Blutack

In dedication to one of the most useful things in my room…Blutack

Oh blutack, why art though so awesome? You gotta love these things, they help people like me who’s lousy in fabrication. This post is dedicated to you, since you helped create it.

Pan and tilt system using two servos and the yaw and pitch axes

That’s right! This is just an upgrade to my last video. This time I’m using two servos and utilising two axes(axii?). As I’ve said above this video is dedicated to the almighty blutack, and you’ll understand what I mean when you see the photos below. I was meaning to post earlier but just got off work a couple of hours ago, I just wanted to do something rough before I hit the hay as the goddess of luck and robotics smiled upon me when I asked Ted if he has another servo. I’ve been itching to do this for a while now, and the itch has been cured…for now! Again this is very rough work, this is probably the first time you’ll ever see such a thing as a cardboard bracket with blutack hinges. But I plan to upgrade with sugru soon, if I manage to get my hands with some more of them. Anyway without further ado, Blue the blutack jointed robot(ps please watch videos in 720p or 1080p as it looks horrible on 480p):

20121107-003723.jpg

20121107-003752.jpg


//
// This program interfaces a Wii wii motion plus with the dsPIC using the I2C module
// Pan and tilt using two servos
// Program written by Gian Lorenzo
// Last edited 07/11/2012 1:39AM
//

#include <libpic30.h>
#include <p30f4011.h>
#include <stdio.h>
#include <xc.h>
#include <i2c.h>
#include <math.h>

// Configuration settings
_FOSC(CSW_FSCM_OFF & FRC_PLL16);  // Fosc=16x7.5MHz, Fcy=30MHz
_FWDT(WDT_OFF);                   // Watchdog timer off
_FBORPOR(MCLR_DIS);               // Disable reset pin

// Function prototypes
void setup();								// Configure pins etc
unsigned int read_analog_channel(int n);	// Reading analog channel
void wiimp_init();						// wiimp initialisation/Handshake
void calibrate();
void wiimp_read(unsigned char*);			// Reading data from the Wii wiimp              // Nunchuk data array
void pause(unsigned int ms);				// Pause function(in ms)
void forward();								// Moves the Servo forward
void back();								// Moves the Servo backward

double yawzero=8054.7,pitchzero=7744,rollzero=7745,
yaw,roll,pitch, deltayaw, deltaroll,deltapitch;
unsigned char  wii_data[20],c; 


int main()
{
	unsigned int ax,ay,az;  // Data containers
	setup();				// Set up which pins are which and set up i2c and configs
	pause(1000);			// 1 second startup delay
	wiimp_init();			// Initialise wii motio plus
	pause(1000);
	//calibrate();			// Calibrate for 0
	pause(1000);
	int o = 0;
	
	while(1)
	{
		if(o == 0)	// Get rid of bad readings
		{
			wiimp_read(wii_data);                      
			wiimp_read(wii_data);
			wiimp_read(wii_data);
			wiimp_read(wii_data);
			wiimp_read(wii_data);
			wiimp_read(wii_data);
			wiimp_read(wii_data);
			pause(2000);
			o++;
		}
				
		wiimp_read(wii_data);                       // Read data from nunchuk

		ax = ((wii_data[3] & 0xFC) << 6) + wii_data[0];	// Extract gyroscope yaw byte
		ay = ((wii_data[4] & 0xFC) << 6) + wii_data[1];	// Extract gyroscope roll byte
		az = ((wii_data[5] & 0xFC) << 6) + wii_data[2];	// Extract gyroscope pitch byte
		
		yaw = ax - yawzero;
		roll = ay - rollzero;
		pitch = az - pitchzero;
		
		deltayaw = deltayaw + yaw;
		deltaroll = deltaroll + roll;
		deltapitch = deltapitch + pitch;
		
		
		if (U2STAbits.URXDA == 1)			//recalibration using uart
		{
			c = U2RXREG;
			if (c == 'y')	deltayaw = 0;
			else if(c == 'p')	deltapitch =0;
			else if(c =='r')	deltaroll =0;
			else if(c == 'a')	deltayaw =0;deltapitch=0;deltaroll=0;
		}
		PDC2 = 1410+(deltapitch*0.06083333333333/2);
		PDC1 = 1280-(deltayaw*.06083333333333/2);
		pause(20);
		//printf("%1d\r %1d\r %1d\r\r\n", ax, ay, az);
		printf("%1f\r %1f\r %1f\r\r\n", deltayaw, deltaroll, deltapitch);
	}

    return 0;
}
void forward()
{
	if(PDC1 < 2010)
	{
		PDC1 = PDC1 + 20;
		pause(.5);
	}
}
void back()
{
	if(PDC1 > 550)
	{
		PDC1 = PDC1 - 20;
		pause(.5);
	}
}

void setup()
{
    // Setup UART
	__C30_UART=2;			// Use secondary UART
    U2BRG = 48;            	// 38400 baud @ 30 MIPS
    U2MODEbits.UARTEN = 1; 	// Enable UART

    // Configure D ports as a digital outputs
    LATD = 0;
    TRISD = 0b11110000;

