title

description

Functions

Digital I/O

Method & Parameters	Description	Returns
`int digitalRead(int pin)`	Reads the state of a digital pin.	`int`
`void digitalWrite(int pin, int state)`	Writes a state to a digital pin.	Nothing
`void pinMode(int pin, int mode)`*	Define the mode of a pin.	Nothing

*Available modes are:

INPUT (0)
OUTPUT (1)
INPUT_PULLUP (2)
INPUT_PULLDOWN (3)
OUTPUT_OPENDRAIN (4)

Analog I/O

Method & Parameters	Description	Returns
`int analogRead(int pin)`	Reads the value of an analog pin in a 10-bit resolution (0-1023).*	`int`
`void analogReadResolution(int resolution)`	Sets ADC read resolution in bits.	Nothing
`void analogReference(int reference)`	Changes the voltage reference for a board.**	Nothing
`void analogWrite(int pin, int value)`	Writes a value to a PWM supported pin in a 8-bit resolution (0-255).**	Nothing
`void analogWriteResolution(int resolution)`	Sets write resolution for a board.	Nothing

*The value range changes based on the resolution. 0-1023 is 10-bit resolution, 0-4096 is 12-bit and so on.
**Each board/architecture has a set of different reference voltages available.
***The value range changes based on the resolution. 0-255 is default (8-bit).

Advanced I/O

Method & Parameters	Description	Returns
`void tone(int pin, int frequency, long duration)`	Generates a square wave on specified pin, with 50% duty cycle.	Nothing
`void noTone(int pin)`	Stops generation of square wave on the specified pin.	Nothing
`long pulseIn(int pin, int state, long timeout)`	Reads a pulse (either HIGH or LOW) on a pin and returns the length of the pulse (in microseconds)	`long`
`long pulseInLong(int pin, int state, long timeout)`	Returns the length of the pulse (in microseconds)	`long`
`int shiftIn(int pin, int clockPin, int bitOrder)`*	Shifts in a byte of data one bit at a time, and returns the value of the bit read.	`byte`
`void shiftOut(int pin, int clockPin, int bitOrder, byte value)`**	Shifts out a byte of data one bit at a time.	Nothing

*The bitOrder parameter is either MSBFIRST (1) or LSBFIRST (0) (most / least significant bits).
**The pin used for shiftOut() needs to be configured as an OUTPUT, using pinMode()

Time

Method & Parameters	Description	Returns
`void delay(long milliseconds)`	Freezes program execution for specified number of milliseconds.	Nothing
`void delayMicroseconds(int microseconds)`	Freezes program execution for specified number of microseconds.	Nothing
`long millis()`	Returns milliseconds passed since program start.	`long`
`long micros()`	Returns microseconds passed since program start.	`long`

Math

Method & Parameters	Description	Returns
`int abs(int value)`	Calculates the absolute value of a number.	`int`
`int constrain(int value, int min, int max)`	Constrains a number to be within a range.	`int`
`long map(long val, long min, long max, long newMin, long newMax)`	Re-maps a number from one range to another.	`long`
`int max(int val1, int val2)`	Returns the greater of two values.	`int`
`int min(int val1, int val2)`	Returns the smaller of two values.	`int`
`double pow(double base, double exponent)`	Raises a base to the power of an exponent.	`double`
`int sq(int value)`	Calculates the square of a number.	`int`
`double sqrt(double value)`	Calculates the square root of a number.	`double`

Trigonometry

Method & Parameters	Description	Returns
`cos(double angle)`	Calculates the cosine of an angle in radians.	`double`
`sin(double angle)`	Calculates the sine of an angle in radians.	`double`
`tan(double angle)`	Calculates the tangent of an angle in radians.	`double`

Characters

Method & Parameters	Description	Returns
`boolean isAlpha(char c)`	Checks if the character is an alphabetic character.	`boolean`
`boolean isAlphaNumeric(char c)`	Checks if the character is an alphanumeric character.	`boolean`
`boolean isAscii(char c)`	Checks if the character is a 7-bit ASCII character.	`boolean`
`boolean isControl(char c)`	Checks if the character is a control character.	`boolean`
`boolean isDigit(char c)`	Checks if the character is a digit (0-9).	`boolean`
`boolean isGraph(char c)`	Checks if the character is a printable character, excluding space.	`boolean`
`boolean isHexadecimalDigit(char c)`	Checks if the character is a hexadecimal digit (0-9, A-F, a-f).	`boolean`
`boolean isLowerCase(char c)`	Checks if the character is a lowercase alphabetic character.	`boolean`
`boolean isPrintable(char c)`	Checks if the character is a printable character, including space.	`boolean`
`boolean isPunct(char c)`	Checks if the character is a punctuation character.	`boolean`
`boolean isSpace(char c)`	Checks if the character is a whitespace character.	`boolean`
`boolean isUpperCase(char c)`	Checks if the character is an uppercase alphabetic character.	`boolean`
`boolean isWhitespace(char c)`	Checks if the character is a whitespace character according to `isSpaceChar()` method.	`boolean`

