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Tag: Open Hardware

BumbaBot-1

I got a simple motor from a broken domestic printer. It’s a Mitsumi m355P-9T stepping motor. Any other common stepping motor should fits. You can find one in printers, multifunction machines, copy machines, FAX, and such.

bumbabot v01

With a flexible cap of water bottle with a hole we make a connection between the motor axis and other objects.

bumbabot v01

bumbabot v01

With super glue I attached to the cap a little handcraft clay ox statue.

bumbabot v01

It’s a representation from a Brazilian folkloric character Boi Bumbá. In some traditional parties in Brazil, someone dress a structure-costume and dances in circular patterns interacting with the public.

776513346_c31db6843b_m

2246467684_49164d3397_m
Photos by Marcus Guimarães.

Controlling a stepper motor is not difficult.  There’s a good documentation on how to that on the Arduino Stepper Motor Tutorial. Basically it’s about sending a logical signal for each coil in a circular order (that is also called full step).

full step

Animation from rogercom.com.

stepper motor diagram

You’ll probably also use a driver chip ULN2003A or similar to give to the motor more current than your Arduino can provide and also for protecting it from a power comming back from the motor. It’s a very easy find this tiny chip on electronics or automotive  stores or also from broken printers where you probably found your stepped motor.

Arduino Stepper Motor UNL2003A

With a simple program you can already controlling your motor.

// Simple stepped motor spin
// by Silveira Neto, 2009, under GPLv3 license
// http://silveiraneto.net/2009/03/16/bumbabot-1/
int coil1 = 8;
int coil2 = 9;
int coil3 = 10;
int coil4 = 11;
int step = 0;
int interval = 100;
 
void setup() {
  pinMode(coil1, OUTPUT);
  pinMode(coil2, OUTPUT);
  pinMode(coil3, OUTPUT);
  pinMode(coil4, OUTPUT);
}
 
void loop() {
  digitalWrite(coil1, step==0?HIGH:LOW);
  digitalWrite(coil2, step==1?HIGH:LOW);
  digitalWrite(coil3, step==2?HIGH:LOW);
  digitalWrite(coil4, step==3?HIGH:LOW);
  delay(interval);
  step = (step+1)%4;
}


Writing a little bit more generally code we can create function to step forward and step backward.

My motor needs 48 steps to run a complete turn. So 360º/48 steps give us 7,5º per step. Arduino has a simple Stepper Motor Library but it doesn’t worked with me and it’s also oriented to steps and I’d need something oriented to angles instead. So I wrote some routines to do that.

For this first version of BumbaBot I mapped angles with letters to easy the communication between the programs.

motor angle step control

Notice that it’s not the final version and there’s still some bugs!

// Stepped motor control by letters
// by Silveira Neto, 2009, under GPLv3 license
// http://silveiraneto.net/2009/03/16/bumbabot-1/
 
int coil1 = 8;
int coil2 = 9;
int coil3 = 10;
int coil4 = 11;
 
int delayTime = 50;
int steps = 48;
int step_counter = 0;
 
void setup(){
  pinMode(coil1, OUTPUT);
  pinMode(coil2, OUTPUT);
  pinMode(coil3, OUTPUT);
  pinMode(coil4, OUTPUT);
  Serial.begin(9600);
}
 
// tells motor to move a certain angle
void moveAngle(float angle){
  int i;
  int howmanysteps = angle/stepAngle();
  if(howmanysteps<0){
    howmanysteps = - howmanysteps;
  }
  if(angle>0){
    for(i = 0;i<howmanysteps; i++){
      step(i%4);
      delay(delayTime);
    }
  }else{
    for(i=0;i<howmanysteps;i++){
      backstep(i%4);
      delay(delayTime);
    }
  }
}
 
// tells motor to move to a certain angle
void moveToAngle(float angle){
  moveAngle(angle-actualAngle());
}
 
// actual stepper motor angle
float actualAngle(){
  return step_counter*stepAngle();
}
 
// angle made by each step
float stepAngle(){
  return 360.0/steps;
}
 
// backward step
void backstep(int coil){
  digitalWrite(coil1, (coil==3)?HIGH:LOW);
  digitalWrite(coil2, (coil==2)?HIGH:LOW);
  digitalWrite(coil3, (coil==1)?HIGH:LOW);
  digitalWrite(coil4, (coil==0)?HIGH:LOW);
  step_counter--;
}
 
// forward step
void step(int coil){
  digitalWrite(coil1, (coil==0)?HIGH:LOW);
  digitalWrite(coil2, (coil==1)?HIGH:LOW);
  digitalWrite(coil3, (coil==2)?HIGH:LOW);
  digitalWrite(coil4, (coil==3)?HIGH:LOW);
  step_counter++;
}
 
void loop() {
  byte val;
  if(Serial.available()){
    val = Serial.read();
    switch (val) {
      case 'A': moveToAngle(  0); break;
      case 'B': moveToAngle( 45); break;
      case 'C': moveToAngle( 90); break;
      case 'D': moveToAngle(135); break;
      case 'E': moveToAngle(180); break;
      case 'F': moveToAngle(225); break;
      case 'G': moveToAngle(270); break;
      case 'H': moveToAngle(315); break;
      case 'I': backstep(1); backstep(0); break;
      case 'J': step(0); step(1);   break;
    }
    Serial.print(val);
  }
}

In another post I wrote how create a Java program to talk with Arduino. We’ll use this to send messages to Arduino to it moves. 

captura_de_tela-bumba01-netbeans-ide-65

[put final video here]

To be continued… :)

Morse Code Translator with Arduino

You write in your computer, sends a message thought USB and Arduino translates it into a Morse code.

