An Example: Blink

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Code

  .include "m328Pdef.inc"

  .def    mask    = r16
  .def    ledR    = r17
  .def    oLoopR  = r18
  .def    iLoopRl = r24
  .def    iLoopRh = r25

  .equ    oVal    = 71
  .equ    iVal    = 28168

  .cseg
  .org    0x00

  ; set PINB5 to output
  clr   ledR
  ldi   mask, (1<<PINB5)
  out   DDRB, mask

start:
  eor   ledR, mask ; toggle PINB0 in ledRegister
  out   PORTB, ledR ; write LedRegister to PortB

  ldi   oLoopR, oVal ; initialize outer Loop count

oLoop:
  ldi   iLoopRl, LOW(iVal)
  ldi   iLoopRh, HIGH(iVal) ; initialize inner Loop count
  ; LOW and HIGH give us lower and upper part of the value
  ; Done by assembler, not hardware

iLoop:
  sbiw    iLoopRl, 1
  brne    iLoop

  dec   oLoopR
  brne  oLoop

  rjmp    start

Code Analyze

::.def

We can use .def directive to give registers names that we can remember easly.

.def    mask = r16
; alias for r16 with 'mask'

::.equ

Like .def directive we can use .equ for give names to constant values.

.equ    oVal = 71
; alias for 71 with oVal

Detailed Analyze

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