Error message "undefined reference"

ludwig001 · February 19, 2023, 1:02pm

I've read a few posts on this topic, but I'm getting nowhere:

I want to make my code more readable using object oriented structures. However, I haven't gotten far and am failing at the basics. I now have three tabs, the main program, a header tab and a CPP tab. The three are neatly stored as separate files.

Here is my "stripped down" code:

IO Tab RD40

#include "my_RD40.h"

my_RD40 RD40;          // generate RD40 object

void setup()
{  
  // Serial port for debugging purposes
  Serial.begin(115200);

  RD40.setTime();
  RD40.getTime();
  Serial.printf("Zeit: %d:%d:%d\n", RD40.Hour(), RD40.Min(), RD40.Sec());
}

void loop() 
{
    RD40.getTime();
}

my_RD40.h


#ifndef my_RD40_H
#define my_RD40_H

#include <Arduino.h>

class my_RD40 {
  private:
    int _Sec;   // Sekunden (0-59)
    int _Min;   // Minuten (0-59)
    int _Hour;  // Stunden (0-23)
    int _Mday;  // Tag des Monats (1-31)
    int _Mon;   // Monat (0-11)
    int _Year;  // Jahr - 1900
    int _Wday;  // Tag der Woche (0-6, Sonntag = 0)

  public:
    my_RD40();  // Constructor

    void setTime();
    void getTime();
    int Sec();   
    int Min();   
    int Hour();  
    int Mday();  
    int Mon();   
    int Year();  
    int Wday();  
};

#endif

my_RD40.cpp

#include "my_RD40.h"
#include <Wire.h>
#include <TimeLib.h>


#define SDA 2
#define SCL 0
#define LOCATION TZ_Europe_Berlin                   // replace with your location
#define NTP "pool.ntp.org"

my_RD40::my_RD40() {
  // Setup I2C
  Wire.begin(SDA,SCL);                              // SDA=GPIO2 /  SCL=GPIO0 ==> registers the controller as I2C Master
  Wire.setClock(200000L);
}

void my_RD40::setTime() {  
  configTime(LOCATION, NTP);
  while (!time(nullptr)) {                                      // Wait until time is initialized
    delay(1000);
  }
  setTime(hour(), minute(), second(), day(), month(), year());  // Set internal clock
}

void my_RD40::getTime() {
  time_t now = time(nullptr);                                   // recall time from internal clock
  _Hour = hour(now);
  _Min = minute(now);
  _Sec = second(now);
  _Mday = day(now);
  _Mon = month(now);
  _Year = year(now);
  _Wday = weekday(now);
}

int my_RD40::Sec() {
  return _Sec;
}

int my_RD40::Min() {
  return _Min;
}

int my_RD40::Hour() {
  return _Hour;
}

int my_RD40::Mday() {
  return _Mday;
}

int my_RD40::Mon() {
  return _Mon;
}

int my_RD40::Year() {
  return _Year;
}

int my_RD40::Wday() {
  return _Wday;
}

I get several "undefined reference" errors when compiling. It looks like they are pointing to the main tab.

Any help would be appreciated.

Idahowalker · February 19, 2023, 1:06pm

Would you be interested in helping me help you?

Post the error messages.

ludwig001 · February 19, 2023, 1:29pm

fair enough. I have deleted some path information though:

c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: sketch\RD40.ino.cpp.o:(.text.setup+0xc): undefined reference to `_ZN7my_RD407setTimeEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: sketch\RD40.ino.cpp.o:(.text.setup+0x10): undefined reference to `_ZN7my_RD407getTimeEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: sketch\RD40.ino.cpp.o:(.text.setup+0x14): undefined reference to `_ZN7my_RD404HourEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: sketch\RD40.ino.cpp.o:(.text.setup+0x18): undefined reference to `_ZN7my_RD403MinEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: sketch\RD40.ino.cpp.o:(.text.setup+0x1c): undefined reference to `_ZN7my_RD403SecEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: sketch\RD40.ino.cpp.o: in function `setup':
C:\Users\.....\RD40/RD40.ino:23: undefined reference to `_ZN7my_RD407setTimeEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: C:\Users\.....\RD40/RD40.ino:28: undefined reference to `_ZN7my_RD407getTimeEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: C:\Users\.....\RD40/RD40.ino:28: undefined reference to `_ZN7my_RD404HourEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: C:\Users\.....\RD40/RD40.ino:29: undefined reference to `_ZN7my_RD403MinEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: C:\Users\.....\RD40/RD40.ino:30: undefined reference to `_ZN7my_RD403SecEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: sketch\RD40.ino.cpp.o: in function `loop':
C:\Users\.....\RD40/RD40.ino:31: undefined reference to `_ZN7my_RD407getTimeEv'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: C:\Users\.....\RD40/RD40.ino:40: undefined reference to `_ZN7my_RD40C1Ev'
c:/users/...../appdata/local/arduino15/packages/esp8266/tools/xtensa-lx106-elf-gcc/3.0.4-gcc10.3-1757bed/bin/../lib/gcc/xtensa-lx106-elf/10.3.0/../../../../xtensa-lx106-elf/bin/ld.exe: sketch\RD40.ino.cpp.o: in function `_GLOBAL__sub_I_RD40':
C:\Users\.....\RD40/RD40.ino:40: undefined reference to `_ZN7my_RD40C1Ev'
collect2.exe: error: ld returned 1 exit status
Mehrere Bibliotheken wurden für "SD.h" gefunden
 Benutzt: C:\Users\.....\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2\libraries\SD
 Nicht benutzt: C:\Program Files (x86)\Arduino\libraries\SD
exit status 1
Fehler beim Kompilieren für das Board Generic ESP8285 Module.

