Load_Program_Memory_to_Port_AVR108_appnote

диагностика частотного преобразователя

                              ;**** A P P L I C A T I O N   N O T E   A V R 1 0 8 ************************
                              ;*
                              ;* Title:  Load Program Memory
                              ;* Version:  1.0
                              ;* Last updated: 98.12.17
                              ;* Target:  AT90Sxx1x and higher (Devices with SRAM)
                              ;*
                              ;* Support E-mail: avr@atmel.com
                              ;*
                              ;* DESCRIPTION
                              ;* This Application note shows how to use the Load Program Memory (LPM)
                              ;* instruction. The App. note loads the string "Hello World" from 
                              ;* program memory byte by byte, and puts it onto port B.
                              ;*
                              ;***************************************************************************

.include "8515def.inc"
.device AT90S8515             ; Specify device

.def temp=r16                 ; Define temporary variable

start: 
       ldi temp,low(RAMEND)
       out SPL,temp           ; Set stack pointer to last internal RAM location
       ldi temp,high(RAMEND)
       out SPH,temp

       ldi temp,$ff
       out PORTB,temp         ; Set all pins at port B high
       out DDRB,temp          ; Set port B as output
                              ; Load the address of 'message' into the Z register. Multiplies
                              ; word address with 2 to achieve the byte address, and uses the
                              ; functions high() and low() to calculate high and low address byte.



       ldi ZH,high(2*message) ; Load high part of byte address into ZH
       ldi ZL,low(2*message)  ; Load low part of byte address into ZL

loadbyte:
       lpm                    ; Load byte from program memory into r0
       tst r0                 ; Check if we've reached the end of the message
       breq quit              ; If so, quit
       out PORTB,r0           ; Put the character onto Port B
       rcall one_sec_delay    ; A short delay
       adiw ZL,1              ; Increase Z registers
       rjmp loadbyte

quit:
       rjmp quit

one_sec_delay:
       ldi r20, 20
       ldi r21, 255
       ldi r22, 255

delay: 
       dec r22
       brne delay
       dec r21
       brne delay
       dec r20
       brne delay
       ret

message:
       .db "Hello World"
       .db 0