AVR-Chat

The SBI instruction only modifies one bit (0-7) at a time.  You are trying
to modify a whole byte.

The compiler probably generates a IN, ORI , OUT instruction sequence.  One
of the weird things about AVR is that I/O access is bit oriented (since
often you only want to play with one bit of a register) while the register
bit manipulation is byte wide.  In fact, there are no CBR/SBR instructions,
they are assembler aliases for ANDI and ORI...  I am not sure why Atmel put
those there since they are very confusion when put along side the SBI/CBI
instructions.

You could save one word by doing two SBI's...

Cheers!
-----Original Message-----
From: jay marante

i have this code with ICCAVR:

TCCR1A |= (1<<COM1A1)|(1<<COM1A0);

i wanted to replace that code with this assembly code:

asm("SBI TCCR1A,COM1A1+COM1A0\n");

because i found out that the assembly code that the compiler generate has
three sets of instructions. i think that if i replace the C code with the
corresponding assembly code, i might optimize the flash memory.

but i get this error when i compile it:

"absolute expression expected"

what's wring with my code? did i get it right?
thanks for the help.