Thread Like Operation in Javelin Multi Sensor Acquistion

dkwon

Hello

I am using several sensors such as two compasses, two accelerometers, force sensors, etc.

Each sensor acquistion module is designed as class. When I get the data, the speed is quite slower.
Do I have to use VP or Timer or Task things?

Would you give me the best way to handle Thread like operation for javelin sensor acquistion?

I am doing like this.

Accel accel1 = new Accel();
Accel accel2 = new Accel();
Compass cmps1 = new Compass();
Compass cmps2 = new Compass();

while(true)
{
· accel1.getData();
· accel2.getData();
· cmps1.getData();
· cmps2.getData();
}

Best Regards,

Doo Young Kwon

Peter Verkaik

You already have the fastest while loop, so if things are slow,

the problem is within the classes themselves.

Can you post these classes?

regards peter

dkwon

Hello Peter

Here is my code. You will notice that I am sending the data using "sendByte" function without using shift. So they do not work properly. I am working on that following your comment in another post. The main question was asking whehter i should install VP or timer for each acquisition class.

In addition, In parallel, I am computing pitch, yaw, roll value using two compass and two accels by attaching perpendiculary. Since I am really beginner regarding Basic Stamp Bit Math, I am still working on it. If you have a good source, it will be enormous help for me.

Thanks alot.

//////////////////////////////////////
// ACSensor.java (main)
//////////////////////////////////////

/**
*
*
* Sensor:
* Two two-axis accelerometers (Memsic2125)
* Two two-axis digital compass (Hm55bCompass)
* <P><U> Pin Arrangement </U> <BR>
*
* Pin 8 (Flat Accelerometer: X-Axis Output) <BR>
* Pin 9 (Flat Accelerometer: Y-Axis Output) <BR>

* Pin 11 (Vertical Acceleromter: X-Axis Output) <BR>
* Pin 12 (Vertical Acceleromter: Y-Axis Output) <BR>
*
* Pin 6 (Flat Magnetometer: to/from Din/Dout) <BR>
* Pin 5 (Flat Magnetometer: Clk) <BR>
* Pin 4 (Flat Magnetometer: EN) <BR>

* Pin 13 (Vertical Magnetometer: to/from Din/Dout) <BR>
* Pin 5 (Vertical Magnetometer: Clk) <BR>
* Pin 4 (Vertical Magnetometer: EN) <BR>

* @version - 1.00 Initial test file
* @author - Doo Young Kwon
*/

import stamp.core.*;
import stamp.peripheral.mems.Accel;
import stamp.peripheral.mems.Compass;

public class ACSensor
{
final static int txpin = CPU.pin0;
static Uart txUart = new Uart(Uart.dirTransmit,txpin,Uart.dontInvert,Uart.speed9600,Uart.stop1);

static int[noparse]/noparse bufsend = new int[noparse][[/noparse]7];
static int index = 0;

public static void main()
{
Accel faccel = new Accel(8, 9); // x pin, y pin
Accel vaccel = new Accel(11, 12);
Compass fcmps = new Compass(6, 5, 4); // dbinout pin, clk pin, en pin
Compass vcmps = new Compass(13, 5, 4);

while(true)
{
bufsend[noparse][[/noparse]0] = faccel.getAccelX(); // x - axis
bufsend[noparse][[/noparse]1] = faccel.getAccelY(); // y - axis
bufsend[noparse][[/noparse]2] = vaccel.getAccelX(); // z -axis


fcmps.runCompass();
bufsend[noparse][[/noparse]3] = fcmps.getCompassX(); // x - axis
bufsend[noparse][[/noparse]4] = fcmps.getCompassY(); // y - axis
vcmps.runCompass();
bufsend[noparse][[/noparse]5] = vcmps.getCompassX(); // z -axis

index = 0;
while (index < 6)
{
txUart.sendByte(bufsend[noparse][[/noparse]index++]);
}
}
}
}

