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Editing code with suggested changes (still not working)

edited Aug 9, 2014 at 23:39

Controlling Floppy Disk Drive with Arduino

I am having problems controlling a 3.5" Floppy Disk Drive with an Arduino Uno.

I have the floppy disk drive powered with a computer power supply that is switched on, and the Arduino powered by my computer's USB. I have cut apart the ribbon of a 34-pin IDC connector to be able to route the pins to my Arduino. I am able to turn the floppy disk motor on and move the read/write head back and forth, but I am never able to read any pulses from the Track-0 or Index pins.

I have pins 7, 15, 17, 19, and 25 from the floppy all grounded to my Arduino, and I have pins 8, 16, 18, 20, and 26 from the floppy connected to my arduino as output pins so I can control the drive.

I am expecting the Index to pulse when the disk motor makes a rotation, and for Track 0 to change when I am at the outside of the disk, but they are both always LOW. Am I missing something?

Here is the spec I found for the back of the floppy disk unit

    2   /REDWC  Input Density Select
    4   n/c N/A Reserved
    6   n/c N/A Reserved
    8   /INDEX  Output Index
    10  /MOTEA  Input Motor Enable A 
    12  /DRVSB  Input Drive Sel B
    14  /DRVSA  Input Drive Sel A 
    16  /MOTEB  Input Motor Enable B
    18  /DIR    Input Direction
    20  /STEP   Input Step 
    22  /WDATE  Input Write Data
    24  /WGATE  Input Floppy Write Enable
    26  /TRK00  Output Track 0
    28  /WPT    Output Write Protect
    30  /RDATA  Output Read Data
    32  /SIDE1  Input  Head Select
    34  /DSKCHG Output Disk Change/Ready

Here a schematic of what I have hooked up (The breadboard in this circuit diagram represents the IDC connector that is plugged into the 3.5" floppy drive.)

Floppy & Arduino Connections

Here is a photo of the IDC Connector and I labelled which wires are connected to the Arduino.

Labelled IDC Connector

Here's the code I am running.

//constants
static const int IN = LOW;
static const int OUT = HIGH;
static const int pulseDelayTime = 6;

//pins
int indexPin = 2; //8 on the drive INDEX
int track0Pin = 3; //26 on the drive. TRACK 0
int dirPin = 6; //18 on the drive. DIRECTION
int stepPin = 7; //20 on the drive. STEP
int motorEnableBPin = 9; //16 on the drive. MOTOR ENABLE B

unsigned long motorSpinTime = 1000UL; //in ms


void setup() {

  //initial delay
  delay(3000);

  //setup serial monitor
  Serial.begin(9600);      

  //setup pins.
  pinMode(dirPin, OUTPUT);
  pinMode(stepPin, OUTPUT);
  pinMode(motorEnableBPin, OUTPUT);
  pinMode(indexPin, INPUT);
  pinMode(track0Pin, INPUT);

  //turn the motor off initially
  digitalWrite(motorEnableBPin, HIGH);

  //print state here.
  printState("Setup done.");
  
  //spin the disk some.
  printState("Begin to spin motor");
  spinMotorForThisManyMs(motorSpinTime);
  spinMotorForThisManyMs(motorSpinTime);
  printState("Done spinning motor");

  //step read/write head all the way in.
  stepAllTheWayIn();
  
  //spin the disk some more.
  printState("Begin to spin motor");
  spinMotorForThisManyMs(motorSpinTime);
  spinMotorForThisManyMs(motorSpinTime);
  printState("Done spinning motor");
  
  //step read/write head all the way out.
  stepAllTheWayOut();
  
  //spin the disk even more.
  printState("Begin to spin motor");
  spinMotorForThisManyMs(motorSpinTime);
  spinMotorForThisManyMs(motorSpinTime);
  printState("Done spinning motor");
  
  //never completes.
  waitForIndex();
}

void loop() {
}

//spins the disk motor for a number of ms and prints the state
void spinMotorForThisManyMs(unsigned long msToSpin) {

  //start spinning
  digitalWrite(motorEnableBPin,LOW);

  //delay.. keep printing the state
  unsigned long maxTimeMs = millis() + msToSpin;  
  while(millis() < maxTimeMs ) {
    printState("Spinning");    
  }

  //stop spinning
  digitalWrite(motorEnableBPin,HIGH);
}



//step the read/write head all the way to the center
void stepAllTheWayIn() {
  for(int i=0;i<100;i++) {
    printState("Stepping In");
    stepInALittle();
  }
}

//step the read/write head all the way to the outside
void stepAllTheWayOut() {
  for(int i=0;i<100;i++) {
    printState("Stepping Out");
    stepOutALittle();
  }
}

//print the state of the index and track
void printState(const char* charPrint) {
  Serial.print(" Index:");
  Serial.print(digitalRead(indexPin));
  Serial.print(" Track:");
  Serial.print(digitalRead(track0Pin));
  Serial.print(" ");
  Serial.println(charPrint);
}

//move the head towards the outside a little
void stepOutALittle() {
  digitalWrite(dirPin,HIGH);
  stepPulse();
}

//move the head towards the center a little
void stepInALittle() {
  digitalWrite(dirPin,LOW);
  stepPulse();
}

//pulse the step pin
void stepPulse() {
  digitalWrite(stepPin,LOW);
  delay(pulseDelayTime);
  digitalWrite(stepPin,HIGH);
}

//waits for the index to trigger. this never gets completed.
void waitForIndex() {
  
  printState("beginning to wait for index pin to pulse");
  
  //start spinning
  digitalWrite(motorEnableBPin,LOW);
  
  //wait for pulse
  while(digitalRead(indexPin));
  //wait for end of pulse 0
  while(!digitalRead(indexPin));
  
  printState("end of waiting for index pin to pulse");
  
  //stop spinning
  digitalWrite(motorEnableBPin,HIGH);
}

Here is the output I am getting.

 Index:0 Track:0 Setup done.
 Index:0 Track:0 Begin to spin motor
 Index:0 Track:0 Spinning
 Index:0 Track:0 Spinning
 Index:0 Track:0 Spinning
 Index:0 Track:0 Spinning
 Index:0 Track:0 Spinning
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 Index:0 Track:0 Done spinning motor
 Index:0 Track:0 Stepping In
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 Index:0 Track:0 Stepping In
 Index:0 Track:0 Begin to spin motor
 Index:0 Track:0 Spinning
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 Index:0 Track:0 Done spinning motor
 Index:0 Track:0 Stepping Out
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 Index:0 Track:0 Stepping Out
 Index:0 Track:0 Stepping Out
 Index:0 Track:0 Stepping Out
 Index:0 Track:0 Stepping Out
 Index:0 Track:0 Begin to spin motor
 Index:0 Track:0 Spinning
 Index:0 Track:0 Spinning
 Index:0 Track:0 Spinning
 Index:0 Track:0 Spinning
 Index:0 Track:0 Spinning
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 Index:0 Track:0 Spinning
 Index:0 Track:0 Spinning
 Index:0 Track:0 Done spinning motor
 Index:0 Track:0 beginning to wait for index pin to pulse

arduino-uno hardware

asked Aug 9, 2014 at 21:15

Jeff Lett