help making accelerometer work with LEDs

system · November 29, 2010, 11:55pm

My lab partner and I are (noobs) trying to get an accelerometer to fade two LEDs from one to the other, and we keep getting closer but we got an error message saying “expected constructor, destructor, or type conversion before ‘(’ token”
can anyone help us out?

{
 /*
  Accelerometer

  A Program which takes input from an accelerometer and outputs the
  data to the serial port

  Hardware:    Parallax MMA7455
  Concept Usage: Games controller
*/

#include <Wire.h>

#define ACCELEROMETER 0x1D //Address for Accelerometer

//REGISTERS
#define MODE_CONTROL  0x16 //Mode control register
#define PULSE_DET     0x1B //Pulse detection threshold limit value
#define X_OUT       0x06 //8 bit register containing value for X
#define Y_OUT       0x07 //8 bit register containing value for Y
#define Z_OUT       0x08 //8 bit register containing value for Z
#define DETECTION     0x0A //Detection source register

//VALUES
#define Z_PULSE     0x40 //Pulse detected on Z-axis
#define SENSEVALUE    0x25 //Default sensitivity level

//tilt def.
 int tilt = 0;
int leftLEDs = 5;
int leftVal = 0;
int rightLEDs = 6;
int rightVal = 0;

pinMode(pwmPin5, OUTPUT);
pinMode(pwmPin6, OUTPUT);

//required setup function
void setup() {
    Wire.begin();
    Serial.begin(9600);
    accWrite(MODE_CONTROL, SENSEVALUE);
}

//required loop function
void loop() {
    Serial.print("X: ");
    Serial.print(accRead(X_OUT), DEC);
    Serial.print("   Y: ");
    Serial.print(accRead(Y_OUT), DEC);
    Serial.print("   Z: ");
    Serial.println(accRead(Z_OUT), DEC);
    delay(100);
    
    {
 // get the tilt data
 if (tilt < 114 ) {
   // process as right tilt
   leftVal = map(tilt, 0,114, 0, 255);
   analogWrite(leftLEDs,leftVal);
   analogWrite(rightLEDs, (leftVal - 255)*-1);
 } else {
   // process as left tilt    //
   rightVal = map(tilt, 114, 228, 0, 255);
   analogWrite(rightLEDs,rightVal);
   analogWrite(leftLEDs, (rightVal - 255)*-1);
 }
}

//function to write byte data into a register
void accWrite(byte address, byte data) {
    Wire.beginTransmission(ACCELEROMETER);
    Wire.send(address);
    Wire.send(data);
    Wire.endTransmission();
}

//function to read byte data from a register
byte accRead(byte address){
    byte val = 0x00;
    Wire.beginTransmission(ACCELEROMETER);
    Wire.send(address);
    Wire.endTransmission();
    Wire.requestFrom(ACCELEROMETER, 1);
    if(Wire.available() > 0) {
      val = Wire.receive();
    }
    Wire.endTransmission();
    return val;
}

// Numbers range in from 46 - 0 and 172 - 255
if(tilt < 50) {
 tilt = tilt + 255;
}
// No matter what tilt is, tilt will read from
// 172 -301
tilt = tilt - 172;
// tilt is 0 - 228
if (tilt <= 114) {
 // tilt right

}else{
 //tilt left


}

CrossRoads · November 30, 2010, 3:39am

You have an extra { at the very start

your pinMode definitions need to be in void setup(), not before you didn't declare the pwmPins prior to setup.

go from there. usually the problem is mismatched {}s, or ()s. Try the AutoFormat before you compile, will tell you basic things like the mismatched number of () & {}.

system · November 30, 2010, 7:47am

Another problem you're going to run into is the value of "tilt", and all the code after "accRead"

system · December 1, 2010, 12:25am

Here’s the re-written code

/*
  Accelerometer

  A Program which takes input from an accelerometer and outputs the
  data to the serial port

  Hardware:    Parallax MMA7455
  Concept Usage: Games controller
*/

#include <Wire.h>

#define ACCELEROMETER 0x1D //Address for Accelerometer

//REGISTERS
#define MODE_CONTROL  0x16 //Mode control register
#define PULSE_DET     0x1B //Pulse detection threshold limit value
#define X_OUT       0x06 //8 bit register containing value for X
#define Y_OUT       0x07 //8 bit register containing value for Y
#define Z_OUT       0x08 //8 bit register containing value for Z
#define DETECTION     0x0A //Detection source register

//VALUES
#define Z_PULSE     0x40 //Pulse detected on Z-axis
#define SENSEVALUE    0x25 //Default sensitivity level

//tilt def.
 int tilt = 0;
int leftLEDs = 5;
int leftVal = 0;
int rightLEDs = 6;
int rightVal = 0;
int pwmPin5 = 5;
int pwmPin6 = 6;



//required setup function
void setup() {
    Wire.begin();
    Serial.begin(9600);
    accWrite(MODE_CONTROL, SENSEVALUE);

pinMode(pwmPin5, OUTPUT);
pinMode(pwmPin6, OUTPUT);
}


//required loop function
void loop() {
    Serial.print("X: ");
    Serial.print(accRead(X_OUT), DEC);
    Serial.print("   Y: ");
    Serial.print(accRead(Y_OUT), DEC);
    Serial.print("   Z: ");
    Serial.println(accRead(Z_OUT), DEC);
    delay(100);
    
