Reads the value from a specified digital pin, either HIGH or LOW.

Syntax digital(pin)

Parameters pin: the Arduino pin number you want to read

Returns: High or Low

Write a HIGH or a LOW value to a digital pin.

If the pin has been configured as an OUTPUT with pinMode(), its voltage will be set to the corresponding value: 5V (or 3.3V on 3.3V boards) for HIGH, 0V (ground) for LOW.

Syntax digitalWrite(pin, value)

Parameters pin: the Arduino pin number. value: HIGH or LOW.

Returns: High or Low

Configures the specified pin to behave either as an input or an output. See the Digital Pins page for details on the functionality of the pins.

As of Arduino 1.0.1, it is possible to enable the internal pullup resistors with the mode INPUT_PULLUP. Additionally, the INPUT mode explicitly disables the internal pullups.

Syntax pinMode(pin, mode)

Parameters pin: the Arduino pin number to set the mode of. mode: INPUT, OUTPUT, or INPUT_PULLUP. See the Digital Pins page for a more complete description of the functionality.

Returns: Nothing

Writes an analog value (PWM wave) to a pin. Can be used to light a LED at varying brightnesses or drive a motor at various speeds. After a call to analogWrite(), the pin will generate a steady rectangular wave of the specified duty cycle until the next call to analogWrite() (or a call to digitalRead() or digitalWrite()) on the same pin.

Syntax analogWrite(pin, value)

Parameters pin: the Arduino pin to write to. Allowed data types: int. value: the duty cycle: between 0 (always off) and 255 (always on). Allowed data types: int.

Returns: Nothing

Analyse if a char is alpha (that is a letter). Returns true if thisChar contains a letter.

Syntax isAlpha(thisChar)

Parameters thisChar: variable. Allowed data types: char.

Returns: true: if thisChar is alpha.