Creating a library for arduino

Question

I found a really nice 24 bit I2C adc which was fairly cheap as well (ADS1219) but as far as I could tell there are no libraries for it so I decided to make my own. I have managed to write functions and get everything working on the arduino itself but I've been having massive issues with converting it into a library. So I tried a very basic sketch to see if I can do something as simple as printing hello world using the library. Here is my ADS1219.h file:

#ifndef ADS1219
#define ADS1219

#if ARDUINO >= 100
 #include "Arduino.h"
#else
 #include "WProgram.h"
#endif

class ADS1219{
public:
 ADS1219();
 void begin();
 void printHello();
};

#endif

And the ADS1219.cpp:

#if ARDUINO >= 100
 #include "Arduino.h"
#else
 #include "WProgram.h"
#endif

#include 

ADS1219::ADS1219{
 Serial.println("New object created!");
}

void ADS1219::begin(){
 Serial.begin(9600);
}

void ADS1219::printHello(){
 Serial.println("Hello World");
}

and my main sketch:

#include 

ads = new ADS1219;

void setup() {
  Serial.begin(9600);
  ads.begin();
}

void loop() {
  ads.printHello();
  delay(2000);
}

but I get this really long error which basically says I've failed with creating the ads object. I tried ADS1219 ads; as well but same error ... not sure what's wrong tbh.

Arduino: 1.8.8 (Windows 10), Board: "Arduino Nano, ATmega328P (Old Bootloader)"

In file included from sketchADS1219.cpp:7:0:

ADS1219.h:14:11: error: expected unqualified-id before ')' token

   ADS1219();

           ^

ADS1219.h:12:14: error: an anonymous struct cannot have function members

 class ADS1219{

              ^

ADS1219.h:18:1: error: abstract declarator '' used as declaration

 };

 ^

ADS1219.cpp:9:17: error: expected id-expression before '{' token

 ADS1219::ADS1219{

                 ^

ADS1219.cpp:13:21: error: explicit qualification in declaration of 'void begin()'

 void ADS1219::begin(){

                     ^

ADS1219.cpp:17:26: error: explicit qualification in declaration of 'void printHello()'

 void ADS1219::printHello(){

                          ^

In file included from C:UsersOM222ODesktopadslibadslib.ino:1:0:

ADS1219.h:14:11: error: expected unqualified-id before ')' token

   ADS1219();

           ^

ADS1219.h:12:14: error: an anonymous struct cannot have function members

 class ADS1219{

              ^

ADS1219.h:18:1: error: abstract declarator '' used as declaration

 };

 ^

adslib:3:1: error: 'ads' does not name a type

 ads = new ADS1219;

 ^

C:UsersOM222ODesktopadslibadslib.ino: In function 'void setup()':

adslib:7:3: error: 'ads' was not declared in this scope

   ads.begin();

   ^

C:UsersOM222ODesktopadslibadslib.ino: In function 'void loop()':

adslib:11:3: error: 'ads' was not declared in this scope

   ads.printHello();

   ^

exit status 1
expected unqualified-id before ')' token

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Answer 1

Your problem stems from this line:

#define ADS1219

You define the macro ADS1219 as empty. From that point on all references to ADS1219 get replaced with nothing. For example:

class ADS1219{
public:
 ADS1219();
 void begin();
 void printHello();
};

becomes:

class {
public:
 ();
 void begin();
 void printHello();
};

And

void ADS1219::begin(){
 Serial.begin(9600);
}

becomes:

void ::begin(){
 Serial.begin(9600);
}

By using the same name in your header guard as your class name you screw everything else up.

I always use strict rules for header guard macros to ensure that they never conflict with anything else. You should change yours to read something else. I would use:

#ifndef _ADS1219_H
#define _ADS1219_H

// ... content

#endif

---

You are also lacking the parenthesis in the constructor implementation:

ADS1219::ADS1219{
 Serial.println("New object created!");
}

should read:

ADS1219::ADS1219(){
 Serial.println("New object created!");
}

And you don't give your ads variable a type and you don't want to use new:

ads = new ADS1219;

should read:

ADS1219 ads;

Answer 2

Are you sure you're compiling this for C++ and not C?

In any case, you're defining

#define ADS1219

I'm not sure what that does to your class name. Have you tried to

#define ADS1219_H  // <- Standard include guard

instead? Does this yield different results.

