Third prototype: one voice!
Check this video on vimeo: http://vimeo.com/12988327 :)
This is the third prototype of my DIY synthesizer. I’m using a 82c54 16-bit timer chip for the voice (one chip has three timers, so three voices should be possible). This chip divides a master clock signal (usually in the Mhz range) through a programmable 16-bit value to create a audible frequency.
An Arduino Duemilanove interprets the midi (CNY17) and feeds a divider value via a shift register (74hc595) to the 82c54 voice. The crystal oscillator clock ticks at 8Mhz so for a 440Hz pulse waveform (central A) the division value is 18182. This prototype cannot produce notes below midinote 47 (B) because of it’s maximum divider value (16-bit = 65.536). Future prototypes will use a clock divider (arduino itself?)
Oh, my synth-playing-skills are well below par ;)
Very much inspired by the Roland Jupiter / Juno series.
This is the prototype from the previous post, with the midi in hardware solution from tetracon (arduino forum).
[][1]
Timothy Twillman has developed a great Arduino midi library. Very easy to implement, exactly what I needed. Check it out.
For each midi note, I pre-calculated the least and the most significant byte. The prototype code (very ugly):
#include "Midi.h"
int midi_divides_lsb[] = {66, 182, 65, 33, 183, 116, 192, 11, 222, 186, 44, 195, 33, 222, 160, 16,
221, 186, 94, 135, 240, 93, 150, 99, 144, 239, 80, 136, 111, 221, 176, 195,
248, 47, 75, 49, 200, 247, 168, 196, 55, 239, 216, 226, 252, 23, 37, 25, 228,
124, 212, 226, 156, 247, 236, 113, 126, 12, 19, 140, 114, 190, 106, 113, 206,
124, 118, 184, 63, 6, 9, 70, 185, 95, 53, 56, 103, 190, 59, 220, 159, 131, 133,
163, 221, 47, 154, 28, 179, 95, 29, 238, 208, 193, 194, 210, 238, 24, 77, 142,
218, 47, 143, 247, 104, 225, 97, 233, 119, 12, 167, 71, 237, 152, 71, 252, 180, 112,
49, 244, 188, 134, 83, 36, 246, 204, 164, 126};
int midi_divides_msb[] = {3822, 3607, 3405, 3214, 3033, 2863, 2702, 2551, 2407, 2272, 2145, 2024,
1911, 1803, 1702, 1607, 1516, 1431, 1351, 1275, 1203, 1136, 1072, 1012,
955, 901, 851, 803, 758, 715, 675, 637, 601, 568, 536, 506, 477, 450,
425, 401, 379, 357, 337, 318, 300, 284, 268, 253, 238, 225, 212, 200,
189, 178, 168, 159, 150, 142, 134, 126, 119, 112, 106, 100, 94, 89, 84,
79, 75, 71, 67, 63, 59, 56, 53, 50, 47, 44, 42, 39, 37, 35, 33, 31, 29,
28, 26, 25, 23, 22, 21, 19, 18, 17, 16, 15, 14, 14, 13, 12, 11, 11, 10,
9, 9, 8, 8, 7, 7, 7, 6, 6, 5, 5, 5, 4, 4, 4, 4, 3, 3, 3, 3, 3, 2, 2, 2, 2};
class MyMidi : public Midi {
public:
// Need this to compile; it just hands things off to the Midi class.
MyMidi(HardwareSerial &s) : Midi(s) {}
void handleNoteOn(unsigned int channel, unsigned int note, unsigned int velocity)
{
digitalWrite(13, HIGH);
data_transfer(midi_divides_lsb[note],midi_divides_msb[note]);
// Serial.println(note);
// Serial.print(midi_divides_lsb[note]);
// Serial.print(" - ");
// Serial.println(midi_divides_msb[note]);
}
void handleNoteOff(unsigned int channel, unsigned int note, unsigned int velocity)
{
digitalWrite(13, LOW);
}
/* You can define any of these functions and they will be called when the
matching message type is received. Otherwise those types of Midi messages
are just ignored.
For C++ folks: these are all declared virtual in the base class
void handleNoteOff(unsigned int channel, unsigned int note, unsigned int velocity);
void handleNoteOn(unsigned int channel, unsigned int note, unsigned int velocity);
void handleVelocityChange(unsigned int channel, unsigned int note, unsigned int velocity);
void handleControlChange(unsigned int channel, unsigned int controller, unsigned int value);
void handleProgramChange(unsigned int channel, unsigned int program);
void handleAfterTouch(unsigned int channel, unsigned int velocity);
void handlePitchChange(unsigned int pitch);
void handleSongPosition(unsigned int position);
void handleSongSelect(unsigned int song);
void handleTuneRequest(void);
void handleSync(void);
void handleStart(void);
void handleContinue(void);
void handleStop(void);
void handleActiveSense(void);
void handleReset(void);
*/
};
//Pin connected to ST_CP of 74HC595
int latchPin = 8;
//Pin connected to SH_CP of 74HC595
int clockPin = 12;
////Pin connected to DS of 74HC595
int dataPin = 11;
int statusled = 13;
int incomingByte = 0; // for incoming serial data
MyMidi midi(Serial);
void setup() {
//set pins to output so you can control the shift register
pinMode(latchPin, OUTPUT);
pinMode(clockPin, OUTPUT);
pinMode(dataPin, OUTPUT);
pinMode(statusled, OUTPUT);
digitalWrite(statusled,HIGH);
// init 8254 control ports 2,3,4
pinMode(2, OUTPUT); // WR
digitalWrite(2, HIGH); // disabled
pinMode(3, OUTPUT); // A0
pinMode(4, OUTPUT); // A1
digitalWrite(3, LOW);
digitalWrite(4, LOW);
midi.begin(0);
firstrun();
//settozero();
}
void loop() {
// if(Serial.available() > 0)
// {
// incomingByte = Serial.read();
// if (incomingByte == 49) { // 1
// firstrun();
// }
// }
midi.poll();
}
void firstrun() {
// control word sequence
Serial.println("A0A1 -> 1");
digitalWrite(3, HIGH);
digitalWrite(4, HIGH);
Serial.println("2 low");
digitalWrite(2, LOW);
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, LSBFIRST, B01101100);
digitalWrite(latchPin, HIGH);
Serial.println("595 loaded");
Serial.println("2 high");
digitalWrite(2, HIGH);
// end control word sequence
// start data transfer, LSB MSB
// 18181 for 400hz
data_transfer( 5, 71);
}
void data_transfer(int LSB, int MSB) {
Serial.println("A0A1 -> 0");
digitalWrite(3, LOW);
digitalWrite(4, LOW);
Serial.println("2 low");
digitalWrite(2, LOW);
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, MSBFIRST, LSB);
digitalWrite(latchPin, HIGH);
Serial.println("595 LSB");
Serial.println("2 high");
digitalWrite(2, HIGH);
Serial.println("2 low");
digitalWrite(2, LOW);
digitalWrite(latchPin, LOW);
shiftOut(dataPin, clockPin, MSBFIRST, MSB);
digitalWrite(latchPin, HIGH);
Serial.println("595 MSB");
Serial.println("2 high");
digitalWrite(2, HIGH);
}