//////////////////////////////////////
// Accel.java (Accelerometer class)
//////////////////////////////////////

package stamp.peripheral.mems;
import stamp.core.*;

public class Accel {

private int m_pinX;
private int m_pinY;

private int m_ctime;
private static int m_timeout;

public Accel(int pinX, int pinY)
{
m_timeout = 2000;
m_pinX = CPU.pins[noparse][[/noparse] pinX ];
m_pinY = CPU.pins[noparse][[/noparse] pinY ];
}

private void setCycleTime( )
{
m_ctime = (CPU.pulseIn(m_timeout, m_pinX, true) +
CPU.pulseIn(m_timeout, m_pinX, false)) ;
}

public int getAccelX()
{
return CPU.pulseIn(m_timeout, CPU.pin8, true);
}

public int getAccelY()
{
return CPU.pulseIn(m_timeout, CPU.pin9, true);
}

}

//////////////////////////////////////
// Compass.java (Compass class)
//////////////////////////////////////

package stamp.peripheral.mems;
import stamp.core.*;
import stamp.math.IntegerMath;

public class Compass {

private static int m_DinDout;
private static int m_Clk;
private static int m_En;

private static final int RESET = 0x0000;
private static int m_Measure = 0x0008;
private static int m_Report = 0x000c;
private static final int READY = 0x000c;

private int m_x;
private int m_y;
private int m_status;
private int m_angle;

public Compass(int DinDout, int Clk, int En) {
m_DinDout = CPU.pins[noparse][[/noparse] DinDout ]; ;
m_Clk = CPU.pins[noparse][[/noparse] Clk ];
m_En = CPU.pins[noparse][[/noparse] En ];
}
public int getCompassX()
{
return m_x;
}

public int getCompassY()
{
return m_y;
}

public int getAngle(){

m_angle = IntegerMath.atan2(-m_y, m_x);

return m_angle;
}


public void runCompass(){
CPU.writePin(m_Clk, false);
CPU.writePin(m_En, true);
CPU.writePin(m_En, false);
CPU.shiftOut(m_DinDout, m_Clk, 4, CPU.SHIFT_MSB,RESET);

CPU.writePin(m_En, true);
CPU.writePin(m_En, false);
CPU.shiftOut(m_DinDout, m_Clk, 4, CPU.SHIFT_MSB, m_Measure << 12);

do {
CPU.writePin(m_En, true);
CPU.writePin(m_En, false);
CPU.shiftOut(m_DinDout, m_Clk, 4, CPU.SHIFT_MSB, m_Report << 12);
m_status = CPU.shiftIn(m_DinDout, m_Clk, 4, CPU.POST_CLOCK_MSB );
} while (m_status != READY);

m_x = CPU.shiftIn(m_DinDout, m_Clk, 11, CPU.POST_CLOCK_MSB );
m_y = CPU.shiftIn(m_DinDout, m_Clk, 11, CPU.POST_CLOCK_MSB );

CPU.writePin(m_En, true);

if ((m_x & 0x0400) != 0) m_x |= (short)0xF800;
if ((m_y & 0x0400) != 0) m_y |= (short)0xF800;
}
}

Peter Verkaik

I changed your classes a little.
First, I don't think you can share the compass pins clk and en, because both
compasses must be read out individually. So I changed it so that the compasses
share their datapin but not clk and en pins.

Secondly, I changed the way you store passed pins to constructors.
Instead of using pins[noparse]/noparse I simply store the pins that are now defined in your main
class as constants. Pins[noparse]/noparse may not be initialized (in CPU class) properly when
the constructor is called because it is not known when the CPU class is initialized,
unless you do all variable initialization in your main(), as you did.
No need for that·now, variables are neatly declared outside main() which
gives a better overview I think.

Thirdly, I split up your runCompass method in 3 methods: reset(), start() and poll().
This allows you to start a measurement, then while polling you can do other tasks as
well. In the main·class I read in the accelerometer values while the compasses are
progressing their measurement. This should speed up things·a little.

Let us know the results.

regards peter


Post Edited (Peter Verkaik) : 10/27/2005 8:54:50 AM GMT

Peter Verkaik

I added some printouts to the ide message window.

I use Format.printf() for easy printing.

Format class can be found here:

http://groups.yahoo.com/group/JavelinCode/files/Javelin%20Stamp%20IDE/lib/stamp/util/text/

I also noted you only send the lowbytes from the int array bufsend.

To send all bytes use

int value = bufsend[noparse][[/noparse]index++];

txUart.sendByte(value);

txUart.sendByte(value>>>8);

inside that while loop.

regards peter

Peter Verkaik

I have put in some statistics for your compasses.

It shows how many times you must poll before the compasses have new data.

Ideally it should be 1, then the new data is available after the first poll.

If it is larger than 1, you get an idea of the time it takes for the compasses

to complete their measurement, and thus how much time you have

to perform additional tasks while the compasses are progressing the measurements.

regards peter




Post Edited (Peter Verkaik) : 10/27/2005 9:44:40 AM GMT

dkwon

Thanks Peter,
I will post the testing result soon.