Answer 3

I have made a lot of progress and almost everything works fine ... except I initially used strings in switch case for setting up the voltage reference and conversion modes ... it did not like it at all. I instead aimed to use enums for the same purpose but I'm getting this error now:

Arduino: 1.8.8 (Windows 10), Board: "Arduino Nano, ATmega328P (Old Bootloader)"

In file included from sketch\LibraryExample1.ino.cpp:1:0:

C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino/Arduino.h:81:18: error: expected identifier before numeric constant

 #define INTERNAL 3

                  ^

C:\Users\OM222O\Documents\Arduino\libraries\ADS1219/ADS1219.h:49:3: note: in expansion of macro 'INTERNAL'

   INTERNAL = VREF_INTERNAL,

   ^

C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino/Arduino.h:81:18: error: expected '}' before numeric constant

 #define INTERNAL 3

                  ^

C:\Users\OM222O\Documents\Arduino\libraries\ADS1219/ADS1219.h:49:3: note: in expansion of macro 'INTERNAL'

   INTERNAL = VREF_INTERNAL,

   ^

C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino/Arduino.h:81:18: error: expected unqualified-id before numeric constant

 #define INTERNAL 3

                  ^

C:\Users\OM222O\Documents\Arduino\libraries\ADS1219/ADS1219.h:49:3: note: in expansion of macro 'INTERNAL'

   INTERNAL = VREF_INTERNAL,

   ^

In file included from C:\Users\OM222O\Desktop\LibraryExample1\LibraryExample1.ino:2:0:

C:\Users\OM222O\Documents\Arduino\libraries\ADS1219/ADS1219.h:51:1: error: expected declaration before '}' token

 }adsRef_t;

 ^

exit status 1
Error compiling for board Arduino Nano.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

my ADS1219.h file is:

#ifndef ADS1219_H
#define ADS1219_H

#if (ARDUINO >=100)
  #include "Arduino.h"
#else
  #include "WProgram.h"
#endif

#include <Wire.h>

#define CONFIG_REGISTER_ADDRESS 0x20
#define STATUS_REGISTER_ADDRESS 0x24

#define MUX_MASK                0x1F
#define MUX_DIFF_0_1            0x00
#define MUX_DIFF_2_3            0x20
#define MUX_DIFF_1_2            0x40
#define MUX_SINGLE_0            0x60
#define MUX_SINGLE_1            0x80
#define MUX_SINGLE_2            0xA0
#define MUX_SINGLE_3            0xC0
#define MUX_SHORTED             0xE0

#define GAIN_MASK               0xEF
#define GAIN_ONE                0x00
#define GAIN_FOUR               0x10

#define DATA_RATE_MASK          0xF3
#define DATA_RATE_20            0x00
#define DATA_RATE_90            0x04
#define DATA_RATE_330           0x08
#define DATA_RATE_1000          0x0c

#define MODE_MASK               0xFD
#define MODE_SINGLE_SHOT        0x00
#define MODE_CONTINUOUS         0x02

#define VREF_MASK               0xFE
#define VREF_INTERNAL           0x00
#define VREF_EXTERNAL           0x01

typedef enum{
  ONE   = GAIN_ONE,
  FOUR  = GAIN_FOUR
}adsGain_t;

typedef enum{
  INTERNAL  = VREF_INTERNAL,
  EXTERNAL  = VREF_EXTERNAL
}adsRef_t;

typedef enum{
  SINGLE_SHOT   = MODE_SINGLE_SHOT,
  CONTINUOUS    = MODE_CONTINUOUS
}adsMode_t;

class ADS1219  {
  protected:
    uint8_t address;
  public:
    // Constructor 
    ADS1219(int drdy, uint8_t addr = 0x40);

    // Methods
    void begin();
    void resetConfig();
    long readSingleEnded(int channel);
    long readDifferential_0_1();
    long readDifferential_2_3();
    long readDifferential_1_2();
    long readShorted();
    void setGain(adsGain_t gain);
    void setDataRate(int rate);
    void setConversionMode(adsMode_t mode);
    void setVoltageReference(adsRef_t vref);

  private:
    void writeRegister(uint8_t data);
    uint8_t readRegister(uint8_t reg);
    long readConversionResult();
    uint8_t config;
    int data_ready;
};
#endif

and my cpp file is:

