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[on:]

Dear Diyers,

I would like to control the JUNO60 in MIDI
This old syntheziser use DCB protocol
http://en.wikipedia.org/wiki/Digital_Control_Bus

i connect the arduino like this
-DCB Tx Data -----> Arduino Rx
 -DCB ground ------> Arduion Ground

I use this program to read the data who send the juno 60

Code:

int Led = 13;
int data = 0;
int count=0;


///////////////////////////////////////////////////////////////
//Initialisation de la sorite de la Led et du port Rx en Midi//
void setup() {

}
////////////////////////////////////////////////////////////////
///////////////////////debut de la boucle///////////////////////
void loop() {
  Serial.begin(31250);
  delay(100);
  if(Serial.available() > 0){// un info est elle presente en Rx
    data = Serial.read();// enregistrer cette info dans la variable Data
    
    Serial.begin (9600);
    
    Serial.print (data, HEX);
    Serial.println (" ");
    count ++;
    if (count == 7){
      Serial.print("/n");
      count =0;
    }
  }
}

That what i read on the serial monitor



I don't understand this data because at the beginning the data seem to ok and when i try to push a key the datra change and never be the same as the beginning
Is there anybody who are "friendly" with the type of protocol or maybe i dont interface it correctly

Thank you for your help
Xarolium

[Reply #1 on:]

Hi,

I don't know the DVB protocol but are you sure about your baud rate ?
Because usually this kind of bad data can comes from incorrect baud rate

Edit : after checking the wikipedia page you added, it seems that the protocol have 2 stop bit.
"LSB first, 8 data bits, 2 stop bits, odd parity, and a Baud rate of 31.25kHz."

This could be the cause of your data errors
There is a post on midibox forum about this protocol (but no solution) you can maybe find useful info :
http://midibox.org/forums/topic/5013-midi-dcb/

xray303

[Reply #2 on:]

thank you for your help Xray303

I learned a little bit more of the UART protocol
and it work like that.
A byte is composing with:
-first one start bit = 0
-after Data bits between 5 and 9
-then a parity bit
-finaly one stop bit = 1

the different between  the DCB protocol and UART is that the start in DCB is 1 and stop Bit is 0
Do you think it's possible to change this on the Arduino UART.

[Reply #3 on:]

Hi,

It's a good question, i never tried (never needed) maybe some  Arduino Guru here could respond to that.

you can try to look at this it could help :
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1243894373/15
http://code.google.com/p/arduino/issues/detail?id=573
http://www.arduino.cc/en/Tutorial/SoftwareSerial

[Reply #4 on:]

thank you
the last link is very useful
on this page he said:

Definitions Needed:

#define bit9600Delay 84  
#define halfBit9600Delay 42
#define bit4800Delay 188
#define halfBit4800Delay 94

But how he can find 84 microseconds to generate 9600baud
f=1/T       F= 1/0,000084 = 11905 hz approximately

How can i find the right frequency to generate 31250baud ?
Maybe he add the time of each action on his fonction , i'm right??

Now, with your help i know what i need to do to send data in my JUNO60
Arduino must generate a clock at 31250hz on one PIN
a second PIN must send DATA (Start bit, Data Bits,Parity Bit and Stop Bit) in Serial at the same frequency and synhcro with the clock
And a third PIN to latch the hardwareflow control.
Then i could use this part of code to generate the right "polarity" of my bit

Code:

void SWprint(int data)
{
  byte mask;
  //startbit
  digitalWrite(tx,LOW);
  delayMicroseconds(bit9600Delay);
  for (mask = 0x01; mask>0; mask <<= 1) {
    if (data & mask){ // choose bit
     digitalWrite(tx,HIGH); // send 1
    }
    else{
     digitalWrite(tx,LOW); // send 0
    }
    delayMicroseconds(bit9600Delay);
  }
  //stop bit
  digitalWrite(tx, HIGH);
  delayMicroseconds(bit9600Delay);
}