Ich probiere mich gerade an einem Interrupt-Timer, allerdings hänge ich
bei der genauen Berechnung der Zeit fest. Dabei ist das größte Problem
eigentlich, dass ich nicht weiß mit welcher Frequenz der interne
Oszillator vom Atmega16 läuft.
Im Gegensatz zu dem Beispiel aus dem Wiki
(https://www.mikrocontroller.net/articles/AVR_Fuses#AVRDUDE) zeigt
avrdude nämlich keine Oszillator Frequenz:
1 | avrdude -p m16 -c avrisp2 -P usb -n -v
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2 |
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3 | avrdude: Version 6.2, compiled on Dec 16 2015 at 07:10:46
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4 | Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/
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5 | Copyright (c) 2007-2014 Joerg Wunsch
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6 |
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7 | System wide configuration file is "/usr/local/Cellar/avrdude/6.2/etc/avrdude.conf"
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8 | User configuration file is "/Users/bodokaiser/.avrduderc"
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9 | User configuration file does not exist or is not a regular file, skipping
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10 |
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11 | Using Port : usb
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12 | Using Programmer : avrisp2
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13 | avrdude: usbdev_open(): Found AVRISP mkII, serno: 000200220428
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14 | AVR Part : ATmega16
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15 | Chip Erase delay : 9000 us
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16 | PAGEL : PD7
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17 | BS2 : PA0
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18 | RESET disposition : dedicated
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19 | RETRY pulse : SCK
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20 | serial program mode : yes
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21 | parallel program mode : yes
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22 | Timeout : 200
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23 | StabDelay : 100
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24 | CmdexeDelay : 25
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25 | SyncLoops : 32
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26 | ByteDelay : 0
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27 | PollIndex : 3
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28 | PollValue : 0x53
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29 | Memory Detail :
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30 |
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31 | Block Poll Page Polled
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32 | Memory Type Mode Delay Size Indx Paged Size Size #Pages MinW MaxW ReadBack
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33 | ----------- ---- ----- ----- ---- ------ ------ ---- ------ ----- ----- ---------
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34 | eeprom 4 10 128 0 no 512 4 0 9000 9000 0xff 0xff
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35 | flash 33 6 128 0 yes 16384 128 128 4500 4500 0xff 0xff
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36 | lock 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
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37 | lfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
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38 | hfuse 0 0 0 0 no 1 0 0 9000 9000 0x00 0x00
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39 | signature 0 0 0 0 no 3 0 0 0 0 0x00 0x00
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40 | calibration 0 0 0 0 no 4 0 0 0 0 0x00 0x00
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41 |
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42 | Programmer Type : STK500V2
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43 | Description : Atmel AVR ISP mkII
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44 | Programmer Model: AVRISP mkII
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45 | Hardware Version: 1
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46 | Firmware Version Master : 1.23
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47 | Vtarget : 2.4 V
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48 | SCK period : 8.00 us
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49 |
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50 | avrdude: AVR device initialized and ready to accept instructions
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51 |
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52 | Reading | ################################################## | 100% 0.00s
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53 |
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54 | avrdude: Device signature = 0x1e9403 (probably m16)
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55 | avrdude: safemode: hfuse reads as 99
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56 |
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57 | avrdude: safemode: hfuse reads as 99
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58 | avrdude: safemode: Fuses OK (E:FF, H:99, L:E1)
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59 |
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60 | avrdude done. Thank you.
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Mein aktuelles Programm sieht so aus:
1 | #include <avr/io.h>
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2 | #include <avr/interrupt.h>
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3 |
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4 | volatile int count = 0;
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5 |
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6 | int main(void) {
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7 | DDRA = (1 << PA0);
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8 | DDRB = (1 << PB0);
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9 | DDRD = (1 << PD0);
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10 |
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11 | PORTA &= (1 << PA0);
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12 | PORTB |= (1 << PB0);
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13 | PORTD ^= (1 << PD0);
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14 |
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15 | TIMSK = (1 << TOIE0);
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16 | TCCR0 = (1 << CS02) | (1 << CS00);
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17 | TCNT0 = 0x00;
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18 |
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19 | sei();
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20 |
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21 | for (;;) {
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22 | if (count < 10) {
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23 | PORTD ^= (1 << PD0);
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24 | }
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25 | };
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26 |
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27 | return 0;
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28 | }
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29 |
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30 | ISR (TIMER0_OVF_vect) {
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31 | count++;
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32 | }
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Dabei schaltet sich die LED nach ca. 3s aus. Daraus die Frequenz
herzuleiten führt irgendwie auch nicht ganz zum richtigen Ergebnis
(glaub ich, Prescaler p, Counts c, Frequenz f, Zeit t):
