I ran into problems with a simple led flashing program written in assembly; after a dozen or so tries of flashing slightly different versions of the code, I started looking at the generated code and realized avr-gcc was not putting in proper branch and jump offsets. I'm running 32-bit OpenSuse, and was initially using the cross-avr-gcc package (which includes avr-gcc-433). I uninstalled that and installed an rpm of avr-gcc-453; still no go. And avr-gcc 47.
Next I tried DigisparkArduino-Linux32-1.0.4-May19 (which includes an old avr-gcc-4.3.2). As expected, no go.
Here's the assembly code:
/* needed for <avr/io.h> to give io constant addresses */
#define __SFR_OFFSET 0
/* AVR CPU definitions based on -mmcu flag */
#include <avr/io.h>
.text
.org 0x0000
sbi DDRB, DDB0 ; set BP0 to output
ldi r16, 0xff
sbi PORTB, PORTB0 ; turn on LED
Delay1:
adiw XL, 1
brne Delay1
cbi PORTB, PORTB0 ; turn off LED
Delay2:
adiw XL, 1
brne Delay2
inc r0
brne Delay2
sbi PORTB, PORTB0 ; turn on LED
rjmp Delay1
rjmp Delay2 ; just to check compiler output
; sbi PINB, PINB0 ; toggle pin
Here's a snippet of the dissassembled output (avr-objdump -D)
I'm compiling with -mmcu=attiny85 -x assembler-with-cpp
00000006 <Delay1>:
6: 11 96 adiw r26, 0x01 ; 1
8: 01 f4 brne .+0 ; 0xa <Delay1+0x4>
a: c0 98 cbi 0x18, 0 ; 24
0000000c <Delay2>:
c: 11 96 adiw r26, 0x01 ; 1
e: 01 f4 brne .+0 ; 0x10 <Delay2+0x4>
10: 03 94 inc r0
12: 01 f4 brne .+0 ; 0x14 <Delay2+0x8>
14: c0 9a sbi 0x18, 0 ; 24
16: 00 c0 rjmp .+0 ; 0x18 <Delay2+0xc>
18: 00 c0 rjmp .+0 ; 0x1a <Delay2+0xe>
The brne instructions all generate 01 f4, (offset 0), and the rjmp offsets are both zero as well (actually absolute address 0 since the 12-bit "offset" covers the full 8K (4K word) address space on the tiny85).
Any ideas on how I get a working avr-gcc?