I trust this helps

Idahowalker · February 19, 2023, 3:19pm

I mention this because the error message posted points in this direction. Thanks for posting the error message.

I see that GPIO_NUM_2 of the ESP32 developer module is being used for the SDA line to transmit I2C data.

Most ESP32 developer boards have the onboard LED at GPIO_2. I have found that the circuit required to run the LED may cause issues when transmitting data via GPIO_NUM_2.

The natural I2C pins for the ESP32 under the Arduino IDE should be used for I2C; see your developers board pinout.

The error message also points to an issue in loop() and setup(), I'd comment all the code in loop(). Comment out all

void setup()
{  
  // Serial port for debugging purposes
  Serial.begin(115200);

  RD40.setTime();
  //RD40.getTime();
  //Serial.printf("Zeit: %d:%d:%d\n", RD40.Hour(), RD40.Min(), RD40.Sec());
}

and see if the error is reproduced.

Also, for setting/getting the ESP32's time I prefer to use the ESP32Time library. GitHub - fbiego/ESP32Time: An Arduino library for setting and retrieving internal RTC time on ESP32 boards, which seems to 'understand' the ESP32's way a bit better than other time libraries.

ludwig001 · February 19, 2023, 4:41pm

Thank you for the reply.

I should have mentioned, that I am using an ESP8266-01s. As you know, this tiny board only has two IO pins available.

I2C
I do have running (and very comprehensive) C code for the controller, which I just would like to restructure. I found that it actually is possible to use the two I/O lines on the ESP-01s as I2C pins.
ESP32Time
Thank you for the hint. However, as I run the code on an ESP8266, this might not work. I have been struggling with the various time libraries (time.h, tineLib.h, etc.) for long. I just do not understand why such a base function is so cumbersome to deal with.

The thought behind the my_RD40 class is to create a class that manages the hardware layer (i2C, Wifi, and time). However, I failed with the class structure already.

Unfortunately, I am traveling now and can only continue to work on the code next weekend. I will let you know, what I find out.

ludwig001 · February 24, 2023, 9:46pm

just in case someone is interested:

the error was in the method my_RD40::setTime(). Inside this method I had used the function setTime(hour(), minute(), second(), day(), month(), year()). This is a function of TimeLib.h. However, I had used the same name (namely setTime()) also for my own method. Thus there was the name twice - that was then too much of a good thing.

Just for the eternal files of the forum the corrected and working code:

RD40

#include "my_RD40.h"

my_RD40 RD40;                                                       // generate RD40 object

void setup(){
  
  // Serial port for debugging purposes
  Serial.begin(115200);

  RD40.setMyTime();
  RD40.getMyTime();
  Serial.printf("Zeit: %d:%d:%d\n", RD40.Hour(), RD40.Min(), RD40.Sec());
}

void loop() {
    RD40.getMyTime();
}

my_RD40.h

#ifndef my_RD40_H
#define my_RD40_H

#include <Arduino.h>

class my_RD40 {
  private:
    int _Sec;   // Sekunden (0-59)
    int _Min;   // Minuten (0-59)
    int _Hour;  // Stunden (0-23)
    int _Mday;  // Tag des Monats (1-31)
    int _Mon;   // Monat (0-11)
    int _Year;  // Jahr - 1900
    int _Wday;  // Tag der Woche (0-6, Sonntag = 0)

    
  public:
    my_RD40();  // Constructor

    void setMyTime();
    void getMyTime();
    int Sec();   
    int Min();   
    int Hour();  
    int Mday();  
    int Mon();   
    int Year();  
    int Wday();  
};

#endif

my_RD40.cpp

#include "my_RD40.h"
#include <TimeLib.h>
#include <TZ.h>
#include <Wire.h>

#define _SDA 2
#define _SCL 0
#define LOCATION TZ_Europe_Berlin                   // replace with your location
#define NTP "pool.ntp.org"

my_RD40::my_RD40() {
  // Setup I2C
  Wire.begin(_SDA,_SCL);                              // SDA=GPIO2 /  SCL=GPIO0 ==> registers the controller as I2C Master
  Wire.setClock(200000L);
}

void my_RD40::setMyTime() {  
  configTime(LOCATION, NTP);
  while (!time(nullptr)) {                                      // Wait until time is initialized
    delay(1000);
  }
  setTime(hour(), minute(), second(), day(), month(), year());  // Set internal clock
}

void my_RD40::getMyTime() {
  time_t now = time(nullptr);                                   // recall time from internal clock
  _Hour = hour(now);
  _Min = minute(now);
  _Sec = second(now);
  _Mday = day(now);
  _Mon = month(now);
  _Year = year(now);
  _Wday = weekday(now);
}

int my_RD40::Sec() {
  return _Sec;
}

int my_RD40::Min() {
  return _Min;
}

int my_RD40::Hour() {
  return _Hour;
}

int my_RD40::Mday() {
  return _Mday;
}

int my_RD40::Mon() {
  return _Mon;
}

int my_RD40::Year() {
  return _Year;
}

int my_RD40::Wday() {
  return _Wday;
}

noiasca · February 25, 2023, 12:07pm

You are on an ESP8266?

Don't use an external NTP library. NTP + DST is part of the ESP core since years. You don't need an external library for that.

https://werner.rothschopf.net/202011_arduino_esp8266_ntp_en.htm

p.s.: there is a very active German forum in the international section for your next question.

ludwig001 · February 25, 2023, 3:29pm

Thank you for the comment. Very helpful link. I have adapted my code.

system · August 24, 2023, 3:30pm

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