Code meaning for Arduino Uno

Projects Programming
5

pinMode(8, INPUT);
This says make pin D8 on the Arduino an input pin (at power up time it already is an input though)

Another option to use is
pinMode(8, INPUT_PULLUP);
this says make the pin D8 an input and also turn on the internal 20k pullup resistor for this pin.

double is the data ‘type’ for the variable you are defining

on the Arduino , double is the same size as float .

Number 'type's.

  • boolean (8 bit) - simple logical true/false, Arduino does not use single bits for bool

  • byte (8 bit) - unsigned number from 0 to 255

  • char (8 bit) - signed number from -128 to 127. The compiler will attempt to interpret this data type as a character in some circumstances, which may yield unexpected results

  • unsigned char (8 bit) - same as 'byte'; if this is what you're after, you should use 'byte' instead, for reasons of clarity

  • word (16 bit) - unsigned number from 0 to 65535

  • unsigned int (16 bit)- the same as 'word'. Use 'word' instead for clarity and brevity

  • int (16 bit) - signed number from -32768 to 32767. This is most commonly what you see used for general purpose variables in Arduino example code provided with the IDE

  • unsigned long (32 bit) - unsigned number from 0 to 4,294,967,295. The most common usage of this is to store the result of the millis() function, which returns the number of milliseconds the current code has been running

  • long (32 bit) - signed number from -2,147,483,648 to 2,147,483,647

float (32 bit) - signed number from -3.4028235E38 to 3.4028235E38. Floating point on the Arduino is not native; the compiler has to jump through hoops to make it work. If you can avoid it, you should. We'll touch on this later. Sparkfun.

You select the 'type' best suited for your variables.

ex:

  • your variable does not change and it defines a pin on the Arduino. const byte limitSwitchPin = 34;
  • since an analog variable can be 0 to 1023, a byte will not do, you can select 'int'. int temperature;
  • if your variable needs to be within -64 to +64 a 'char' will do nicely. char joystick;
  • if your variable is used for ASCII then you need type 'char',
    char myText[] = {"Raspberry Pie Smells"};
  • if your variable enables some code then boolean can be used. boolean enableFlag = false;
  • millis() returns the time in ms since rebooting, unsigned long currentTime = millis();

Serial.println
Says to print something to the serial monitor the to add a line feed.