a02426948b
This doesn't completely work for some reason as the first character of .data is corrupted, but otherwise it works.
61 строка
1,3 КиБ
ArmAsm
61 строка
1,3 КиБ
ArmAsm
.section .isr
|
|
isr:
|
|
rjmp reset
|
|
|
|
.org 0x18 ; WDT
|
|
rjmp wdt
|
|
|
|
; Startup code
|
|
.section .reset
|
|
.org 26
|
|
reset:
|
|
clr r1 ; r1 is expected to be 0 by the C calling convention
|
|
|
|
; Set up the stack pointer.
|
|
ldi xl, lo8(_stack_top)
|
|
ldi xh, hi8(_stack_top)
|
|
out 0x3d, xl; SPL
|
|
out 0x3e, xh; SPH
|
|
|
|
; Initialize .data
|
|
init_data:
|
|
ldi xl, lo8(_sdata)
|
|
ldi xh, hi8(_sdata)
|
|
ldi yl, lo8(_edata)
|
|
ldi yh, hi8(_edata)
|
|
ldi zl, lo8(_sidata)
|
|
ldi zh, hi8(_sidata)
|
|
init_data_loop:
|
|
cp xl, yl ; if x == y
|
|
cpc xh, yh
|
|
breq init_data_end ; goto main
|
|
lpm r0, Z+ ; r0 = *(z++)
|
|
st X+, r0 ; *(x++) = r0
|
|
rjmp init_data_loop ; goto init_data_loop
|
|
init_data_end:
|
|
|
|
; main will be placed right after here by the linker script so there's no
|
|
; need to jump.
|
|
|
|
|
|
; The only thing this WDT handler really does is disable itself, to get out of
|
|
; sleep mode.
|
|
.section .text.wdt
|
|
wdt:
|
|
push r16
|
|
|
|
clr r16
|
|
wdr ; Reset watchdog
|
|
out 0x34, r16 ; Clear reset reason (MCUSR)
|
|
|
|
; part 1: set WDCE and WDE to enable editing WDTCSR
|
|
lds r16, 0x60 ; r16 = WDTCSR
|
|
ori r16, 0x18 ; r16 |= WDCE | WDE
|
|
sts 0x60, r16 ; WDTCSR = r16
|
|
|
|
; part 2: within 4 clock cycles, set the new value for WDTCSR
|
|
clr r16
|
|
sts 0x60, r16 ; WDTCSR = 0
|
|
|
|
pop r16
|
|
reti
|