root / branches / rbom / code / projects / colonet / utilities / robot_wireless_relay / buzzer.c @ 1390
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1 | 13 | emarinel | /*
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2 | buzzer.c - Contains the functions necessary for running the buzzer
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3 | |||
4 | author: Robotics Club, Colony Project
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5 | |||
6 | much taken from FWR's firefly library (author: Tom Lauwers)
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7 | */
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8 | |||
9 | #include <avr/io.h> |
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10 | #include <buzzer.h> |
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11 | #include <time.h> |
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12 | |||
13 | /*
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14 | initializes buffer
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15 | this function must be called before the buzzer can be used
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16 | */
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17 | void buzzer_init( void ) |
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18 | { |
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19 | // Set pin D7 to output - D7 is buzzer pin
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20 | DDRB |= 0x80;
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21 | |||
22 | // Set to Fast PWM mode, toggle the OC0A pin (D6) on output compare
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23 | // matches, and select a clock prescalar of 64 for the counter.
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24 | // Counter FREQ = 8000000/64 = 125000
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25 | //01011000
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26 | TCCR2 = 0x1B;
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27 | OCR2=100;
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28 | } |
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29 | |||
30 | // Set the buzzer value - takes a value from 0-255
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31 | // Higher values are lower frequency. Take a look at
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32 | // the buzzer frequency table to see how a given value
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33 | // correlates to a frequency.
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34 | void buzzer_set_val(unsigned int buzz_value) |
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35 | { |
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36 | OCR2 = buzz_value; |
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37 | } |
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38 | |||
39 | // Set the buzzer frequency - takes any value and tries to find the nearest
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40 | // buzzer frequency
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41 | void buzzer_set_freq(unsigned int buzz_freq) |
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42 | { |
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43 | int buzz_value;
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44 | |||
45 | buzz_value = 62500/buzz_freq - 1; |
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47 | if(buzz_value > 255){ |
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48 | buzz_value = 255;
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49 | }else if(buzz_value < 0){ |
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50 | buzz_value = 0;
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51 | } |
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52 | |||
53 | buzzer_set_val(buzz_value); |
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54 | } |
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55 | |||
56 | // Chirps the buzzer for a number of milliseconds
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57 | void buzzer_chirp(unsigned int ms, unsigned int buzz_freq) |
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58 | { |
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59 | buzzer_set_freq(buzz_freq); |
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60 | delay_ms(ms); |
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61 | buzzer_off(); |
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62 | } |
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63 | |||
64 | // Disables timer0 clock counting, turning off the buzzer
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65 | void buzzer_off()
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66 | { |
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67 | // Disable clock, to halt counter
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68 | TCCR2 &= 0xF8;
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69 | |||
70 | // Set buzzer pin low in case it's high
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71 | PORTB &= 0x7F;
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72 | } |