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Unable to extract 8 bit data from 16-bit variable in the CCS compiler

Kamal Sandeep
Prodigy 100 points


Hi...

I am using TSM320f28035 controller for one of my application.

I am using a structure for my variables and want to extract 8-bit data from it in different register in a optimized way.

I have declared the variable as follows.

typedef struct DATA
{
      Uint16 A1;
      Uint16 A2;
      Uint16 A3;
      
}Parameters;

 

 typedef union  DATA

   {

          Parameters B1;

          Uint16 ARRAY16[ 3];

          Uint8   ARRAY8[6];  

   }extract;

When compiled and try to extract data from the ARRAY16, the data of the element of the structure reflects in the buffer.

But I get some garbage value in the ARRAY8. 

Will you please suggest what should I do to get the 8-bit data in the register in a optimized way?

Regards,

Kamal

  • 0
    TI__Guru 54175 points

    I'm not sure where the Uint8 you're using is defined, but you can't have a Uint8 on the C28 that is truly 8 bits. Check out the "Data Types" section of the compiler user guide and note that a char is 16 bits.

    To access data 8-bits at a time you can define a structure with 8-bit bit-fields, use the __byte() intrinsic on a Uint16, or do the somewhat more manual work of masking and shifting out the 8 bits you're interested in in a Uint16.

    Whitney