}
{
 // get the tilt data
 if (tilt < 114 ) {
   // process as right tilt
   leftVal = map(tilt, 0,114, 0, 255);
   analogWrite(leftLEDs,leftVal);
   analogWrite(rightLEDs, (leftVal - 255)*-1);
 } else {
   // process as left tilt    //
   rightVal = map(tilt, 114, 228, 0, 255);
   analogWrite(rightLEDs,rightVal);
   analogWrite(leftLEDs, (rightVal - 255)*-1);
 }
}

//function to write byte data into a register
void accWrite(byte address, byte data) {
    Wire.beginTransmission(ACCELEROMETER);
    Wire.send(address);
    Wire.send(data);
    Wire.endTransmission();
}

//function to read byte data from a register
byte accRead(byte address){
    byte val = 0x00;
    Wire.beginTransmission(ACCELEROMETER);
    Wire.send(address);
    Wire.endTransmission();
    Wire.requestFrom(ACCELEROMETER, 1);
    if(Wire.available() > 0) {
      val = Wire.receive();
    }
    Wire.endTransmission();
    return val;
}

// Numbers range in from 46 - 0 and 172 - 255
if(tilt < 50) {
 tilt = tilt + 255;
}
// No matter what tilt is, tilt will read from
// 172 -301
tilt = tilt - 172;
// tilt is 0 - 228
if (tilt <= 236) {
 // tilt right
pwmPin5 (OUTPUT,HIGH)
pwmPin6 (OUTPUT,LOW)
}else{
 //tilt left
pwmPin5 (OUTPUT,LOW)
pwmPin6 (OUTPUT,HIGH)
}

we’re still getting an error message, this time saying the same thing but hi-lighting the ‘{’ before “// get the tilt data”

system · December 1, 2010, 7:09am

Yes, that sounds about right. You'll notice the closing brace '}' at the end of 'loop'. That makes the code that follows it outside of a function.

Same goes for

// Numbers range in from 46 - 0 and 172 - 255

Either move it into 'loop', or make it into a new function.

If you're unsure how to structure a program, have a look and work through some of the examples and tutorials.

Consistent indentation helps to follow how a program is structured.

system · December 2, 2010, 12:00am

So we are no longer getting an error message, but when uploaded, the LED in pwmPin5 stays on and the LED in pwmPin6 just dimly flickers. so we’re stumped. any suggestions?

/*

*/

#include <Wire.h>

#define ACCELEROMETER 0x1D //Address for Accelerometer

//REGISTERS
#define MODE_CONTROL  0x16 //Mode control register
#define PULSE_DET     0x1B //Pulse detection threshold limit value
#define X_OUT       0x06 //8 bit register containing value for X
#define Y_OUT       0x07 //8 bit register containing value for Y
#define Z_OUT       0x08 //8 bit register containing value for Z
#define DETECTION     0x0A //Detection source register

//VALUES
#define Z_PULSE     0x40 //Pulse detected on Z-axis
#define SENSEVALUE    0x25 //Default sensitivity level

//tilt def.
int tilt = 0;
int leftLEDs = 5;
int leftVal = 0;
int rightLEDs = 6;
int rightVal = 0;
int pwmPin5 = 5;
int pwmPin6 = 6;

//required setup function
void setup() {
   Wire.begin();
   Serial.begin(9600);
   accWrite(MODE_CONTROL, SENSEVALUE);
   pinMode(pwmPin5, OUTPUT);
   pinMode(pwmPin6, OUTPUT);
}


//required loop function
void loop() {
   Serial.print("X: ");
   Serial.print(accRead(X_OUT), DEC);
   Serial.print("   Y: ");
   Serial.print(accRead(Y_OUT), DEC);
   Serial.print("   Z: ");
   Serial.println(accRead(Z_OUT), DEC);
   delay(100);
   // get the tilt data
   if (tilt < 114 ) {
      // process as right tilt
      leftVal = map(tilt, 0,114, 0, 255);
      analogWrite(leftLEDs,leftVal);
      analogWrite(rightLEDs, (leftVal - 255)*-1);
  } else {
      // process as left tilt    //
      rightVal = map(tilt, 114, 228, 0, 255);
      analogWrite(rightLEDs,rightVal);
      analogWrite(leftLEDs, (rightVal - 255)*-1);
  }
  // Numbers range in from 46 - 0 and 172 - 255
  if(tilt < 50) {
      tilt = tilt + 255;
  }
  // No matter what tilt is, tilt will read from
  // 172 -301
  tilt = tilt - 172;
  // tilt is 0 - 228
  if (tilt <= 236) {
     // tilt right
     analogWrite(5, 255);
     analogWrite(6, 0);
 }else{
     //tilt left
     analogWrite(5, 0);
     analogWrite(6, 255);
 }
}

//function to write byte data into a register
void accWrite(byte address, byte data) {
   Wire.beginTransmission(ACCELEROMETER);
   Wire.send(address);
   Wire.send(data);
   Wire.endTransmission();
}

//function to read byte data from a register
byte accRead(byte address){
   byte val = 0x00;
   Wire.beginTransmission(ACCELEROMETER);
   Wire.send(address);
   Wire.endTransmission();
   Wire.requestFrom(ACCELEROMETER, 1);
   if(Wire.available() > 0) {
     val = Wire.receive();
   }
   Wire.endTransmission();
   return val;
}

system · December 2, 2010, 10:22am

It appears form that code that you know how to use Serial.print() to output debug information. Why don't you output leftVal and rightVal, too? While your at it, why not output tilt, every where that it is set?

Pretty much the root of your problem is right here.

int tilt = 0;

Where does tilt ever get assigned a meaningful value based on the accelerometer readings?

system · May 6, 2021, 8:12pm