I'm trying to use Adafruit's LED Backpack library within a custom class. When I use the Adafruit library directly within a sketch, it compiles fine. When I use an example sketch provided with the library, it compiles fine. However when I create an instance of my custom class with the Adafruit object within it, I get the following error:

In file included from sketch_feb18a.ino:6: /Users/lawnmowerlatte/Documents/Arduino/libraries/Bargraph/bargraph.h:18: error: 'Adafruit_24bargraph' does not name a type

All the reasons I've seen for this error stem from the library being missing or otherwise incorrectly installed. However, since I can use it directly, I think something else must be wrong.


#include <Adafruit_LEDBackpack.h>
#include <Adafruit_GFX.h>
Adafruit_24bargraph bar = Adafruit_24bargraph();

void setup() { }
void loop() { }

Not Working

#include <bargraph.h>
Bargraph bargraph = Bargraph("Test", "api", 0);

void setup() { }
void loop() { }


#ifndef Bargraph_h
#define Bargraph_h

#include <Adafruit_GFX.h>
#include <Adafruit_LEDBackpack.h>

#if (ARDUINO >= 100)
#include <Arduino.h>
#include <WProgram.h>

class Bargraph {
  public :
    String name;
    String api;
    Adafruit_24bargraph bar;

    Bargraph(String _name, String _api, int _device,
        String _type="Default");

    void set(String _value);
    void setMax(String _max);
    void update();
    void print();

  private :
    int display[24];

    long max;
    long value;
    int device;
    int size;
    String type;

    void format();
    void write();



#define OFF 0
#define RED 1
#define YELLOW 2
#define GREEN 3

#include <bargraph.h>

#if (ARDUINO >= 100)
#include <Arduino.h>
#include <WProgram.h>

Bargraph::Bargraph(String _name, String _api, int _device, String _type) : bar() {
    name        = _name;
    api         = _api;
    max         = _max.toLong();
    device      = _device;
    type        = _type;
    value       = 0;

    for (int i=0; i<24; i++) {
        display[i] = OFF;


**Methods Omitted for Brevity**

Can anyone explain what's going on here? I'm pretty certain my class syntax is correct as I have other object-in-object relationships working. I can post code to GitHub if anyone would like to see more context.


I think these lines still need to be in your main sketch file (in addition to being in your custom class file):

#include <Adafruit_LEDBackpack.h>
#include <Adafruit_GFX.h>

If I remember the Arduino IDE quirks correctly, it uses the #include directives in the main sketch file to determine which libraries to actually link. It's one of those annoying features that was intended to be beginner-friendly but sometimes just makes things more confusing.

  • Thanks for the answer. I tried this, but then I get a ton of redefinition and previous definition errors. If I wrap the Adafruit library in ifndef blocks, it works! Do you have any ideas why they wouldn't have put that in? It seems like good practice to do so. – lawnmowerlatte Feb 19 '15 at 20:09
  • @lawnmowerlatte - That's surprising. I can't see any reason that it wouldn't be there already. – Peter Bloomfield Feb 19 '15 at 21:06

If you used the serial port, Arduino sometimes causes confusion. Close Arduino IDE and delete files in folder C:/users/[your name]/AppData/Local/Temp/ Its working. Regards

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