Bajdi electronics

Not have much time to play with Arduino or robots the last days. But I have been busy designing a couple of PCB’s in Eagle. Eagle is a software program to draw schematics and then turn them in to PCB’s. You can then sent the drawing of the PCB to a company like Iteadstudio that will make the PCB for you. There are many other companies that will do this for you, I’ve chosen Iteadstudio because they were the cheapest I could find. They are located in China so it does take some time until you receive your PCB’s. The first PCB I designed is an “undershield” for an Arduino Nano. Basically it’s a board where you can plug an Arduino Nano on. It has a lot of pins to easily connect sensors and servos. The most advanced feature of the board is that it has an LM2576 3A 5V regulator on it. It bypasses the small 5V regulator on the Nano. That way I can use it to power the continuous servos on my line following robot. Eagle is not that hard to learn if you want to design a simple board. After watching some Eagle tutorials on Youtube I managed to design my undershield PCB and order it. I just hope that it will work 🙂 Will have to wait and see, I should have the PCB’s in 1 or 2 weeks time.

My second PCB design is based on the Atmel ATmega328P-PU, the same microcontroller as the one on the Arduino Uno. It’s powered from the same 5V 3A regulator as I used on my undershield. I bought a whole bunch of these regulators from Tayda electronics. I don’t have any direct plans with the board but I wanted to to try designing my own Arduino. It doesn’t have an USB port but it does have an FTDI serial header. I would need to buy a FTDI cable to upload sketches to it. The board is not Arduino shield compatible since it is a single layer PCB with only through the hole components. It took me many hours to route all the traces without using any vias (connection on top of the board).

Playing with Dagu Rover and gripper from Bajdi on Vimeo.

Finally got around to make a sketch to remote control my Rover 5 and gripper. I started with a sketch to control just the gripper with a 2 axis joystick and 2 buttons to open and close the gripper. While testing that sketch I made a little mistake that stripped the gears of the claw servo. Luckily I received a new servo very fast and while I was at it I ordered a spare one 🙂 Most servos can move 180 degrees and if you have mounted a servo so it can only move less then 180 degrees because of mechanical reasons it’s best to limit the movement of the servo in software. I hadn’t thought of that and my code sent the servo to a position it physically couldn’t go to and that stripped the metal gears of the servo. Luckily these little Chinese servos are pretty cheap so it wasn’t a big loss. It’s a lesson learnt.

I did have some more problems testing the gripper. When I use the sketch with only the code to control the gripper the servos move very fast and I had to slow them down in the sketch else I couldn’t control them accurately. When I added that sketch to my existing remote control sketch of my rover the servos where very slow so I had to change it so they moved faster. To power the 3 servos I use a very cheap 4A UBEC (5V regulator). I soldered a bunch of pins to a small PCB to connect the UBEC to the servos and the micro controller. I’ve even added a big capacitor to the board to help keep the noise of the UBEC under control. I was a bit worried that it will interfere with my 2,4GHz wireless nRF24L01 module. Since I’ve added the gripper my Lipo batteries seem to go flat a lot faster, those 3 servos must draw a considerate amount of power.

I used my self made remote control (Arduino Uno + joystick shield + nRF24L01 + I2C 4×20 LCD) to control the Rover and gripper. The LCD shows the current of the 4 motors and the battery voltages of the battery in the remote and the rover.

Here are the sketches I’ve used in the video:

The sketch that went in my self made remote control:

// http://www.bajdi.com
// Sketch to remote control Dagu Rover 5 with 3 DIF gripper
// Nrf24L01 connected to Arduino Uno
// Nrf24L01 connection details http://arduino-info.wikispaces.com/Nrf24L01-2.4GHz-HowTo
// 4 x 20 I2C LCD
// Transmit analog values from joystick and the state of 3 buttons to the Rover 5 using RF24 library.
// Receive 4 floats (current values from the motors) and the battery voltage from the Rover 5 and display it on the LCD

#include &lt;SPI.h&gt;
#include &lt;nRF24L01.h&gt;
#include "RF24.h"
#include &lt;Wire.h&gt;
#include &lt;LiquidCrystal_I2C.h&gt;
#include &lt;Bounce.h&gt;

LiquidCrystal_I2C lcd(0x27,20,4); // set the LCD address to 0x27

RF24 radio(8,9);

const uint64_t pipes[2] = { 
  0xF0F0F0F0E1LL, 0xF0F0F0F0D2LL };

int joystick[5];
float rover[5];
float batr;

const int z = 2;
const int clawopen = 3;
const int clawclose = 6;
int roverState;         // the rover state of the output pin

