I know that the sqrt() function doesn't return an int value, but for me
it's ok, I tried to use this function and I accept this kind of
approximation with the truncation of the value, I'm working with integer
for the FFT.
Ing. Alessandro Balvis
Centro Ricerche ENEL - Pisa
[EMAIL PROTECTED]
> any idea what sqrt() function you are linking to?
> I doubt that a 'normal' root func would return an int.
> MS
>
>
> [EMAIL PROTECTED] wrote:
>> I dont' have problem with the packet maximum size, everything works ok
>> in
>> this way.
>> The problem is still with the int32_t data types:
>>
>>
>> ...
>> int32_t a,b,c;
>> for (i=0,m=0;i<NSIGNAL;i+=2,m++) {
>> a=((dat[i]/10)*(dat[i]/10));
>> b=((dat[i+1]/10)*(dat[i+1]/10));//ALL DATA UNTIL THIS POINT ARE
>> OK
>>
>> c=sqrt(a+b);
>> if((c == 128) && (m == 10)) call Leds.yellowOn();
>> ...
>>
>>
>>
>> I checked the data with the tinyviz, I reply the FFT algorithm to run
>> with
>> the simulator. Until the computation of "a" and "b" variables, I found
>> the
>> same values of the simulation (I used the check with the led).
>> After, when I calculate the "sqrt(a+b)", I don't found the same values,
>> something goes wrong.
>> Maybe there's some error? Thanks
>>
>>
>> Ing. Alessandro Balvis
>> Centro Ricerche ENEL - Pisa
>> [EMAIL PROTECTED]
>>
>>
>>
>>
>>>Remember that packet maximum size is 28 bytes.
>>>int32_t should not cause any problem .
>>>
>>>[EMAIL PROTECTED] wrote:
>>>
>>>
>>>>This is a good advice, I'll try this first check.
>>>>For the packet structure I have no problem, I'm developping a little
>>>>application for MDA300, and I can read the other datas that I put in
>>>> the
>>>>payload without problems, well the problem is not with the packet.
>>>>
>>>>It's possible that there's some problem with the management of data
>>>> type
>>>>int32_t? I can use this kind of data as well as the int16_t?
>>>>Thanks.
>>>>
>>>>
>>>>Ing. Alessandro Balvis
>>>>Centro Ricerche ENEL - Pisa
>>>>[EMAIL PROTECTED]
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>>Signor Balvis,
>>>>>una prima (grezza) controprova potrebbe essere quella di (se conosce
>>>>>quanto deve essere il valore
>>>>>corretto del risultato in anticipo) accendere dei led se il valore è
>>>>>quello giusto. Del tipo:
>>>>>
>>>>>if (zz.s[0] == <VALORE CORRETTO>) && (zz.s[1] == < VALORE CORRETTO >)
>>>>> &&
>>>>>.. )
>>>>> call Leds.redOn();
>>>>>
>>>>>Se il led si accende il risultato è corretto ma ci sono dei problemi
>>>>>nell'invio. In questo caso
>>>>>il problema è quasi sicuramente nel buffer di invio. Perchè accede a
>>>>>partire dalla posizione 10
>>>>>di data ? Provi da 0.
>>>>>Inoltre ha allocato un messaggio di tipo Tos_Msg a cui poi farà
>>>>> puntare
>>>>>il puntatore
>>>>>radio_msg_ptr ?
>>>>>Si assicuri che tutto funzioni mettendo nel pacchetto quantità note e
>>>>>vedendo se vengono
>>>>>visualizzate correttamente.
>>>>>
>>>>>Cordiali saluti
>>>>>Andrea
>>>>>
>>>>>
>>>>>
>>>>>[EMAIL PROTECTED] wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>Hy,
>>>>>>I've implemented an algorithm of integer FFT for micaz, but I've some
>>>>>>problems:
>>>>>>
>>>>>>1) I tested the FFT with TOSSIM for check the correct result and it
>>>>>>works
>>>>>>
>>>>>>2) I tested the FFT on micaz, but I can't read the result of the
>>>>>>computation, because I put the result in a int32_t variable and when
>>>>>> I
>>>>>>go
>>>>>>to write this variable in the packet (to read the packet with
>>>>>>MessageCenter java) it writes "zero". I thought that the problem was
>>>>>> in
>>>>>>the different data types: the value in the packet must be int16_t,
>>>>>> the
>>>>>>result is in int32_t. Then I used a type union:
>>>>>>
>>>>>>typedef union {
>>>>>> int8_t s[4];
>>>>>> int32_t i;
>>>>>> } UDATA;
>>>>>>
>>>>>>UDATA z;
>>>>>>
>>>>>>
>>>>>>In this way I can put the result in:
>>>>>>
>>>>>>z.i=(int32_t)result;
>>>>>>
>>>>>>and when I go to write the result in the packet I use the union:
>>>>>>
>>>>>>radio_msg_ptr->data[10] = zz.s[0];
>>>>>>radio_msg_ptr->data[10+2] = zz.s[1];
>>>>>>radio_msg_ptr->data[10+4] = zz.s[2];
>>>>>>radio_msg_ptr->data[10+6] = zz.s[3];
>>>>>>
>>>>>>But it still doesn't work. Why??
>>>>>>Can anybody help me? Thanks in advance.
>>>>>>
>>>>>>PS: I put the code of the FFT computation
>>>>>>
>>>>>>
>>>>>>int16_t FFT(int16_t kk[], int16_t fr[], int16_t isign, int16_t *Ampl,
>>>>>>int16_t *Freq) {
>>>>>>
>>>>>>
>>>>>> //variables for trigonometric recurrences
>>>>>> int32_t a,b,c,d,i,m;
>>>>>> int16_t idx,max,rms;
>>>>>> a = b = c = 0;
>>>>>>
>>>>>> call Leds.yellowOn();
>>>>>> BinaryInversion(datas);
>>>>>> Danielson(datas,isign);
>>>>>> max = 0; idx = 0;
>>>>>> rms = 1414L;
>>>>>> for (i=0,m=0;i<NSIGNAL;i+=2,m++) {
>>>>>> a=(int32_t)(kk[i]*kk[i]);
>>>>>> b=(int32_t)(kk[i+1]*kk[i+1]);
>>>>>> c = sqrt(c);
>>>>>> c=(a+b);
>>>>>> c=sqrt(c);
>>>>>> d=((c*100)/NSIGNAL)/100;
>>>>>> fr[m]=(d*rms)/1000;
>>>>>> if(fr[m]>max) {
>>>>>> max=fr[m];
>>>>>> z.i=fr[m];
>>>>>> idx=m;
>>>>>> }
>>>>>> }
>>>>>>
>>>>>> *Ampl = max; //memorizzati il valore di picco e la
>>>>>>componente relativa li memorizzo nel pacchetto
>>>>>> *Freq = idx;
>>>>>> call Leds.yellowOff();
>>>>>> post send_radio_msg();
>>>>>> return(0);
>>>>>> }
>>>>>>
>>>>>>
>>>>>>Ing. Alessandro Balvis
>>>>>>Centro Ricerche ENEL - Pisa
>>>>>>[EMAIL PROTECTED]
>>>>>>
>>>>>>_______________________________________________
>>>>>>Tinyos-help mailing list
>>>>>>[email protected]
>>>>>>https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>
>>
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