Random Numbers

Method & Parameters	Description	Returns
`int random()`	Generates a pseudo-random number between 0 and `RAND_MAX`.	`int`
`void randomSeed(unsigned long seed)`	Seeds the random number generator.	Nothing

Bits and Bytes

Method & Parameters	Description	Returns
`boolean bit(int value, int bitNumber)`	Gets the value of a specific bit.	`boolean`
`void bitClear(int &value, int bit)`	Clears a specific bit.	Nothing
`boolean bitRead(int value, int bitNumber)`	Reads the value of a specific bit.	`boolean`
`void bitSet(int &value, int bit)`	Sets a specific bit.	Nothing
`void bitWrite(int &value, int bit, int bitValue)`	Writes a value to a specific bit.	Nothing
`byte highByte(int value)`	Returns the high byte of an `int`.	`byte`
`byte lowByte(int value)`	Returns the low byte of an `int`.	`byte`

External Interrupts

Method & Parameters	Description	Returns
`void attachInterrupt(int pin, void (*function)(void), int mode)`	Attaches an interrupt to a specific pin.	Nothing
`void detachInterrupt(int pin)`	Detaches an interrupt from a specific pin.	Nothing

Interrupts

Method & Parameters	Description	Returns
`void interrupts()`	Enables interrupts globally.	Nothing
`void noInterrupts()`	Disables interrupts globally.	Nothing

Stream

Method & Parameters	Description	Returns
`int available()`	Returns the number of bytes available in the serial buffer.	`int`
`int read()`	Reads the next byte from the serial buffer.	`int`
`void flush()`	Waits for the transmission of outgoing serial data to complete.	Nothing
`int find(char *target)`	Searches for a target string in the serial buffer.	`int`
`int findUntil(char target, char terminate)`	Searches for a target string until a specified termination string is found.	`int`
`int peek()`	Returns the next byte in the serial buffer without removing it.	`int`
`int readBytes(char *buffer, int length)`	Reads characters from the serial buffer into a buffer.	`int`
`int readBytesUntil(char terminator, char *buffer, int length)`	Reads characters from the serial buffer into a buffer until a terminator is found.	`int`
`String readString()`	Reads characters from the serial buffer into a String until a newline character is found.	`String`
`String readStringUntil(char terminator)`	Reads characters from the serial buffer into a String until a specified terminator is found.	`String`
`int parseInt()`	Reads characters from the serial buffer and converts them to an integer.	`int`
`float parseFloat()`	Reads characters from the serial buffer and converts them to a float.	`float`
`void setTimeout(unsigned long timeout)`	Sets the maximum duration for `find()`, `findUntil()`, `parseInt()`, and `parseFloat()`.	Nothing

Serial

Method & Parameters	Description	Returns
`if(Serial)`	Checks if the Serial object is available.	`boolean`
`int available()`	Returns the number of bytes available for reading.	`int`
`int availableForWrite()`	Returns the number of bytes available for writing.	`int`
`void begin(unsigned long baudrate)`	Initializes the Serial communication with the specified baud rate.	`void`
`void end()`	Ends the Serial communication.	`void`
`int find(char *target)`	Searches for a target string in the serial buffer.	`int`
`int findUntil(char target, char terminate)`	Searches for a target string until a specified termination string is found.	`int`
`void flush()`	Waits for the transmission of outgoing serial data to complete.	`void`
`float parseFloat()`	Reads characters from the serial buffer and converts them to a float.	`float`
`int parseInt()`	Reads characters from the serial buffer and converts them to an integer.	`int`
`int peek()`	Returns the next byte in the serial buffer without removing it.	`int`
`size_t print()`	Prints data to the serial port.	`size_t`
`size_t println()`	Prints data to the serial port followed by a newline character.	`size_t`
`int read()`	Reads the next byte from the serial buffer.	`int`
`int readBytes(char *buffer, size_t length)`	Reads characters from the serial buffer into a buffer.	`int`
`int readBytesUntil(char terminator, char *buffer, size_t length)`	Reads characters from the serial buffer into a buffer until a terminator is found.	`int`
`String readString()`	Reads characters from the serial buffer into a String until a newline character is found.	`String`
`String readStringUntil(char terminator)`	Reads characters from the serial buffer into a String until a specified terminator is found.	`String`
`void setTimeout(unsigned long timeout)`	Sets the maximum duration for `find()`, `findUntil()`, `parseInt()`, and `parseFloat()`.	`void`
`size_t write(uint8_t)`	Writes a byte to the serial port.	`size_t`
`void serialEvent()`	Called when data is available in the serial buffer.	`void`

