> Em 30/5/2011 17:51, IV3YNB op. Matteo escreveu:
>> Hi all !!!
>>
>> I'm an hobbyst and I am struggling to find the right example or the
>> right
>> application note to read, useful to solve my trouble:
>>
>> I have to control a DDS chip and I need to set his frequency: I have to
>> split a
>> 32 bits word into 4 bytes to manage the frequency into the DDS chip and
>> to save
>> in the memory of the PIC (I will use a 16F877 or similar).
>>
>>
>> May somebody help me? I am not asking for the exact assy code; I am
>> asking for
>> the right document to read and understand.
>>
>> Thank you in advance for your help
>> Matteo - IV3YNB
>>
>>
>>  Matteo Copetti -- IV3YNB -- JN65vp
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> http://www.iv3ynb.altervista.org
>> http://iv3ynb.splinder.it
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
>
> Example in C:
>
> long var;
> char byte0, byte1, byte2, byte3;
> ...
> var    =3D VALUE;
> byte0 =3D (char)var;
> byte1 =3D (char)(var >> 8 );
> byte2 =3D (char)(var >> 16 );
> byte3 =3D (char)(var >> 24 );
>
>
>

The way I like to do it in C (and I like types to tell me how many bits
there are, so I use stuff like uint8_t), is like this:

union{
 uint8_t byte[4];
 unint32_t long;
}value;
value.long=3D something.
most significant byte =3D value.byte[3];
least significant byte =3D value.byte[0];
since PIC is little endian.

Harold



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