IFD:Interaktive Elektronik 2012/Arduino programming beginners: Difference between revisions

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-Use an LED on pin 13:<br>
+[[File:LED_Pin_13_Steckplatine.png | thumb | Using an LED on pin 13]]
-[[File:LED_Pin_13_Steckplatine.png]]<br>
-Use an LED on pin 3:<br>
+[[File:LED_Pin_3_Steckplatine.png | thumb | Use an LED on pin 3]]<br>
-[[File:LED_Pin_3_Steckplatine.png]]<br>
-Use a Potentiometer and LED:<br>
+[[File:LED_Pin_3_Potentiometer_A0_Steckplatine.png | thumb |Use a Potentiometer and LED]]<br>
-[[File:LED_Pin_3_Potentiometer_A0_Steckplatine.png]]<br>
+We covered in the first lesson:
+* Arduino file format (pde and ino)
+* Functions of the buttons of the Arduino IDE
+* Opening the Serial monitor.
+* Going through the blink example.
+** setup:
+*** set pin 13 to output
+** loop:
+*** set pin 13 to be turned on
+*** wait one second
+*** set pin 13 to be turned off
+*** wait one second
+*** repeat the loop.
+<br clear="all">
+Today:
+* introduce the concept of variables.
+* introduce the "if" condition.
+* introduce functions.
+Introducing variables.
+int (means an integer number: 0 1 2 3 4 5 6 ... and also negative numbers. limits: -32,768 to 32,767
+there are other kinds of variables. we only use int for simplicity in this lesson.
+valid names for variables: otto, lemonade24 and pudding
+not allowed names for variables: ööö äää 1234Otto (must start with an alphanumeric character)
+better names for variables: delayTimeOff, pinNumber, delayTimeOn
+=== using variables ===
+variables are a place to store numbers in the memory. They make life easier in many cases:
+replace pin number by a variable - changing pin is much less tedious and cumbersome.
+replace delay by a variable - doesn't seem useful first. but:
+Changing variables during runtime (while the program is running) is also possible:
+'''Having some random fun'''
+<source lang="c">delayTime = random(1000);</source>
+will assign a random number from 1 to 1000.
+Some other useful ways to assign a new value to a variable:
+today we use: + - *
+increasing the delay time:
+<source lang="c">
+delaytime = 100;
+delaytime = delaytime + 100;
+</source>
+in the first line delaytime gets the new value 100
+in the second line something apparently strange happens - how is this possible?
+This line is not meaning a mathematical equality. The right side of the equals sign (=) is calculated first and then assigned to the left side of the equals sign. The following 3 steps happen - invisible for you inside the program when it's running:
+'''Step 1:''' The old delaytime is replaced by 100
+<source lang="c"> delaytime = 100 + 100 </source>
+'''Step 2:''' The values on the right side of the equals sign are added and assigned to the variable:
+<source lang="c"> delaytime = 200 </source>
+Now the value of delaytime is 200.
+=== a new kind of output: ''analogWrite'' ===
+Since we are working with LEDs a desirable feature would be to set the brightness. ''analogWrite'' lets us do this: <source lang="c"> analogWrite(pinNumber,Brightness); </source>
+or more generally since it is not only meant for brightness:
+<source lang="c"> analogWrite(pinNumber,analogValue); </source>