SPI

Method & Parameters	Description	Returns
`SPISettings(uint32_t clock, uint8_t bitOrder, uint8_t dataMode)`	Creates an SPISettings object with the specified clock, bit order, and data mode.	`SPISettings`
`void begin()`	Initializes the SPI library.	`void`
`void beginTransaction(SPISettings settings)`	Begins an SPI transaction with the specified settings.	`void`
`void endTransaction()`	Ends the current SPI transaction.	`void`
`void end()`	Ends the SPI library.	`void`
`void setBitOrder(uint8_t bitOrder)`	Sets the bit order (MSBFIRST or LSBFIRST) for SPI communication.	`void`
`void setClockDivider(uint8_t divider)`	Sets the clock divider for SPI communication.	`void`
`void setDataMode(uint8_t dataMode)`	Sets the data mode for SPI communication.	`void`
`byte transfer(byte value)`	Transfers a byte over SPI.	`byte`
`void usingInterrupt(int interruptNumber)`	Specifies which interrupt to use for SPI transactions.	`void`

I2C (Wire)

Method & Parameters	Description	Returns
`void begin()`	Initializes the Wire library.	`void`
`void end()`	Ends the Wire library.	`void`
`int requestFrom(int address, int quantity)`	Requests data from a slave device with the specified address and quantity of bytes.	`int`
`void beginTransmission(int address)`	Begins a transmission to the slave device with the specified address.	`void`
`int endTransmission()`	Ends the transmission and returns the status.	`int`
`size_t write(uint8_t data)`	Writes a byte to the I2C bus.	`size_t`
`int available()`	Returns the number of bytes available for reading.	`int`
`int read()`	Reads a byte from the I2C bus.	`int`
`void setClock(uint32_t frequency)`	Sets the I2C clock frequency.	`void`
`void onReceive(void (*function)(int))`	Sets a function to be called when data is received by the slave.	`void`
`void onRequest(void (*function)(void))`	Sets a function to be called when the master requests data from the slave.	`void`
`void setWireTimeout(uint32_t timeout)`	Sets the timeout for I2C operations.	`void`
`void clearWireTimeoutFlag()`	Clears the timeout flag.	`void`
`bool getWireTimeoutFlag()`	Returns the timeout flag status.	`bool`

Variables

Enums

Enum Type	Enumeration	Description
`PinStatus`	`HIGH / LOW`	Logical HIGH and LOW values (`1` and `0`).
`PinMode`	`INPUT` / `OUTPUT` / `INPUT_PULLUP` / `INPUT_PULLDOWN` / `OUTPUT_OPENDRAIN`	Constants for specifying pin modes (`0`, `1`, `2`, `3`, `4`).
	`LED_BUILTIN`	Constant representing the built-in LED pin.*
	`true / false`	Boolean constants for true and false (`1` and `0`).

Conversion

Method & Parameter	Description
`(unsigned int)`	Type casting to unsigned int.
`(unsigned long)`	Type casting to unsigned long.
`byte()`	Type casting to byte.
`char()`	Type casting to char.
`float()`	Type casting to float.
`int()`	Type casting to int.
`long()`	Type casting to long.
`word()`	Type casting to word.

Data Types

Method & Parameter	Description
`array`	Collection of variables of the same type.
`bool`	Boolean data type.
`boolean`	Boolean data type (synonym for bool).
`byte`	8-bit unsigned data type.
`char`	8-bit character data type.
`double`	Double-precision floating-point data type.
`float`	Single-precision floating-point data type.
`int`	Integer data type.
`long`	Long integer data type.
`short`	Short integer data type.
`size_t`	Unsigned integer data type.
`string`	Sequence of characters (not a primitive type).
`String()`	String class in Arduino.
`unsigned char`	Unsigned 8-bit character data type.
`unsigned int`	Unsigned integer data type.
`unsigned long`	Unsigned long integer data type.
`void`	Represents the absence of a type.
`word`	16-bit unsigned data type.

Variable Scope & Qualifiers

Method & Parameter	Description
`const`	Qualifier to define constants.
`scope`	Not a specific keyword; refers to variable scope.
`static`	Qualifier to declare static variables.
`volatile`	Qualifier to declare volatile variables.

Utilities

Method & Parameter	Description
`PROGMEM`	Qualifier to store data in program memory.
`sizeof()`	Operator to determine the size of a data type or variable.

Structure

Sketch

Method & Parameter	Description
`void loop()`	Main function for continuous code execution.
`void setup()`	Initialization function, called once at startup.

