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Line Following Sensor question

10/12/2007 5:09:24 AM

steve

5 posts

Line Following Sensor question

I am testing your Line Following Sensor.

After 7 reads from my Brainstem controller it seems to stops responding, (always 7)

If I loop 6 or less times, no problem - 7 times and it locks.

void main(){
char result;
aCore_Outportc(aPortIICBaud, 0); /*set bus to slowest speed (std iic)*/

for (y = 1; y <= 6; y++)
{
    result = aI2C_ReadChar((unsigned char)0x50,0);
    aPrint_CharDec(result);
    aPrint_String("\n");
    aCore_Sleep(10000);
};}

Also, If I run the above program for 6 loops and then unplug and plugin the sensor I can run the program again with no lock up. But if I run the program a 2nd time without unpluging then it will lock up the second time on the 1st loop thru the 2nd run (7th overall).

- Different bus speeds
- Tried different I2C cable
- Tried different "Sleep" values (up to 5 seconds between)
- LEDs on sensor still respond even after "lockup"

Any suggestions for a next step?
Steve

10/12/2007 2:10:36 PM

jason

158 posts

Re: Line Following Sensor question

Steve,

I'm not that familiar w/ the BrainStem, but let me read more about it, and understand their I2C interface to help you debug the problem you are seeing.

Is the aI2C_ReadChar() method something you wrote, or is it part of a library associated w/ the BrainStem? If you wrote it, could you post the src code?

Best Regards,

Jason Summerour
President,
Summerour Robotics Corp
Microsoft MVP
www.roboticsconnection.com

10/12/2007 2:28:45 PM

jason

158 posts

Re: Line Following Sensor question

Steve,

You might try:

result = aI2C_ReadChar((unsigned char)0x50,1); // register 1, instead of 0

And see if that alleviates the problem.

We do have several OOPics that we can use to test the Line Follower with. I know that doesn't directly help you, but it would allow us to see if the Line Follower plays well w/ controllers other than the Serializer. :)

Ringo, do you have any ideas?

Jason Summerour
President,
Summerour Robotics Corp
Microsoft MVP
www.roboticsconnection.com

10/13/2007 10:20:29 AM

steve

5 posts

Re: Line Following Sensor question

In answer to your suggestions:
    The aI2C_ReadChar is part of the brainstem's library (I've included it below)
    The register change from 0 to 1 had no effect

I've also:
    changed to a different power supply, just in case.
    changed the port I'm reading, to a voltage sensor on my motor control board, and everything works fine.

Once the sensor locks up after 7 reads, repowering just the sensor gets things going for another 7 reads. Resetting the controller and not the sensor has no effect, the next read it attemps will not work but if I repower the sensor, I get 7 more reads!
Steve

Library Routine:
char aI2C_ReadChar(char addr, char reg)
{
char val=0;
asm
{
   /* write address */
   pushsb    5    /* IIC address       */
   pushlb    1    /* data size         */
   pushsb    6    /* push reg         */
   pushlb    3    /* cmd size          */
   popcmd

   /* read byte from device */
   pushsb    5    /* IIC address       */
   pushlb    1    /* set read bit      */
   orb
   pushlb    1    /* bytes to read     */
   popsm    aPortIICRead
   popbs    1    /* store as char     */
}
return val;
}

jason wrote

Steve,

You might try:

result = aI2C_ReadChar((unsigned char)0x50,1); // register 1, instead of 0

And see if that alleviates the problem.

Ringo, do you have any ideas?

10/13/2007 8:28:01 PM

jason

158 posts