNCHXL-F280025C: DCC counters

Hi Ushma,

Please use the calculations from section "6.2.1 Configuring DCC counters" section, one in the example needs to be updated. Recommendation is to use section "Configuring DCC counters" to calculate counter configuration.

Your calculation below is not correct, I have added my comments:

1. Procedure I followed is from page number 623 from Reference manual tms320f28002 and here are some calculations :

PLL frequency  100MHz  that is clock1

Clock0 10MHz

             Both (I am assuming Allowable Frequency tolerance is also 1%)  Tolerance is 1 %  then I have the following counter values

            DCC error : 30

           Window : 3000

          Frequency error allowed 30

          Total error 30+30=60 (DCC Error + Frequency Error allowed)

         Counter0 : 30(Window - Total Error = 3000 - 60 = 2940)

          Counter1:30000

          Valid0 : 2*3030 : 2*60 = 120

          In this case  : error detection time is around 600us and test time is 300us 

Total time for DCC to run and compute if there is any error will be same as Window*Clock0 time = 3000*100E-9 = 300us

We will get the Example values match the calculations defined in the section "6.2.1 Configuring DCC counters".

Best Regards,

Nirav

Hello Nirav, 

Correct me if I am wrong but in my understanding :

error detection time is  = countre0 goes to 0 + valid0 goes to 0 = 294+12 = 306 us 

Sorry but i dont get why it is 600us because we start decrementing both the ountres simultaneously Right ? 

Thanks 

Ushma 

Hello Nirav , 

Here we talked about two tolerances : 

1. Tolerance 

2. Allowable frequency tolerance 

I have this information and would like to ask which tolerance specify the tolerance mentioned in the below picture ?

Hello Nirav , 

I am using the following Code: 

to set the values but when in debug  mode i put the break Point and try to see the counters i can see wither false value or not at all  

Could you please help me why is it so ? 

just for the info i am Setting These values  :

#define VALID   240
#define COUNT0  2880
#define COUNT1  33000

It will be Allowable Frequency tolerance.

Best Regards,

Nirav

Sorry, I did not understand your question?

Counter will be still running even though you are in debug mode, because clock to both the counters are free running.

Best Regards,

Nirav

Hello Nirav , 

I meant seed values of the counter , as i am loading the seed values like the following 

DCCCNTSEED0  2880

DCCCNTSEED1 33000

DCCVALIDSEED0   240

So i expect to see the same in the Registers repectively .

But as you see in the Picture they are either not updated or falsely updated for example

DCCCNTSEED0 is 33000

DCCCNTSEED1 is not at all updated and DCCVALIDSEED0 is also false .My Question is why is it so ?

Code is attached above .

Thanks 

Ushma 

Hi Ushma,

Why are you adding +2 to the offset address inside the code "HWREGH(base + DCC_O_CNTSEED0 + 2U) "? Why dont you assign counter0seed and counter1seed value directly as you do with validcounter0 value " HWREGH(base + DCC_O_VALIDSEED0) = validCounter0;"

Also, are you using C2000Ware driverlib function? If not, I would highly recommend using that.

Best Regards,

Nirav

Hello Nirav, 

firstly, I tried the way you mentioned no Change in the result:

So, I am following excatly the Code from the C200Ware/ driverlib /f28002x/driverlib/ dcc.c from there DCC_continuousMonitor fucntion  , if this what you are saying to use then yes i am already doing that .

ALso i tried with this way using structure instead of using HWREGH : 

 DccRegs->DCCCNTSEED0.bit.COUNTSEED0 = counter0; // Loaded Counter0 Value
       DccRegs->DCCVALIDSEED0.bit.VALIDSEED = validCounter0;  // Loaded Valid Value
        DccRegs->DCCCNTSEED1.bit.COUNTSEED1 = counter1;

but same Problem. Could you guide me further ?

Thanks 

Ushma 

Hi Ushma,

That is strange, can you send me your code file? Your code-snippet looks fine, how does the counter0 value get assigned? Also can you also send structure of DCCREGS defined in your code. Some reason it looks like the offset is not mapped correctly.

Best Regards,

Nirav

Hello Nirav, 

i would liek to send it personally . Could you please accept the request so thta i can send personally?

Hi Ushma - I just accepted the request.

Best Regards,

Nirav