C2000 F28335 writing bits

Anthony Scarnici

Expert 1155 points

Hey all,

If I have a 16 bit variable called "zone" and I need to read bit 15 or write bit 3 how do I go about that ?

thanks

over 13 years ago

0 Vivek Sankaranarayanan98982 over 13 years ago

Expert 2115 points

Assuming lsb starts from bit 0 and msb is bit 15.

#define BIT0 0x0001

#define BIT15 0x8000

// reading bit 16

if ((zone & BIT15) == BIT15) // Check whether bit15 is 1

{

Statement 1;

}

else // Bit 15 is 0

{

Statement 0;

}

// Write 1 to bit 3

zone |= BIT3;

// Write 0 to Bit 3

zone &= ~(BIT3);

0 Devin Cottier over 13 years ago

TI__Guru 60865 points

You can also implement bit fields as is done in the heade files. This structure is described here: http://www.ti.com/lit/an/spraa85c/spraa85c.pdf .this has alot of upfront cost organizing everything, but the compiler will take care of the mechanics of the reads and writes (by doing some bit manipulations, similar to above).

0 Anthony Scarnici over 13 years ago in reply to Vivek Sankaranarayanan98982

Expert 1155 points

Thanks Vivek,

I was hoping to avoid having to set up a whole structure just to handle it, and it lks like you may have helped me. My interst was to read the sign bits of 3 variables and set or clears bits 0:3 of another variable accordingly. I'm attempting to save cycle time by avoiding shifts if possible, which is why I asked .

David thanks for your assistance, Hopefully I won't need a struct!

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