150 lines
4.1 KiB
Markdown
Executable File
150 lines
4.1 KiB
Markdown
Executable File
## Noise Toys
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To turn a blinky LED program into a simple square-wave synthesizer, plug
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a speaker into PB4 and ground (where the LED was before), and turn up
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the frequency.
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The code is largely the same, just toggling a pin on and off, but now
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doing it at different speeds (for different tones) and for differing
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time periods (notes duration).
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## squareOne.c
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<nowiki>
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/* Makes a quick square wave for noise-making experimentation. */
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#include <inttypes.h>
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#include <avr/io.h>
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#define F_CPU 16000000L /* really? tested with the scope for Tiny45 */
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#include <util/delay.h>
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void init(void){
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DDRB |= _BV(PB4);
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}
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int main(void){
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uint8_t i, j, k;
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uint16_t wavelength;
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init();
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while(1){
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for (k = 10; k > 3; k--){ /* pitch multiplier: makes different notes */
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wavelength = 20*k;
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for (j=0; j < 200/k; j++){
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/* number of cycles at each pitch: controls speed of loop */
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PORTB |= _BV(PB4);
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for (i=0; i < wavelength; i++) /* on for 20*wavelength microsecs */
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_delay_us(20); /* loop needed b/c each call to
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the delay function can't
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delay all that long before
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it overflows */
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PORTB &= ~_BV(PB4); /* off for 20*wavelength microsecs */
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for (i=0; i < wavelength; i++)
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_delay_us(20);
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}
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}
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}
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}
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</nowiki>
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## spacePhaser.c
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<nowiki>
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/* Starts with a very short pulse (high-frequency) and drops rapidly. */
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#include <inttypes.h>
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#include <avr/io.h>
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#define F_CPU 16000000L /* really? tested with the scope */
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#include <util/delay.h>
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void init(void){
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DDRB |= _BV(PB4);
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}
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int main(void){
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uint8_t i, j, k;
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uint16_t wavelength;
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init();
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while(1){
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for (k = 3; k < 120; k++){ /* pitch multiplier: makes different notes */
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wavelength = k;
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for (j=0; j < 200/k; j++){
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/* number of cycles at each pitch: controls speed of loop */
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PORTB |= _BV(PB4);
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for (i=0; i < wavelength; i++) /* on for 20*wavelength microsecs */
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_delay_us(20); /* loop needed b/c each call to
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the delay function can't
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delay all that long before
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it overflows */
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PORTB &= ~_BV(PB4); /* off for 20*wavelength microsecs */
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for (i=0; i < wavelength; i++)
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_delay_us(20);
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}
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}
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for (j=0; j < 60; j++){ /* with delay between shots */
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for (i=0; i < 250; i++)
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_delay_us(200);
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}
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}
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}
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</nowiki>
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## chaosEngine.c
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<nowiki>
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/* Now the frequency of the wave is a crazy function. */
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#include <inttypes.h>
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#include <avr/io.h>
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#define F_CPU 16000000L /* really? tested with the scope */
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#include <util/delay.h>
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void init(void){
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DDRB |= _BV(PB4);
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}
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int main(void){
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uint8_t i, j, k;
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uint16_t wavelength;
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init();
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while(1){
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wavelength = (13 * wavelength + 1) % 123 + 100;
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for (j=0; j < 30; j++){
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/* number of cycles at each pitch */
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PORTB |= _BV(PB4);
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for (i=0; i < wavelength; i++) /* on for 20*wavelength microsecs */
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_delay_us(20); /* loop needed b/c each call to
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the delay function can't
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delay all that long before
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it overflows */
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PORTB &= ~_BV(PB4); /* off for 20*wavelength microsecs */
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for (i=0; i < wavelength; i++)
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_delay_us(20);
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}
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}
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for (j=0; j < 60; j++){ /* longer delay between shots */
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for (i=0; i < 250; i++)
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_delay_us(200);
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}
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}
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</nowiki>
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[Category: AVR Tutorial](Category:_AVR_Tutorial "wikilink") |