#if ARDUINO >= 100
 #include "Arduino.h"
#else
 #include "WProgram.h"
#endif

#include <Wire.h>
#include "ADS1219.h"

static uint8_t i2cRead(void) {
  #if ARDUINO >= 100
  return Wire.read();
  #else
  return Wire.receive();
  #endif
}

static void i2cWrite(uint8_t x) {
  #if ARDUINO >= 100
  Wire.write(x);
  #else
  Wire.send(x);
  #endif
}


ADS1219::ADS1219(int drdy, uint8_t addr) {
  data_ready = drdy;
  address = addr;
  config = 0x00;
}

void ADS1219::begin() {
  Wire.begin();
}

uint8_t ADS1219::readRegister(uint8_t reg){
  Wire.beginTransmission(address);
  i2cWrite(reg);
  Wire.endTransmission();
  Wire.requestFrom((uint8_t)address,(uint8_t)1);
  return i2cRead();
}

void ADS1219::writeRegister(uint8_t data){
  Wire.beginTransmission(address);
  i2cWrite(CONFIG_REGISTER_ADDRESS);
  i2cWrite(data);
  Wire.endTransmission();
}

long ADS1219::readConversionResult(){
  Wire.beginTransmission(address);
  i2cWrite(0x10);
  Wire.endTransmission();
  Wire.requestFrom((uint8_t)address,(uint8_t)3);
  byte dataMSB = i2cRead();
  byte data = i2cRead();
  byte dataLSB = i2cRead();
  long data32 = dataMSB;
  data32 <<= 8;
  data32 |= data;
  data32 <<= 8;
  data32 |= dataLSB;
  return (data32 << 8) >> 8;
}

void ADS1219::resetConfig(){
    writeRegister(0x00);
}

long ADS1219::readSingleEnded(int channel){
    if (channel > 3) return 0;
    config &= MUX_MASK;
    switch (channel){
    case (0):
      config |= MUX_SINGLE_0;
      break;
    case (1):
      config |= MUX_SINGLE_1;
      break;
    case (2):
      config |= MUX_SINGLE_2;
      break;
    case (3):
      config |= MUX_SINGLE_3;
      break;
    default:
      break;
  }
  writeRegister(config);
  while(digitalRead(data_ready)==1);
  return readConversionResult();
}

long ADS1219::readDifferential_0_1(){
  config &= MUX_MASK;
  config |= MUX_DIFF_0_1;
  writeRegister(config);
  while(digitalRead(data_ready)==1);
  return readConversionResult();
}

long ADS1219::readDifferential_2_3(){
  config &= MUX_MASK;
  config |= MUX_DIFF_2_3;
  writeRegister(config);
  while(digitalRead(data_ready)==1);
  return readConversionResult();
}

long ADS1219::readDifferential_1_2(){
  config &= MUX_MASK;
  config |= MUX_DIFF_1_2;
  writeRegister(config);
  while(digitalRead(data_ready)==1);
  return readConversionResult();
}

long ADS1219::readShorted(){
  config &= MUX_MASK;
  config |= MUX_SHORTED;
  writeRegister(config);
  while(digitalRead(data_ready)==1);
  return readConversionResult();
}

void ADS1219::setGain(adsGain_t gain){
    config &= GAIN_MASK;
    config |= gain;
  writeRegister(config);
}

void ADS1219::setDataRate(int rate){
    config &= DATA_RATE_MASK;
    switch (rate){
    case (20):
      config |= DATA_RATE_20;
      break;
    case (90):
      config |= DATA_RATE_90;
      break;
    case (330):
      config |= DATA_RATE_330;
      break;
    case (1000):
      config |= DATA_RATE_1000;
      break;
    default:
      break;
  }
  writeRegister(config);
}

void ADS1219::setConversionMode(adsMode_t mode){
    config &= MODE_MASK;
    config |= mode;
  writeRegister(config);
}

void ADS1219::setVoltageReference(adsRef_t vref){
    config &= VREF_MASK;
    config |= vref;
  writeRegister(config);
}

it seems to be passing Gain (or maybe hasn't compiled that yet) but failing on the reference selection ... I don't know what I should change in order to fix the issue.

Edit: I'm really hoping it's not another naming convention thing ... if it is, I'm sorry but C++ seems to waaaaayyyy too picky about names in general