    // Configure analog inputs
    TRISB = 0x01FF;      /* Port B all inputs */
    ADPCFG = 0xFF00;     /* PORTB 0-7 are analog inputs */
    ADCON1 = 0;          /* Manually clear SAMP to end sampling, start conversion*/
    ADCON2 = 0;          /* Voltage reference from AVDD and AVSS */
    ADCON3 = 0x0005;     /* Manual Sample, ADCS=5 -> Tad = 3*Tcy = 0.1us */
    ADCON1bits.ADON = 1; /* Turn ADC ON */

    // Configure PWM
    // PWM period = Tcy * prescale * PTPER = 0.33ns * 64 * 9470 = 20ms
    PWMCON1 = 0x00FF; // Enable all PWM pairs in complementary mode
    PTCON = 0;
    _PTCKPS = 3;      // prescale=1:64 (0=1:1, 1=1:4, 2=1:16, 3=1:64)
    PTPER = 9470;     // 20ms PWM period (15-bit period value)
    PDC1 = 0;         // 0% duty cycle on channel 1 (max is 65536)
    PDC2 = 0;         // 0% duty cycle on channel 2 (max is 65536)
    PDC3 = 0;         // 0% duty cycle on channel 3 (max is 65536)
    PTMR = 0;         // Clear 15-bit PWM timer counter
    _PTEN = 1;        // Enable PWM time base
	
	// Configure I2c
	I2CCONbits.I2CSIDL = 1;	// Stop module in idle mode
	I2CCONbits.A10M = 0;	// 7-bit address
	I2CCONbits.DISSLW = 0;	// slew rate control. Required to be on for 400kHZ
	I2CBRG = 272;			// 272 for 100kHz at FCY = 30MHz formula next line
							// I2CBRG = (((1/rate)-900ns)*FCY)-1
	I2CCONbits.I2CEN = 1;	// Enable i2c
}

void calibrate()
{
	int i=0,o=0;
    for (o=0;o<10;o++)
      {
        wiimp_read(wii_data);
		pause(10);
      }
	wiimp_read(wii_data);
    yawzero=((wii_data[3]>>6)+wii_data[0]);
    rollzero=((wii_data[4]>>6)+wii_data[1]);
    pitchzero=((wii_data[5]>>6)+wii_data[2]);
    for (i=0;i<10;i++)
      {
        wiimp_read(wii_data);
        yawzero=((wii_data[3]>>6)+wii_data[0])+yawzero/2; //average 10 readings
        rollzero=((wii_data[4]>>6)+wii_data[1])+rollzero/2;
        pitchzero=((wii_data[5]>>6)+wii_data[2])+rollzero/2;
      }
	printf("%f %f %f", yawzero,rollzero,pitchzero);
	pause(2000);
}
void wiimp_init(void) 
{
	StartI2C();			// Open I2C bus
	IdleI2C();			// Wait for last command to finish
	MasterWriteI2C(0xA6);// Call device adress 53(Wii wiimp)
	MasterWriteI2C(0xFE);// Handshake protocol for wii wiimp	
	MasterWriteI2C(0x04);
	StopI2C();
	printf("connected\r\n");
}

void wiimp_read(unsigned char* array) 
{
	int idx;	// Counter

	// ---- Request measurement ---- //
	StartI2C();		// Open I2C bus
	IdleI2C();		// Wait for last command to finish
	MasterWriteI2C(0xA4); // Call the adress you want to read from
	MasterWriteI2C(0x00);	
	StopI2C();		// Stop I2C
	pause(10); 	// 3 ms or more required or acquisition goes wrong

	 //Request reading
  	StartI2C();	// Open I2C bus
	IdleI2C();	// Wait for last command to finish
	MasterWriteI2C(0xA5);	// 0XA5 is the read adress of the wii wiimp(52+1)
	IdleI2C();	// Wait for last command to finish
	 //Bytes reception
	for(idx = 0; idx < 5; idx++)
	{
		array[idx] = MasterReadI2C(); 	// Store the values into an array
		AckI2C(); 						// Send an ACK to notify wiimp to send next byte
		IdleI2C();						// Wait for last command to finish
	}
	pause(1);
	array[5] = MasterReadI2C(); 		// Last byte to be read
	NotAckI2C(); IdleI2C();				// Send a NACK to tell wiimp that reading is done
	StopI2C();							// Stop I2C
}

// Analogue input reading
unsigned int read_analog_channel(int channel)
{
    ADCHS = channel;          // Select the requested channel
    ADCON1bits.SAMP = 1;      // start sampling
    __delay32(30);            // 1us delay @ 30 MIPS
    ADCON1bits.SAMP = 0;      // start Converting
    while (!ADCON1bits.DONE); // Should take 12 * Tad = 1.2us
    return ADCBUF0;
}
void pause(unsigned int ms)
{
	__delay32(30000L*ms);	// 1ms Pause = (ms * FCY/1000)
}
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2 comments on “Blutack

  1. batchloaf says:

    Seriously Gian, that video is awesome. It’s just eerie how faithfully it tracks your movements!

    • Gian Lorenzo says:

      I’m trying to set it up in the hallway now, longer leads. Waiting for someone to go to the toilet 🙂 I need a new hobby haha. Updating my code now, forgot the recalibration using uart.

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