Bounce bouncerz = Bounce( z, 10 );

long previousMillis = 0;
const int interval = 25;

void setup(){
  Serial.begin(9600);
  pinMode(z, INPUT);
  digitalWrite(z, HIGH);
  pinMode(clawopen , INPUT);
  pinMode(clawclose , INPUT);
  digitalWrite(clawopen, HIGH);
  digitalWrite(clawclose, HIGH);
  radio.begin();
  radio.openWritingPipe(pipes[0]);
  radio.openReadingPipe(1,pipes[1]);
  radio.startListening();

  lcd.init(); // initialize the lcd
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("M1=");
  lcd.setCursor(8,0);
  lcd.print("M2=");
  lcd.setCursor(0,1);
  lcd.print("M3=");
  lcd.setCursor(8,1);
  lcd.print("M4=");
  lcd.setCursor(0,2);
  lcd.print("Bat remote = ");
  lcd.setCursor(0,3);
  lcd.print("Bat rover = ");
}

void loop(){
  joystick[0] = analogRead(A0);
  joystick[1] = analogRead(A1);
  joystick[2] = roverState;

  batr = analogRead(A3) / 102.3;

  if ( bouncerz.update() ) {
    if ( bouncerz.read() == LOW) {
      if ( roverState == HIGH ) {
        roverState = LOW;
      } 
      else {
        roverState = HIGH;
      }
    }
  }

  joystick[3] = digitalRead(clawopen);    
  joystick[4] = digitalRead(clawclose);


  if ( radio.available() )
  {
    unsigned long roverMillis = millis();

    if(roverMillis - previousMillis &gt; interval) {
      previousMillis = roverMillis;   

      // Dump the payloads until we've gotten everything
      bool done = false;
      while (!done)
      {
        // Fetch the payload, and see if this was the last one.
        done = radio.read( &amp;rover, sizeof(rover) );

      }
    }

    radio.stopListening();

    bool ok = radio.write( &amp;joystick, sizeof(joystick) );

    radio.startListening();  

  }
  lcd.setCursor(3,0);
  lcd.print(rover[0]);
  lcd.setCursor(11,0);
  lcd.print(rover[1]);
  lcd.setCursor(3,1);
  lcd.print(rover[2]);
  lcd.setCursor(11,1);
  lcd.print(rover[3]);
  lcd.setCursor(13,2);
  lcd.print(batr);
  lcd.setCursor(12,3);
  lcd.print(rover[4]);
}

The sketch that went into the Mega1280 based micro controller on the Rover 5:

// http://www.bajdi.com
// Dagu Rover 5 chassis with 4 motors and 3 DOF gripper
// Remote control through Nrf24L01 2,4GHz wireless module
// µcontroller = Dagu Red back spider, Arduino Mega 1280 compatible
// Motor controller = Dagu 4 channel motor controller

#include &lt;SPI.h&gt;
#include &lt;nRF24L01.h&gt;
#include "RF24.h"
#include "Ultrasonic.h"
#include &lt;Servo.h&gt;

Servo bottomservo;  // create servo object to control a servo
Servo shouldservo;  // create servo object to control a servo
Servo clawservo;  // create servo object to control a servo

/* Nrf24L01 pinout
 1 GND
 2 VCC (3,3V)
 3 CE    pin 48 on Mega 1280
 4 CSN   pin 49 on Mega 1280
 5 SCK   pin 52 on Mega 1280
 6 MOSI  pin 51 on Mega 1280
 7 MISO  pin 50 on Mega 1280
 8 IRQ (not used)
 */

RF24 radio(48,49);
const uint64_t pipes[2] = { 
  0xF0F0F0F0E1LL, 0xF0F0F0F0D2LL };

const int DirM1 = 30; // direction motor 1
const int DirM2 = 31; // direction motor 2
const int DirM3 = 32; // direction motor 3
const int DirM4 = 33; // direction motor 4
const int PWMM1 = 4;  // pwm motor 1
const int PWMM2 = 5;  // pwm motor 2
const int PWMM3 = 6;  // pwm motor 3
const int PWMM4 = 7;  // pwm motor 4

uint8_t fs; // forward speed
uint8_t bs; // backward speed
uint8_t ls; // turn left speed
uint8_t rs; // turn right speed

int bat; // analog reading of battery voltage through voltage divider
const int lowbat = 34; // low battery led (red)
const int buzzer = 35; // buzzer
const int orange = 38; // orange leds
const int headlight = 39; // white leds

const int  TRIG = 36;
const int  ECHO = 37;

uint8_t XNewPos =  110;
uint8_t YNewPos =  146;
uint8_t ZNewPos =  100;

int Xcounter = 0;
int Ycounter = 0;
int Zcounter = 0;

int XOldPos;
int YOldPos;
int ZOldPos;

long previousMillis1 = 0;
long previousMillis2 = 0;
long previousMillis3 = 0;

const int intervalg = 50;

