neingeist/arduinisten
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slightly less b0rken

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This commit is contained in:
entropia 2010-04-01 00:40:17 +02:00
parent 06192bb337
commit 1c6ccf8eaf
1 changed files with 78 additions and 35 deletions
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113
projekte/soundz/karplus_strong_totally_borken/karplus_strong_totally_borken.pde
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@ -23,42 +23,11 @@ void setup() {
// Set initial pulse width to the first sample.
OCR2A = 0;
// DEBUG
Serial.begin(9600);
}
int play (uint16_t f, uint8_t T) {
sendKarplusStrongSound(f, T);
}
// http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1249193795
int sendKarplusStrongSound(const uint16_t f /*Hz*/, const uint8_t T /*sec*/) {
const uint8_t N = 32;
const uint32_t sr = f * N; // sample rate: 800(25Hz)..47619(1488Hz)
int16_t buf[N];
for (uint8_t i=0; i<N; i++)
buf[i] = (int16_t) random(-32768,32767);
uint8_t bh = 0;
const int Tloop = 60; // or is it more?
const int dt = 16000000/sr - Tloop;
for (uint32_t i=sr*T/2; i>0; i--) {
const int8_t v = (int8_t) (buf[bh] >> 8);
OCR2A = v;
_delay_us(dt); // or do something else for <dt> usecs
uint8_t nbh = bh!=N-1 ? bh+1 : 0;
int32_t avg = buf[bh] + (int32_t)buf[nbh];
//avg = (avg << 10) - avg; // subtract avg more than once to get faster volume decrease
avg = (avg << 10) - avg -avg;
buf[bh] = avg >> 11; // no division, just shift
bh = nbh;
}
}
// Frequencies (in Hz) of notes
#define FSH_4 370
#define A_4 440
@ -72,6 +41,81 @@ int sendKarplusStrongSound(const uint16_t f /*Hz*/, const uint8_t T /*sec*/) {
#define REST 0
int play (uint16_t f, uint8_t T) {
#define MAGIC_TUNE_FAC 3
if (f == REST) {
_delay_ms(T*1000/16*MAGIC_TUNE_FAC);
} else {
sendKarplusStrongSound(f, T*MAGIC_TUNE_FAC);
}
}
// http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1249193795
int sendKarplusStrongSound(uint16_t f /*Hz*/, uint8_t T /* 1/16 sec*/) {
uint32_t sr = 11025;
uint8_t N = sr/f;
//uint8_t N=32;
//uint32_t sr = (uint32_t) N*f;
Serial.print("N = ");
Serial.print(N, DEC);
Serial.println();
unsigned long millis_alt = millis();
int buf[N];
for (uint8_t i=0; i<N; i++)
buf[i] = random(65536);
uint8_t bh = 0;
int Tloop = 18
; // FIXME: tune
int dt = (1000000ul)/sr - Tloop;
Serial.print("dt = ");
Serial.print(dt, DEC);
Serial.println();
for (uint32_t i=sr*T/16; i>0; i--) {
// current amplitude to play is the highest byte of buf[bh]
#if 1
OCR2A = buf[bh] >> 8;
#else
OCR2A = buf[bh];
#endif
// delay or do something else for <dt> usecs
_delay_us(dt);
// calculate avg between current buf[bh] and next sample buf[nbh]
uint8_t nbh;
if (bh < N-1) {
nbh = bh + 1;
} else {
nbh = 0;
}
// calculate avg
unsigned long avg = ((unsigned long) buf[bh] + (unsigned long) buf[nbh])/2;
// with gain<1 (1020/1024 ~ 0.996)
avg *= 1020;
avg /= 1024;
// put back in buffer
buf[bh] = (int) avg;
bh = nbh;
}
Serial.print("T_real = ");
Serial.print(millis() - millis_alt, DEC);
Serial.print(", T/16 = ");
Serial.print(T*1000/16, DEC);
Serial.println();
}
void loop() {
// Axel F
play(FSH_4, 2);
@ -100,5 +144,4 @@ void loop() {
play(GSH_4, 2);
play(FSH_4, 6);
play(REST, 12);
delay(100);
}