Basic Library

Digital I/O
Analog I/O
Advanced I/O
Time
Math
Trigonometry
Random Numbers
Bits and Bytes
Interrupts
Serial Comm.

Standard Library

Ethernet
Servo Motor
Stepping Motor
Character LCD
SPI
I2C (Wire)
SD Card
SD (File Operations)
Periodic Operation
Clock (RTC)
PPG (Pulse Generator)
WiFiEsp
ICS (Serial Servo)

FreeRTOS Tips

Overview
Task
Queue
Timer
Interrupt Management

Math

This library performs all types of calculations including min/max, absolute value and the square root of a number. Users can also constrain a number within a range, re-map a number from one range to another, and calculate the value of a number raised to a power.

min

Description
Compares two values, returns the smaller one.
Syntax
min(x, y)
Parameters
x: The first number, any data type
y: The second number, any data type
Returns
The smaller of the two parameter values.

max

Description
Compares two values, returns the larger one.
Syntax
max(x, y)
Parameters
x: The first number, any data type
y: The second number, any data type
Returns
The larger of the two parameter values.

abs

Description
Computes and returns the absolute value of a number.
Syntax
abs(x)
Parameters
x: The number to be converted
Returns
If x is greater than or equal to 0, returns x; if less than than 0, returns -x.

constrain

Description
Constrains a number to be within a range.
Syntax
constrain(x, a, b)
Parameters
x: The number to constrain, all data types
a: The lower end of the range, all data types
b: The upper end of the range, all data types
Returns
If x is between a and b, returns x; if x is less than a, returns a; if x is greater than b, returns b.

map

Description
Re-maps a number from one range to another. For example, when the value is 5 within the range of 0 to 10, it is re-mapped to 50 in the range of 0 to 100.
Syntax
map(value, fromLow, fromHigh, toLow, toHigh)
Parameters
value: The number to map
fromLow: The lower bound of the value's current range
fromHigh: The upper bound of the value's current range
toLow: The lower bound of the value's target range
toHigh: The upper bound of the value's target range
Returns
The value after mapping

pow

Description
Calculates power (exponential).
Syntax
pow(base, exponent)
Parameters
base: Any value; (float)
exponent: The power to which the base is raised (float)
Returns
The result of the exponentiation (double)

sqrt

Description
Calculates the square root of a number.
Syntax
sqrt(x)
Parameters
x: The number, any value
Returns
Double, the number's square root.

Sample Program

Sample using constrain and pow.


#include <Arduino.h>
void setup(){
    Serial.begin(9600);
}
 
void loop(){
    Serial.println("Calculate the area of a circle ");
    Serial.println("Input value 0-9");
    while(!Serial.available());
     
    int d = Serial.read();
     
    d = constrain(d - 0x30, 0, 9); //convert from ASCII to numeric, and remove error value
    Serial.print(d);
    Serial.print(" x ");
    Serial.print(d);
    Serial.print(" x 3.14 = ");
 
    Serial.println(pow(d, 2) * PI);
}