Ultrasonic SRF6A(TRIG, ECHO);

int joystick[5];    // Array with 2 analog values (X,Y-axis) and one digital (Z-axis) from transmitter/joystick
float rover[5];   // Array with the 4 motor rover values, to sent to remote control

int apin[] = { 
  A1, A2, A3, A4 };  // analog pin array

long previousMillis = 0;

const int interval = 100;

void setup() {
  pinMode(DirM1, OUTPUT);  // direction motor 1, left front
  pinMode(DirM2, OUTPUT);  // direction motor 2, left rear
  pinMode(DirM3, OUTPUT);  // direction motor 3, right front
  pinMode(DirM4, OUTPUT);  // direction motor 4, right rear
  pinMode(PWMM1, OUTPUT);  // PWM motor 1
  pinMode(PWMM2, OUTPUT);  // PWM motor 2
  pinMode(PWMM3, OUTPUT);  // PWM motor 3
  pinMode(PWMM4, OUTPUT);  // PWM motor 4
  pinMode(lowbat, OUTPUT); // low battery led (red)
  pinMode(buzzer, OUTPUT); // buzzer
  pinMode(orange, OUTPUT); // orange leds
  pinMode(headlight, OUTPUT); // white leds

  radio.begin();
  radio.openWritingPipe(pipes[1]);
  radio.openReadingPipe(1,pipes[0]);
  radio.startListening();
  
  bottomservo.attach(9);     // attaches the servo on pin 9 to the servo object 
  shouldservo.attach(10);   // attaches the servo on pin 10 to the servo object
  clawservo.attach(11);   // attaches the servo on pin 11 to the servo object
}

void loop() {

  rover[4] = analogRead(A0) /102.3;

  if ( radio.available() )
  {
    // Dump the payloads until we've gotten everything
    bool done = false;
    while (!done)
    {
      // Fetch the payload, and see if this was the last one.
      done = radio.read( &amp;joystick, sizeof(joystick) );
    }
    if (rover[4] &gt; 7.4)
    {
      if(joystick[2] == LOW)       // 760 / 1023 * 5 * 2 = 7,4V from battery  
      {

        digitalWrite(headlight, HIGH); // turn on headlights

        if(SRF6A.Ranging(CM) &lt; 5){
          digitalWrite(buzzer, HIGH);      // we're going to crash 
        }
        else {
          digitalWrite(buzzer, LOW); 
        } 

        if (joystick[0] &gt; 490 &amp;&amp; joystick[0] &lt; 510 &amp;&amp; joystick[1] &gt; 490 &amp;&amp; joystick[1] &lt; 510 )    // joystick is centered
        {
          stopped();
        }

        if (joystick[1] &gt;= 505 &amp;&amp; joystick[0] &gt; 490 &amp;&amp; joystick[0] &lt; 510)               // joystick forward = all motors forward
        {
          bs = (map(joystick[1], 510, 1023, 30, 250));
          backward(bs);
        }

        if (joystick[1] &lt;= 490 &amp;&amp; joystick[0] &gt; 490 &amp;&amp; joystick[0] &lt; 510)               // joystick backward = all motors backward
        {
          fs = (map(joystick[1], 490, 0, 30, 250));
          forward(fs);
        }

        if (joystick[0] &lt;= 490 &amp;&amp; joystick[1] &gt; 490 &amp;&amp; joystick[1] &lt; 510)              // joystick left = left motors backward &amp;&amp; right motors forward
        {
          rs = (map(joystick[0], 490, 0, 30, 250));
          turnright(rs);
        }

        if (joystick[0] &gt;= 510 &amp;&amp; joystick[1] &gt; 490 &amp;&amp; joystick[1] &lt; 510)              // joystick right = left motors forward &amp;&amp; right motors backward
        {
          ls = (map(joystick[0], 510, 1023, 30, 250));
          turnleft(ls);
        }
      }
      else {
        stopped();
        digitalWrite(headlight, LOW); // turn off headlights
        digitalWrite(orange, HIGH);

        if ( joystick[3] == LOW &amp;&amp; ZNewPos &lt; 169)
        {
          Zcounter+=2;
          ZNewPos = ZNewPos + Zcounter;
        }

        if ( joystick[4] == LOW &amp;&amp; ZNewPos &gt; 92)
        {
          Zcounter+=2;
          ZNewPos = ZNewPos - Zcounter;
        }

        if (joystick[0] &gt; 600 &amp;&amp; XNewPos &lt; 180)
        {
          Xcounter+=3;
          XNewPos = XNewPos + (Xcounter);
        }