Just a Arduino board with a buzzer connected at the digital output 12 (one wire in the ground and the other in the 12).

Arduino

I tried to make the code as general as possible so you can easily adapt it for anthers ways of transmitting a Morse code. To do that you just need to rewrite a few functions.

                                                  +-------------------+
                                                  | 3) Interpretation |
                                                  +-------------------+
                                                  |   2) Translation  |
+-------------------+                             +-------------------+
|     Computer      |<========USB (Serial)=======>|     1) Reading    |
+-------------------+                             +-------------------+

  1. Reads a character from Serial. Main function loop().
  2. Translate a ascii char into a Morse code using a reference table. A letter ‘K’ becomes a string word “-.-“. Function say_char().
  3. Interpret the Morse word as light and sound. Mostly at function say_morse_word(). The Interpretation needs 5 functions to say all Morse words, dot(), dash(), shortgap(), mediumgap() and intragap().

For a more details on Morse code I strongly recommend the English Wikipedia article on it.

int led = 13;                   // LED connected to digital pin 13
int buzzer = 12;                // buzzer connected to digital pin 12
int unit = 50;                  // duration of a pulse
 
char * morsecode[] = {
    "-----",  // 0
    ".----",  // 1
    "..---",  // 2
    "...--",  // 3
    "....-",  // 4
    ".....",  // 5
    "-....",  // 6 
    "--...",  // 7
    "---..",  // 8
    "----.",  // 9
    "---...", // :
    "-.-.-.", // ;
    "",       // < (there's no morse for this simbol)
    "-...-",  // =
    "",       // > (there's no morse for this simbol)
    "..--..", // ?
    ".--._.", // @
    ".-",     // A
    "-...",   // B
    "-.-.",   // C
    "-..",    // D
    ".",      // E
    "..-.",   // F
    "--.",    // G
    "....",   // H
    "..",     // I
    ".---",   // J
    "-.-",    // K
    ".-..",   // L
    "--",     // M
    "-.",     // N
    "---",    // O
    ".--.",   // P
    "--.-",   // Q
    ".-.",    // R
    "...",    // S
    "-",      // T
    "..-",    // U
    "...-",   // V
    ".--",    // W
    "-..-",   // X
    "-.--",   // Y
    "--.."    // Z
};
 
void setup() {
  pinMode(led, OUTPUT);
  pinMode(buzzer, OUTPUT);
  Serial.begin(9600);
}
 
void say_morse_word(char * msg){
  int index = 0;
  while(msg[index]!='\0'){
    // say a dash
    if(msg[index]=='-'){
      dash();
    }
    // say a dot
    if(msg[index]=='.'){
      dot();
    }
    // gap beetween simbols
    intragap();
    index++;
  }
}
 
// beep
void beep(int time){
  int i;
  int t = 100; // period of the wav. bigger means lower pitch.
  int beepduration = (int)((float)time/t*1800);
  digitalWrite(led, HIGH);
  for(i=0;i<beepduration;i++){
    digitalWrite(buzzer, HIGH);
    delayMicroseconds(t);
    digitalWrite(buzzer, LOW);
    delayMicroseconds(t);
  }
  delay(time);
}
 
// silence
void silence(int time){
  digitalWrite(led, LOW);
  delay(time);
}
 
// general procedure for .
void dot() {
  beep(unit);
}
 
// general procedure for -
void dash() {
  beep(unit*3);
}
 
// gap between dots and dashes
void intragap() {
  silence(unit);
}
 
// gap between letters
void shortgap() {
  silence(3*unit);
}
 
// gap be  tween words
void mediumgap() {
  silence(7*unit);
}
 
void say_char(char letter){
  if((letter>='0')&&(letter<='Z')&&(letter!='<')&&(letter!='>')){
    Serial.print(morsecode[letter-'0']);
    Serial.print(' ');
    say_morse_word(morsecode[letter-'0']);
    shortgap();
  } else {
    if(letter==' '){
      Serial.print(" \\ ");
      mediumgap();
    }else{
      Serial.print("X");
    }
  }
}
 
void loop(){
  if(Serial.available()){
    say_char((char)Serial.read());
  }
}

Additionally you can put another function to say entire strings, like say_string(“HELLO WORLD”)

void say_string(char * asciimsg){
  int index = 0;
  char charac;  
  charac = asciimsg[index];
  while(charac!='\0'){
    say_char(morsecode[charac-'0']);
    Serial.println(morsecode[charac-'0']);
    charac = asciimsg[++index];
    shortgap();
  }
}

You can use the Arduino IDE itself or any other program that talks with the serial port USB.

arduino interface