Atmel AVR AT90S8515-4 Uživatelský manuál stáhnout pdf (Strana 11)

AN INTRODUCTION INTENDED FOR PEOPLE WITH NO PRIOR AVR KNOWLEDGE - AVRFREAKS.NET

In the output view (at the bottom left of the screen) you should get the following

output indicating that the Project compiled correctly without any errors! From this

output window, we can also see that our program consists of 6 words of code (12

bytes).

Congratulations!! You have now successfully written your first AVR program,

and we will now take a closer look at what it does!

Note: If your program does not compile, check your assembly file for typing

errors.If you have placed the include files (8515def.inc) in a different folder than

the default, you may have to enter the complete path to the file in the .include

"c:\complete path\8515def.inc" statement.

When it compiles we will continue explaining and then debugging the code.

Understanding the Source Code

OK so the code compiled without errors. That's great, but let us take a moment to

see what this program does, and maybe get a feeling how we should simulate the

code to verify that it actually performs the way we intended. This is the complete

source code:

Sample Code

;My Very First AVR Project

.include "8515def.inc" ;Includes the 8515 definitions file

.def Temp = R16 ;Gives "Defines" Register R16 the name Temp

.org 0x0000 ;Places the following code from address 0x0000

rjmp RESET ;Take a Relative Jump to the RESET Label

RESET: ;Reset Label

ldi Temp, 0xFF ;Store 255 in R16 (Since we have defined R16 = Temp)

out DDRB, Temp ;Store this value in The PORTB Data direction Register

Loop: ;Loop Label

out PORTB, Temp ;Write all highs (255 decimal) to PORTB

dec Temp ;Decrement R16 (Temp)

rjmp Loop ;Take a relative jump to the Loop label

Now let's take a line-by-line look at what's going on in this code.

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 17

Žádné komentáře

Atmel AVR AT90S8515-4 Uživatelský manuál Strana 11