![]() The "setPin()" functionality can be done in the 'constructor' so we specify the pin when we create each instance. Void blink(const unsigned long interval) Note that now BlinkLib.h needs some definitions from Arduino.h ('byte', 'LOW', 'pinMode'.) so we include Arduino.h at the top. This goes into BlinkLib.h in place of the shared function prototypes. Let's create an object class named 'Blinker'. You can then make multiple 'instances' of the object, each with its own variables. To fix that, we 'encapsulate' the functionality of the library into an 'object'. One problem with the library is that you can only blink one LED because the library only has one set of global variables. Library header: void blink(unsigned long) Move the declaration of 'ledPin' into BlinkLib.cpp. We need a way for setup() to set the pin mode so we create another function in BlinkLib.cpp: void setPin(int pin) We used 'ledPin' in setup() so we left the declaration there, but now BlinkLib.cpp needs the declaration. That leaves you with the next error: BlinkLib.cpp:21:18: error: 'ledPin' was not declared in this scope ![]() This will allow the main sketch to see a declaration of "blink". Create a new tab named BlinkLib.h (h for 'header'). ![]() This is a good time to create another tab that shares the library declarations with the sketch that uses the library. That's because the main sketch no longer contains a declaration for the blink() function. Now you get the error: sketch_jan05a:13:3: error: 'blink' was not declared in this scope While you're at it, move 'ledState' and 'interval', too. In this case, only the library needs it so move that declaration to the top of BlinkLib.cpp. This is because that declaration didn't get moved to the library. The next error is: BlinkLib.cpp:6:23: error: 'previousMillis' was not declared in this scope ![]() Add that line to the top of BlinkLib.cpp and do another Verify. This is because, unlike a '.ino' file '.cpp' files don't getĪutomatically inserted at compile time. The first is: BlinkLib.cpp:3:33: error: 'millis' was not declared in this scope If you try to Verify your sketch now you will find some errors. Now cut the 'blink' function out of the main tab and paste it into the new tab. At the right end of the bar just above the sketch is a little triangle in a square. This sketch does exactly the same thing as before. The next step is to move the guts of the library behavior into a function. set the LED with the ledState of the variable: If (currentMillis - previousMillis >= interval) You can find the full source under File->Examples->02.Digital->BlinkWithoutDelay so I am removing most of the comments for compactness. Since you want your library to blink an LED, let's start with the BlinkWithoutDelay example. Arduino has quite a few built-in libraries.When you are first starting out developing a library you can start with a sketch. Then you're using the Serial() library built in to Arduino. You may not realize it, but you're probably already using libraries! If you've used: Serial.print("Hello world!") Infrared Remote is a great library for reading signals from IR remotes and controlling IR remote based things like TVs and sound systems.It’s great for non-contact capacitive switches and field sensing. Capacitive Sensor is the library we covered in this tutorial.EEPROM is a built-in library that allows users to read and store settings within the non-volatile memory of the ATmega328.MP3Shield is a great example of a customer of SparkFun taking complex example code and creating a very good library to make the device easier to use.Great for datalogging! Be sure to checkout all the examples included with the library. Sdfat is a very good library that allows you to read and write files to SD cards.SevSeg is a library we wrote to make controlling 7-segment displays easier.TinyGPS is the gold standard for interfacing to GPS modules.If you're looking for some great libraries to get started with, here are some of our favorites: Share on Twitter Share on Facebook Pin It Resources and Going Further ![]()
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