Ups, just seen it (about sbi): "This instruction operates on the lower 32 I/O Registers – addresses 0-31."
Sorry for writing too early. Omar On Wed, Jan 4, 2012 at 9:06 PM, Omar Choudary <choudary.o...@gmail.com> wrote: > Hello, > > I wanted to use the _BV macro to set the JTD bit in MCUCR in order to > disable the JTAG interface and > allow the PF4-PF7 pins for other use. > > The listing result is this: > > MCUCR |= _BV(JTD); // needs to be done twice > 9cf2: 85 b7 in r24, 0x35 ; 53 > 9cf4: 80 68 ori r24, 0x80 ; 128 > 9cf6: 85 bf out 0x35, r24 ; 53 > MCUCR |= _BV(JTD); > 9cf8: 85 b7 in r24, 0x35 ; 53 > 9cfa: 80 68 ori r24, 0x80 ; 128 > 9cfc: 85 bf out 0x35, r24 ; 53 > > As you can see the instruction is xoring a temporary value instead of > using the expected sbi. > > On the other hand if I use the same approach for a normal port > register I get the desired result: > DDRF |= _BV(PF4); > 2d66: 84 9a sbi 0x10, 4 ; 16 > PORTF |= _BV(PF4); > 2d68: 8c 9a sbi 0x11, 4 ; 17 > > > Any ideas why _BV works for a port register but not for MCUCR? > I'm using AT90USB1287, avr-gcc 4.5.2. > > Thanks, > Omar _______________________________________________ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org https://lists.nongnu.org/mailman/listinfo/avr-gcc-list
