Moin Moin,
Ich habe mir für mein Entwicklerboard einen Testcode gedownloadet. es
sieht so aus:
1 | /* Sample program for Olimex AVR-P28 with ATMega8 processor
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2 | * Blinks the led with a speed ~2Hz using a simple delay loop.
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3 | * Compile with AVRStudio+WinAVR (gcc version 3.4.6)
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4 | */
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5 |
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6 | #define __AVR_ATmega8__ 1
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7 |
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8 | #include "avr/io.h"
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9 |
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10 | void Initialize(void)
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11 | {
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12 | PORTB = 0x0;
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13 | PORTC = 1<<5; /* turn the LED off */
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14 | PORTD = 0x0;
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15 |
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16 | DDRB = 0x0;
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17 | DDRC = 1<<5; /* PC5 as output - the LED is there */
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18 | DDRD = 0x0;
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19 |
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20 | }
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21 |
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22 | /* state = 0 -> Led Off
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23 | * state = 1 -> Led On
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24 | * state !=[0,1] -> Led Toggle
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25 | */
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26 | void LedSet(unsigned char state)
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27 | {
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28 | switch (state)
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29 | {
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30 | case 0:
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31 | PORTC = 0xff;
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32 | break;
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33 | case 1:
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34 | PORTC = 0x00;
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35 | break;
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36 | default:
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37 | if (PORTC = 0xff)
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38 | PORTC = 0x00;
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39 | else
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40 | PORTC = 0xff;
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41 | }
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42 |
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43 | }
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44 |
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45 |
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46 | int main(void)
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47 | {
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48 | int i;
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49 |
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50 | Initialize();
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51 |
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52 | while (1)
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53 | {
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54 | LedSet(1);
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55 | for (i=60000;i;i--);
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56 | LedSet(0);
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57 | for (i=60000;i;i--);
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58 | }
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59 | return 0;
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60 | }
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Effekt: meine LED auf dem Board blinkt. Ich verstehe ja auch warum die
blinkt.
Was ich aber nicht verstehe... Wenn ich den Code wie folgt umänder,
müsste sie, nach meinem verständnis dauerhaft leuchten. tut sie aber
nicht. Um ehrlich zu sein macht die LED dann garnichts mehr.
(Geändert habe ich beim unteren LedSet die 1 in eine 0)
1 | /* Sample program for Olimex AVR-P28 with ATMega8 processor
|
2 | * Blinks the led with a speed ~2Hz using a simple delay loop.
|
3 | * Compile with AVRStudio+WinAVR (gcc version 3.4.6)
|
4 | */
|
5 |
|
6 | #define __AVR_ATmega8__ 1
|
7 |
|
8 | #include "avr/io.h"
|
9 |
|
10 | void Initialize(void)
|
11 | {
|
12 | PORTB = 0x0;
|
13 | PORTC = 1<<5; /* turn the LED off */
|
14 | PORTD = 0x0;
|
15 |
|
16 | DDRB = 0x0;
|
17 | DDRC = 1<<5; /* PC5 as output - the LED is there */
|
18 | DDRD = 0x0;
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19 |
|
20 | }
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21 |
|
22 | /* state = 0 -> Led Off
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23 | * state = 1 -> Led On
|
24 | * state !=[0,1] -> Led Toggle
|
25 | */
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26 | void LedSet(unsigned char state)
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27 | {
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28 | switch (state)
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29 | {
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30 | case 0:
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31 | PORTC = 0xff;
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32 | break;
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33 | case 1:
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34 | PORTC = 0x00;
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35 | break;
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36 | default:
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37 | if (PORTC = 0xff)
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38 | PORTC = 0x00;
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39 | else
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40 | PORTC = 0xff;
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41 | }
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42 |
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43 | }
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44 |
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45 |
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46 | int main(void)
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47 | {
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48 | int i;
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49 |
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50 | Initialize();
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51 |
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52 | while (1)
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53 | {
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54 | LedSet(0);
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55 | for (i=60000;i;i--);
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56 | LedSet(0);
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57 | for (i=60000;i;i--);
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58 | }
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59 | return 0;
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60 | }
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Meine Frage ist nun: Wieso leuchtet die LED nicht mehr???