Control Structure

Method & Parameter	Description
`break`	Exits a loop or switch statement.
`continue`	Skips the rest of a loop iteration.
`do...while`	Executes a block of code repeatedly while a specified condition is true.
`else`	Part of the if-else statement.
`for`	Creates a loop with a specified initialization, condition, and increment.
`goto`	Transfers control to a labeled statement.
`if`	Conditional statement for decision-making.
`return`	Exits a function and optionally returns a value.
`switch...case`	Multi-way branch statement.
`while`	Creates a loop with a specified condition.

Further Syntax

Method & Parameter	Description
`#define (define)`	Macro definition for code substitution.
`#include (include)`	Includes a file in the source code.
`/* */ (block comment)`	Block comment for multiple lines.
`// (single line comment)`	Single line comment.
`; (semicolon)`	Statement terminator.
`{} (curly braces)`	Block of code, often used with control structures.

Arithmetic Operators

Method & Parameter	Description
`% (remainder)`	Modulo operator for finding the remainder of a division.
`* (multiplication)`	Multiplication operator.
`+ (addition)`	Addition operator.
`- (subtraction)`	Subtraction operator.
`/ (division)`	Division operator.
`= (assignment operator)`	Assignment operator.

Comparison Operators

Method & Parameter	Description
`!= (not equal to)`	Checks if two values are not equal.
`< (less than)`	Checks if the left value is less than the right value.
`<= (less than or equal to)`	Checks if the left value is less than or equal to the right value.
`== (equal to)`	Checks if two values are equal.
`> (greater than)`	Checks if the left value is greater than the right value.
`>= (greater than or equal to)`	Checks if the left value is greater than or equal to the right value.

Boolean Operators

Method & Parameter	Description
`! (logical not)`	Inverts the logical value, true becomes false and vice versa.
`&& (logical and)`	Logical AND operator, returns true if both operands are true.
`\|\| (logical or)`	Logical OR operator, returns true if at least one operand is true.

Pointer Access Operators

Method & Parameter	Description
`& (reference operator)`	Returns the memory address of a variable.
`* (dereference operator)`	Accesses the value pointed to by a pointer.

Bitwise Operators

Method & Parameter	Description
`& (bitwise and)`	Performs bitwise AND operation.
`<< (bitshift left)`	Shifts bits to the left.
`>> (bitshift right)`	Shifts bits to the right.
`^ (bitwise xor)`	Performs bitwise XOR (exclusive OR) operation.
`\| (bitwise or)`	Performs bitwise OR operation.
`~ (bitwise not)`	Inverts all bits.

Compound Operators

Method & Parameter	Description
`%= (compound remainder)`	Performs a modulo operation and assigns the result to the left operand.
`&= (compound bitwise and)`	Performs a bitwise AND operation and assigns the result to the left operand.
`*= (compound multiplication)`	Multiplies the left operand by the right operand and assigns the result to the left operand.
`++ (increment)`	Increments the value of the operand by 1.
`+= (compound addition)`	Adds the right operand to the left operand and assigns the result to the left operand.
`-- (decrement)`	Decrements the value of the operand by 1.
`-= (compound subtraction)`	Subtracts the right operand from the left operand and assigns the result to the left operand.
`/= (compound division)`	Divides the left operand by the right operand and assigns the result to the left operand.
`^= (compound bitwise xor)`	Performs a bitwise XOR operation and assigns the result to the left operand.
`\|= (compound bitwise or)`	Performs a bitwise OR operation and assigns the result to the left operand.

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reference.md

reference.md

Functions

Digital I/O

Analog I/O

Advanced I/O

Time

Math

Trigonometry

Characters

Random Numbers

Bits and Bytes

External Interrupts

Interrupts

Stream

Serial

SPI

I2C (Wire)

Variables

Enums

Conversion

Data Types

Variable Scope & Qualifiers

Utilities

Structure

Sketch

Control Structure

Further Syntax

Arithmetic Operators

Comparison Operators

Boolean Operators

Pointer Access Operators

Bitwise Operators

Compound Operators

Files

reference.md

Latest commit

History

reference.md

File metadata and controls

Functions

Digital I/O

Analog I/O

Advanced I/O

Time

Math

Trigonometry

Characters

Random Numbers

Bits and Bytes

External Interrupts

Interrupts

Stream

Serial

SPI

I2C (Wire)

Variables

Enums

Conversion

Data Types

Variable Scope & Qualifiers

Utilities

Structure

Sketch

Control Structure

Further Syntax

Arithmetic Operators

Comparison Operators

Boolean Operators

Pointer Access Operators

Bitwise Operators

Compound Operators