Expected primary-expression before '.' token

Projects Programming
1

I get the above error when I try to compile. The error points to lines 34 and 37.

#include "DFRobot_HuskylensV2.h"
#include "DFMobile.h"
#include "Wire.h"

// Create object
HuskylensV2 huskylens;

DFMobile Robot(4, 5, 7, 6); // Motor control pins for Romeo
int centerThreshold = 50; // Tolerance for steering

void setup() {
  Wire.begin();
  Serial.begin(9600);
  while (!huskylens.begin(Wire)) {
    Serial.println("Begin HUSKYLENS failed!");
    delay(100);
  }
  
 Serial.print("Switching to tracking mode");

  // Switch to Object Tracking mode

  huskylens.switchAlgorithm(ALGORITHM_OBJECT_TRACKING);

}

void loop() {
   // Request results from the sensor

      if (huskylens.available(ALGORITHM_OBJECT_TRACKING)) {
    huskylens.getResult(ALGORITHM_OBJECT_TRACKING);
    
    // Check if object is left, right, or center
    if (Result.xCenter < (160 - centerThreshold))  {
      // Object on left: Turn Left
      Robot.Speed(-150, 150); 
    } else if (Result.xCenter > (160 + centerThreshold)) {
      // Object on right: Turn Right
      Robot.Speed(150, -150);
    } else {
      // Object centered: Move Forward
      Robot.Speed(200, 200);
    }
    }  
   else {
    // No object found: Stop
    Robot.Speed(0, 0);
  }
  
}
2

Use the Tools->Auto Format option in the IDE.

After that, post your code again. Also post the complete set of error messages (in code tags)

3

Looks like the correct expression is result.xCenter instead of Result.xCenter

4

I can't see either result or Result defined.

5

It´s part of the HuskyLens library. See GitHub - HuskyLens/HUSKYLENSArduino · GitHub for reference.

6

I didn't find any result in the librsry that would be used that way.

I haven't time to go look again, but came back with this form one of the examlkes

void loop() {
  while (!huskylens.getResult(ALGORITHM_OBJECT_CLASSIFICATION)) {
    delay(100);
  }

  while (huskylens.available(ALGORITHM_OBJECT_CLASSIFICATION)) {
    Result *result = huskylens.popCachedResult(ALGORITHM_OBJECT_CLASSIFICATION);
    Serial.print("result->name=");
    Serial.println(result->name);
    Serial.print("result->classID=");
    Serial.println(result->classID);
    Serial.println();
  }
  delay(1000);
}

in which we see a result being initialised

Result *result = huskylens.popCachedResult(ALGORITHM_OBJECT_CLASSIFICATION);

The code goes on using the '->' notation.

a7

7

Which lines are 34 and 37?

8 
#include "DFRobot_HuskylensV2.h"
#include "DFMobile.h"
#include "Wire.h"

// Create object
HuskylensV2 huskylens;

DFMobile Robot(4, 5, 7, 6);  // Motor control pins for Romeo
int centerThreshold = 50;    // Tolerance for steering

void setup() {
  Wire.begin();
  Serial.begin(9600);
  while (!huskylens.begin(Wire)) {
    Serial.println("Begin HUSKYLENS failed!");
    delay(100);
  }

  Serial.print("Switching to tracking mode");

  // Switch to Object Tracking mode

  huskylens.switchAlgorithm(ALGORITHM_OBJECT_TRACKING);
}

void loop() {
  // Request results from the sensor

  if (huskylens.available(ALGORITHM_OBJECT_TRACKING)) {
    huskylens.getResult(ALGORITHM_OBJECT_TRACKING);

    // Check if object is left, right, or center
    if (Result.xCenter < (160 - centerThreshold)) {
      // Object on left: Turn Left
      Robot.Speed(-150, 150);
    } else if (Result.xCenter > (160 + centerThreshold)) {
      // Object on right: Turn Right
      Robot.Speed(150, -150);
    } else {
      // Object centered: Move Forward
      Robot.Speed(200, 200);
    }
  } else {
    // No object found: Stop
    Robot.Speed(0, 0);
  }
}

Errors:

C:\Projects\Book - 4 - Robots\Devastator Robot\sketch_apr10a\sketch_apr10a.ino: In function 'void loop()':
C:\Projects\Book - 4 - Robots\Devastator Robot\sketch_apr10a\sketch_apr10a.ino:33:15: error: expected primary-expression before '.' token
     if (Result.xCenter < (160 - centerThreshold)) {
               ^
C:\Projects\Book - 4 - Robots\Devastator Robot\sketch_apr10a\sketch_apr10a.ino:36:22: error: expected primary-expression before '.' token
     } else if (Result.xCenter > (160 + centerThreshold)) {
                      ^
exit status 1

Compilation error: expected primary-expression before '.' token
9

Nowhere in your code do you declare any object called Result.

