If I have a symbol in my code like this:
motor_stepping:
.byte 0x08, 0x04, 0x02, 0x01
How do I tell the assembler that I want to stick its address into X? I can't find an opcode to do this and there seems to be no documentation whatsoever on avr-as. Thanks.
How do I tell the assembler that I want to stick its address into X?
ldi r26, lo8(motor_stepping) ldi r27, hi8(motor_stepping)
You could also create a macro:
.macro ldx _var ldi r26, lo8(\_var) ldi r27, hi8(\_var) .endm
Then, it could be used thusly:
ldx motor_stepping
Thanks, it works! Where is this documented? I'd love to RTFM but I can't find it :(
Where is this documented?
Actually, it doesn't work.
This is what the assembler puts out:
B0E0 LDI R27, hi8(motor_stepping)
A0E0 LDI R26, lo8(motor_stepping)
If I'm not mistaken, those opcodes store zeroes and my label is not at zero.
I'm trying to put the value stored there out on PORTB. Is this correct?
LD R17, X
OUT PORTB, R17
Thanks again.
OK, here's my updated and still broken code:
move_motor: LDI R31, hi8(motor_stepping) LDI R30, lo8(motor_stepping) INC R30 LD R19, Z OUT PORTB, R19 RET motor_stepping: .byte 0x40, 0x40, 0x20, 0x10 check_tach: RET
What I want it to do is fetch 0x40 from the table and put it on PORTB. I noticed that in the binary code, the assembler claims it's writing 0xE0E0, but in reality, 0x02E1 is in its place. Is the linker doing this? I put the INC R30 there as a debugging measure. Presumably, if R30 is being written in the line above with a constant value, R30 should end up being that value +1, but instead, I get constantly changing values on PORTB, as if nothing was being written to R30 at all.
On another note, are there any decent assemblers for linux that use Atmel's syntax? I downloaded tavrasm, but it doesn't support the new generation of AVRs. I also tried avra, but it doesn't produce binaries.
What I want it to do is fetch 0x40 from the table and put it on PORTB.
I tried LD, LPM, LDS and the result is still the same.
LDI R31, hi8(pm(motor_stepping))
LDI R30, lo8(pm(motor_stepping))
doesn't work.
LDI R31, hi8(motor_stepping)
LDI R30, lo8(motor_stepping)
doesn't either.
What I was saying in my other post is that these two lines do not seem to move ANY value into R30 or R31, because when I increment R30 and put it on the port, it's a constantly increasing value. These two LDI commands seem to do nothing.
> If I'm not mistaken, those opcodes store zeroes and
> my label is not at zero.
Wait: let me guess... you've only feeding us pieces of a large
puzzle, but my crystal ball just tells me that you were trying
to use the relocatable object file, rather than passing it through
the linker.
