What does << mean?

[Mosaic]

MOVF      PORTB,W                  ; Read DQ
             ANDLW     1<<DQ                    ; Mask off the DQ bit

Can anyone explain the andlw 1<<DQ line function please?

 

[Pommie]

It means shift left and so, 1<<3 would be 1000 = 8 and 1<<7 = 10000000 = 128.

Mike.

 

[Mosaic]

ok thx.
so DQ must be a fixed number, not updatable within the code.

 

[blueroomelectronics]

Yep, it's done during assembly. If you want to shift a variable use the rotate instruction.

 

[bryan1]

ok thx.
so DQ must be a fixed number, not updatable within the code.

Mosaic, Read the comments on the code
; Read DQ (bit)
; mask off the DQ bit

so now do you think DQ is fixed ??????

I'll near bet this is Maxims one wire code

Cheers Bryan