Thursday, 21 May 2015

Midi controlled Dub siren

Midi controlled Dub siren (basic proof of concept)

Tuesday, 5 May 2015

Midi Shield Controller Dub Siren AVR/Arduino test

Monday, 4 May 2015

Using Cubase LE as a debugger for my code

Using Cubase LE as a debugger for my code

While testing some code for some midi controllers i thought of using Cubase to better help me debug it.
* Black is received data, blue when negative bend, red when positive and light green/blue is no update on data ( does not reset automatically until told to).
Using Pitch bend in this emoticon

* Black is received data, Blue when negative bend, Red when positive and light green/blue is no update on data ( doesnt reset automatically until told to).
Using Pitch bend in this case.

Wednesday, 29 April 2015

chipKIT DP32 Simple dub Siren Code

Sampling Rate 22.050 kHz, with 12 bit DAC MCP4725 ( breakout board)
Using button 2(Pin 17) on DP32 and Variable pot (A2).
For the signal out, the ac coupling circuit from previous post is necessary.
*Check also I2C Speed post HERE

#include <sys/attribs.h>
#include <Wire.h>
#define MCP4725_DID 96 // define device id - see datasheet
#define SYS_FREQ            (40000000L)
#define PB_DIV              4
#define PRESCALE            2
#define FRQ                 22050 //21504
#define T1_TICK             (SYS_FREQ/PB_DIV/PRESCALE/FRQ)

#define WAVE_SAMPLES 256
const int buttonPin = 17; 
// variables will change:
int buttonState = 0;         // variable to read the pushbutton status
uint8_t playOn=0;            // Variable of play state/button state
volatile uint16_t a;
uint16_t b;
uint16_t d;
uint16_t e=0;
uint16_t inc;
uint8_t statedown=0;
boolean c;
boolean togg;
uint16_t sineData [WAVE_SAMPLES];

void setup()
  // Serial.begin(57600);
  pinMode(A2, INPUT); //
  pinMode(13, OUTPUT); //
  //set pins to output because they are addressed in the main loop
  sine ();  
  Wire.begin() ;

void loop()
  uint16_t aIn =analogRead(A2);
  inc=aIn >>4;
  buttonState = digitalRead(buttonPin);

  // check if the pushbutton is pressed.
  // if it is, the buttonState is HIGH:
  if (buttonState == HIGH) {  
    // play is On    
    // play is Off

  if(c !=togg){


      a = a++  ;
      a+= (inc+(e >>4));
        // ramp up or down variables
        if (statedown==0){
          if (e==0){
      Wire.beginTransmission(MCP4725_DID); //device adress
      Wire.send(64);                     // cmd to update the DAC
      Wire.send(sineData[a] >> 4);        // the 8 most significant bits...
      Wire.send((sineData[a] & 15) << 4); /* the 4 least significant bis...*/

// call interrupt handling vector
extern "C" {

  void __ISR(16, ipl6) int1Handler(void) 
    togg= !togg;
    IFS0CLR = 0x80000;// Clear the T4 interrupt flag Bit 19

void initTmr(){
  T4CON=0x0; //Stop timer and clear registers
  T4CONSET = 0x0010; // set prescalar 1:2 ox60 to experiment
  TMR4 = 0x0; //Clear Timer 4 register
  PR4 = T1_TICK ; //0x17; // set timer to 23 
  IFS0CLR = 0x80000;// Clear the T4 interrupt flag Bit 19
  IPC4SET = 0x00000016;// Interrupt priority 5, 2
  IEC0SET = 0x80000;// Enable T4 interrupt Bit 19
  T4CONSET = 0x8000;// Enable Timer4  
void sine (){
  uint16_t i;
    b = 2047*sin((2*PI/WAVE_SAMPLES)*i);
    sineData [i]=b;

ChipKIT DP32 I2C Bus Speed with a MCP4725 DAC

Both arduino and MPIDE seem to have the I2C bus speed set to 100 kHz by default. So, here it is how to change it to 400kHz.
Inside the MPIDE folder, go to hardware\pic32\libraries\Wire\utility.
Inside file twi.h Find the string #define TWI_FREQ 100000 and change it to:  #defineTWI_FREQ 400000.
In my simple test i went from a 20Hz sinewave to a 72Hz just by effecting this change to the bus speed.
On the DP32 Board, SDA is assigned to Pin RB9 and SCL to Pin RB8.

Sunday, 26 April 2015

Atmega 328/Uno simple Dub synth

R2R DAC -view picture in the end of article. Usa same principle to build an 8 Bit R2R DAC from D0 to D7

Some intial test sounds out of a Uno mini Dub synth. The file was  recorded , unfiltered ( 0 to 5V) and lined out of a guitar amp in clean mode. - Some noise was introduced by the guitar amd as well.
Next step of project is to AC couple signal also with a suitable RC filter, decoupling capacitors and prepare the rest of line out for use with sound gear.
The limitations of the ATMega328 are big compared to the DUE for this kind of project, but good enough to get some interesting sounds, plus it can also double as a dub siren . Sr @ 16kHz-8Bit Dac

You can download /preview  it in mp3 here

a 6 bit R2R Dac

ac coupling of a 0-5 V signal from Atmega328

Example of a signal with dc offset, and after the passive filter

Having  a 0 to 5 V signal generated digitally with a R2R 8 bit dac, i needed to remove the offset introduced . This is a simple way and also makes it to "audio friendly" .

Low pass filter and ac coupling circuit block used in one of my projects