        if (joystick[0] &lt; 400 &amp;&amp; XNewPos &gt; 30)
        {
          Xcounter+=3;
          XNewPos = XNewPos - (Xcounter);
        }

        if (joystick[1] &lt; 400 &amp;&amp; YNewPos &lt; 174)
        {
          Ycounter+=3;
          YNewPos = YNewPos + (Ycounter);
        }

        if (joystick[1] &gt; 600 &amp;&amp; YNewPos &gt; 50)
        {
          Ycounter+=3;
          YNewPos = YNewPos - (Ycounter);
        }

        unsigned long currentMillis1 = millis();

        if(XOldPos != XNewPos &amp;&amp; currentMillis1 - previousMillis1 &gt; intervalg) {	 
          previousMillis1 = currentMillis1;
          Xcounter = 0;
          XOldPos = XNewPos;
          if(XNewPos &lt; 30)
          {
            XNewPos = 30;
          }
          if(XNewPos &gt; 180)
          {
            XNewPos = 180;
          }
          bottomservo.write(XNewPos);     // tell servo to go to position in variable 'XNewPos'
        } 

        unsigned long currentMillis2 = millis();

        if(YOldPos != YNewPos &amp;&amp; currentMillis2 - previousMillis2 &gt; intervalg) {
          previousMillis2 = currentMillis2;
          Ycounter = 0;
          YOldPos = YNewPos;
          if(YNewPos &lt; 50)
          {
            YNewPos = 50;
          }
          if(YNewPos &gt; 174)
          {
            YNewPos = 174;
          }
          shouldservo.write(YNewPos);     // tell servo to go to position in variable 'YNewPos' 
        }

        unsigned long currentMillis3 = millis();

        if(ZOldPos != ZNewPos &amp;&amp; currentMillis3 - previousMillis3 &gt; intervalg) {	    // Issue command only if desired position changes
          previousMillis3 = currentMillis3;
          Zcounter = 0;
          ZOldPos = ZNewPos;

          // Set servo in degrees from approximately 0 to 180
          if(ZNewPos &lt; 92)
          {
            ZNewPos = 92;
          }
          if(ZNewPos &gt; 169)
          {
            ZNewPos = 169;
          }
          clawservo.write(ZNewPos);     // tell servo to go to position in variable 'ZNewPos' 
        }
      }
    }
  }

  unsigned long roverMillis = millis();
  if(roverMillis - previousMillis &gt; interval) {
    previousMillis = roverMillis;   

    radio.stopListening();
    bool ok = radio.write( &amp;rover, sizeof(rover) );
    radio.startListening();
  }
  // 4 analog readings from motor controller = motor rover
  for (int i=0; i&lt;4; i++)
  {
    rover[i] = analogRead( apin[i] )/ 1023.0 * 5.0;
  }
}

void stopped()
{
  analogWrite(PWMM1, 0);
  analogWrite(PWMM2, 0);
  analogWrite(PWMM3, 0);
  analogWrite(PWMM4, 0);
  digitalWrite(orange, LOW);
}

void forward(int fs)
{
  digitalWrite(DirM1, HIGH);
  digitalWrite(DirM2, HIGH);
  digitalWrite(DirM3, HIGH);
  digitalWrite(DirM4, HIGH);
  analogWrite(PWMM1, fs);
  analogWrite(PWMM2, fs);
  analogWrite(PWMM3, fs);
  analogWrite(PWMM4, fs);
  digitalWrite(orange, LOW);
}

void backward(int bs)
{
  digitalWrite(DirM1, LOW);
  digitalWrite(DirM2, LOW);
  digitalWrite(DirM3, LOW);
  digitalWrite(DirM4, LOW);
  analogWrite(PWMM1, bs);
  analogWrite(PWMM2, bs);
  analogWrite(PWMM3, bs);
  analogWrite(PWMM4, bs);
  digitalWrite(orange, LOW);
}

void turnleft(int ls)
{
  digitalWrite(DirM1, LOW);
  digitalWrite(DirM2, LOW);
  digitalWrite(DirM3, HIGH);
  digitalWrite(DirM4, HIGH);
  analogWrite(PWMM1, ls);
  analogWrite(PWMM2, ls);
  analogWrite(PWMM3, ls);
  analogWrite(PWMM4, ls);
  digitalWrite(orange, HIGH);
}

void turnright(int rs)
{
  digitalWrite(DirM1, HIGH);
  digitalWrite(DirM2, HIGH);
  digitalWrite(DirM3, LOW);
  digitalWrite(DirM4, LOW);
  analogWrite(PWMM1, rs);
  analogWrite(PWMM2, rs);
  analogWrite(PWMM3, rs);
  analogWrite(PWMM4, rs);
  digitalWrite(orange, HIGH);
}

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