TPA81 Thermopile Array and NXT

[quantgeek]

Hi,

I got this sensor that I want to use with my NXT. Does anyone know how to connect this to the NXT? It is an I2C 5V sensor. The specs are available here:

http://www.robot-electronics.co.uk/htm/tpa81tech.htm

There seems to be some members who appears to have connected it...

Thanks,

QuantGeek

[TechnoX]

I have done it for RoboCup! Works like a charm!

You have to add external resistors for clock and data lines. I did a small adapter with a NXT female connector and a female header.

What specifically do you wonder? I can upload some code and images in the weekend if you want

[quantgeek]

Technox,

Yes!!! Images and sample code would be great. Since I am not an engineer, connection tips would be wonderful! Where you able to use the SERVO output as well??

Thanks,

Quant Geek

[TechnoX]

We didn't used the servo output, I haven't read so much about it. But with my code you are able to read the individual segments and then act according to that, I think it's easier for the NXT to do so instead of reading PWM signals(?).

I'll try to find my images (or take new ones) tomorrow

This is the class I used. Hope it works for you!

Code: Select all

import lejos.nxt.*;

/**
 * Class to read of the heat sensor
 *
 * @author SOFT Robotics
 * @author Fredrik Löfgren
 * @author Sebastian Gustafsson
 * */
public class HeatSensor extends I2CSensor {

   static final byte ADDRESS = (byte) 0xD0;

    // Data buffer for the IR values
   private byte[] data = new byte[1];

   public HeatSensor(I2CPort port, byte adress) {
      super(port, adress, I2CPort.STANDARD_MODE, I2CSensor.TYPE_LOWSPEED);
   }

   public HeatSensor(I2CPort port) {
      this(port, ADDRESS);
   }

   public void testSensor() {
      int ret;

      if ((ret = this.getData(0, data, 1)) < 0)// Can fetch data?
         throw new RuntimeException("Heatr: " + ret);
      else if (data[0] <= 0) // Correct data returned?
         throw new RuntimeException("Heatd: " + data[0]);
   }

   /** Return the most heated segment that the sensor sees just now */
   public int getHeat() {
      int max = 0;
      for (int pos = 0; pos < 8; pos++) {
         this.getData(pos + 0x02, data, 1); // read pixel command
         if (data[0] > max)
            max = data[0] & 0xFF;
      }
      return max;
   }

   /** Read internal temperature */
   public byte ReadAmbient() {
      this.getData(0x01, data, 1); // the i2c read command
      return data[0];
   }

   /** Read one pixel */
   public byte ReadPixel(int pos) {
      this.getData(pos + 0x02, data, 1); // read pixel command
      return data[0];
   }
}


[warrocket94]

Hi
i'm an italian student and i use TPA-81 with my Lego Mindstorm NXT 2.0... but it's so difficoult to programme it... the hardware parts is finished but now i'm programming it...on the web i don't find some programme to help me... is there that can help me to programme TPA 81 Sensor? I use bricx command center to programme the sensor..

Thank you very much for your help

Davide

[TechnoX]

What have you tried?

I would use the ReadI2CRegister method.

[warrocket94]

I use this string to read the value of the temperature of the TPA but it's wrong because the LCD Lego Display always show me this value "-32".
http://bricxcc.sourceforge.net/nbc/nxcd ... 6b5b92d77d


This is the programme that i try:

int temp,port,address;
byte outbuffer [8];

task main()
{
port=1; //it's the number of port where i connect the TPA81 on the Lego Brick
address=208; //it's the 0xD0 adress in decimal value
do
{
temp = I2CRead(port, address, outbuffer);
TextOut(5,LCD_LINE2,"temp");
Wait(1000)
}
while (1)
}


this programme don't work because the LCD Lego Display shows only this value "-32"

Can you help me pleaseeee!! i don't find something on the web that can help me. Should you help me please?

[TechnoX]

I have not been programming NXC for several years, and I think this is the wrong place to get good answers about it...

But the TPA81 uses registers, so you need to specify from what register you want to read. Either by doing a write before you read values from the sensor, or by using the function (ReadI2CRegister) I recomended earlier. The last method is easier and clearer.

Code: Select all

int temp,port,address;
byte outbuffer [1];

task main()
{
port=1; //it's the number of port where i connect the TPA81 on the Lego Brick
address=208; //it's the 0xD0 adress in decimal value
do
{
temp = ReadI2CRegister(port, address, 2, outbuffer); // Just read the first segment
NumOut(5, LCD_LINE2, temp);
Wait(1000)
}
while (1)
}


I have not tested the code above, but I think you get the idea?

[warrocket94]

yes i try the "I2C Read Register" but the LCD Lego Display show me this value : "-32"... "-32" is an error and it means that 0xE0 (the specific channel or connection) is not configured or busy. And i don't know how i can resolve this problem!
http://bricxcc.sourceforge.net/nbc/nxcd ... 4e7fd3d94d
In the link there are some parametres that i don't know very well... For example what are "reg" and "out" parametres? And what are their value?
Moreover need i activate the sensor with some string?

[gloomyandy]

Hi,
You will probably get more help with your NXC questions over on the mindboards forum...
http://sourceforge.net/apps/phpbb/mindb ... 05fa829bc5
That is where most of the NXC users tend to hang out...

Andy