10

I don't have that hardware and I never used that library, but based on the examples, I think you just need to change your loop as follows:

  // Request results from the sensor
  if (huskylens.available(ALGORITHM_OBJECT_TRACKING)) {
    huskylens.getResult(ALGORITHM_OBJECT_TRACKING);
    Result *result = huskylens.popCachedResult(ALGORITHM_OBJECT_CLASSIFICATION);
    // Check if object is left, right, or center
    if (result->xCenter < (160 - centerThreshold))  {
      // Object on left: Turn Left
      Robot.Speed(-150, 150); 
    } else if (result->xCenter > (160 + centerThreshold)) {
      // Object on right: Turn Right
      Robot.Speed(150, -150);
    } else {
      // Object centered: Move Forward
      Robot.Speed(200, 200);
    }
    }  
   else {
    // No object found: Stop
    Robot.Speed(0, 0);
  }

Give it a try.

11

@docdoc might have just added that the only substantial change to the loop is to create and initialize the previously missing variable result, viz:

Result *result = huskylens.popCachedResult(ALGORITHM_OBJECT_CLASSIFICATION);

and go on to use it, rather than Result subsequently.

Since result is a pointer, the '->' is appropriate.

@williampretty where did you find the code that informed your version? It looks like more than a closing brace was missing.

a7

12

I added the closing brace and now I am having troubles with dfmobile.h

I found the code via google. It was supposed to be example code.

13

Here is the Latest error after @docdoc's code.

C:\Users\Bill\AppData\Local\Temp\cc1hdOUN.ltrans0.ltrans.o: In function global constructors keyed to 65535_0_sketch_apr10a.ino.cpp.o.2812': <artificial>:(.text.startup+0xbe): undefined reference to DFMobile::DFMobile(unsigned char, unsigned char, unsigned char, unsigned char)'
C:\Users\Bill\AppData\Local\Temp\cc1hdOUN.ltrans0.ltrans.o: In function loop': C:\Projects\Book - 4 - Robots\Devastator Robot\sketch_apr10a/sketch_apr10a.ino:43: undefined reference to DFMobile::Speed(int, int)'
collect2.exe: error: ld returned 1 exit status
exit status 1

Compilation error: exit status 1

14

Thanks everyone for your help.

I got the software working :smiley:

I have more testing to do. I will share the code once I am done testing.

15

Just out of curiosity, what was causing the error you mentioned in the previous post #12? A library version mismatch?

16

I think so. I found some code that I had written earlier that doesn't use dfmobile.h and it works well so far.

17

Here is what I have so far:

void camera() {

  while (!huskylens.begin(Wire)) {
    Serial.println("Waiting ... ");
    Serial.println("Huskylens not found! Check wiring.");
    delay(100);
  }

  // Switch to Object Tracking mode
  huskylens.switchAlgorithm(ALGORITHM_OBJECT_TRACKING);
  Serial.println("Switching to tracking mode");

  while (true) {
    Serial.println("*");
    // Request results from the sensor
    huskylens.getResult(ALGORITHM_OBJECT_TRACKING);

    if (huskylens.available(ALGORITHM_OBJECT_TRACKING)) {
      Serial.println("Tracking ...");
      // Get the object closest to the center crosshair
      auto target = huskylens.getCachedCenterResult(ALGORITHM_OBJECT_TRACKING);

      // Check if object is left, right, or center
      Serial.print(RET_ITEM_NUM(target, Result, xCenter));

     
      if ( (RET_ITEM_NUM(target, Result, xCenter)) < (160 - centerThreshold)) {
        //Object on left: Turn Left
        turnLeft();

      } else if ((RET_ITEM_NUM(target, Result, xCenter)) > (160 + centerThreshold)) {
        //Object on right: Turn Right
        turnRight();
      }
    }
  }
}

It prints the xCenter coordinate but the vehicle doesn't move.

Switching to tracking mode


*


Tracking ...


152*


Tracking ...


152*
18

That's because a value of 152 fails the condition in each of the following if() statements.

19

Why aren't you checking the return value from that function call? See the library's README:

/**
 * @fn getResult
 * @brief Get recognition results from HuskyLens V2
 * @param algo The algorithm to get results for
 * @return COMMAND_RETURN_ARGS retValue==0 if successful, other values indicate errors
 */
int8_t getResult(eAlgorithm_t algo);
20

@williampretty - please post complete sketch.

The variabke Result is not defined in your snippet.

a7