Transfer code from Mega to Due (Solved)

Projects Programming
1

Hi, I have been using Arduino Mega for a while. Days ago in order to have 64-bit double, I switched to Due. But I found that my old code which works on Mega has error when compiling on Due.

Here's the code:

struct{
  byte len; //ength of message
  byte id; //meassge identification
  unsigned int type; //data type, here type == 2030
  byte data_len; //length of data
  float f_roll;     //value of roll In arduino, float is store in little endian using 4 bytes
  float f_pitch;
  float f_yaw;
  byte cs;  //check sum
} msg; //msg struct for the data stream

  int data[22];  //array used to store the data, including, msg length, id, type, data length, roll, pitch, yaw and cs
  byte * b_roll = (byte *) &msg.f_roll; // pointer for the float value
  byte * b_pitch = (byte *) &msg.f_pitch;
  byte * b_yaw = (byte *) &msg.f_yaw; 
  
  byte old_byte = 0;
  byte new_byte = 0;
  int index = 2;
  int flag = 0;

void serialEvent2(){
}

void setup(){
  Serial.begin(115200);
  Serial2.begin(115200);
  data[0] = 0xFA;
  data[1] = 0xFF;
}

void loop(){
  
  if(Serial2.available()){
    new_byte = Serial2.read();
  if(old_byte == 0xFA && new_byte == 0xFF){
    index = 2;   
    flag = 0;
    }
  else{
    data[index] = new_byte;
    index++;
    }
  if(index > 19){
    flag = 1;
  }
  old_byte = new_byte;
  }
  if(flag == 1){
      b_roll[3] = data[7];
      b_roll[2] = data[8];
      b_roll[1] = data[9];
      b_roll[0] = data[10];
      b_pitch[3] = data[11];
      b_pitch[2] = data[12];
      b_pitch[1] = data[13];
      b_pitch[0] = data[14];
      b_yaw[3] = data[15];
      b_yaw[2] = data[16];
      b_yaw[1] = data[17];
      b_yaw[0] = data[18]; 
       
      Serial.print(msg.f_roll);     
      Serial.print(",");
      Serial.print(msg.f_pitch); 
      Serial.print(",");
      Serial.print(msg.f_yaw);     
      Serial.print("\n");      
  } 
}

It works well on Mega. Basically, it just read data from serial port.
Here's the error message when compiling on Due:

ahars_reading3.ino: In function 'void loop()':
ahars_reading3.ino:37:11: error: assignment of function 'char* index(const char*, int)'
ahars_reading3.ino:37:11: error: cannot convert 'int' to 'char*(const char*, int)' in assignment
ahars_reading3.ino:41:15: error: invalid types 'int [22][char*(const char*, int)]' for array subscript
ahars_reading3.ino:43:10: error: ISO C++ forbids incrementing a pointer of type 'char* (*)(const char*, int)' [-fpermissive]
ahars_reading3.ino:43:10: error: lvalue required as increment operand
ahars_reading3.ino:45:14: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]
Error compiling.

So what's wrong with my code? Is there any other difference when program for Mega and Due?
Thanks in advance.

2

ahars_reading3.ino:37:11: error: assignment of function 'char* index(const char*, int)'

You don't have a function called "index" which takes a char* and an int as arguments, do you? It is defined somewhere else in the Due framework code.

Rename your variable to something else.

3

I don't have function called "index". I switched the variable name into other name and it works now.
I was confused by the error message and didn't expect the problem to be that simple.
Thank you very much.