Arduino Programming Quick Guide

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This is a handy Arduino programming guide for those who already have some experience with Arduino but sometimes forget about the basics.

Structure

void setup()

void loop()

 

Control Structures

if (x<5){ } else { }

switch (myvar) {

case 1:

break;

case 2:

break;

default:

}

for (int i=0; i <= 255; i++){ }

while (x<5){ }

do { } while (x<5);

continue; //Go to next in do/for/while loop

return x; // Or ‘return;’ for voids.

goto // not encouraged

 

Further Syntax

// (single line comment)

/* (multi-line comment) */

#define DOZEN 12 //Not baker’s!

#include <avr/pgmspace.h>

 

General Operators

= (assignment operator)

+ (addition)

– (subtraction)

* (multiplication)

/ (division)

% (modulo)

== (equal to) != (not equal to)

< (less than) > (greater than)

<= (less than or equal to)

= (greater than or equal to)

&& (and) II (or) ! (not)

 

Pointer Access

& reference operator

* dereference operator

Bitwise Operators

& (bitwise and) I (bitwise or)

^ (bitwise xor) ~ (bitwise not)

« (bitshift left) » (bitshift right)

 

Compound Operators

++ (increment) — (decrement)

+= (compound addition)

-= (compound subtraction)

*= (compound multiplication)

/= (compound division)

&= (compound bitwise and)

|= (compound bitwise or)

 

Constants

HIGH I LOW

INPUT I OUTPUT

true I false

143 // Decimal number

0173 // Octal number

0b11011111 //Binary

Ox7B // Hex number

7U // Force unsigned

10L // Force long

15UL // Force long unsigned

10.0 // Forces floating point

2.4e5 // 240000

 

Data Types

void

boolean (0, 1, false, true)

char (e.g. ‘a’ -128 to 127)

unsigned char (0 to 255)

byte (0 to 255)

int (-32,768 to 32,767)

unsigned int (0 to 65535)

word (0 to 655word (0 to 65535)

long (-2,147,483,648 to 2,147,483,647)

unsigned long (0 to 4,294,967,295)

float (-3.4028235E+38 to 3.4028235E+38)

double (currently same as float)

sizeof(myint) // returns 2 bytes

 

Strings

char S1[15];

char S2[8]={‘a’,’r’,’d’,’u’,’i’,’n’,’o’};

char S3[8]={‘a’,’r’,’d’,’u’,’i’,’n’,’o’, ‘\0’};

//Included \0 null termination

char S4[ ] = “arduino”;

char S5[8] = “arduino”;

char S6[15] = “arduino”;

 

Arrays

int mylnts[6];

int myPins[] = {2, 4, 8, 3, 6};

int mySensVals[6] = {2, 4, -8, 3, 2};

 

Conversion

char()        byte()

int()        word()

long()        float()

 

Qualifiers

static // persists between calls

volatile // use RAM (nice for ISR)

const // make read-only

PROGMEM // use flash

 

Digital I/O

pinMode(pin, [INPUT,OUTPUT])

digitalWrite(pin, value)

int digitalRead(pin)

//Write High to inputs to use pull-up res

 

Analog I/O

analogReference([DEFAULT, INTERNAL, EXTERNAL])

int analogRead(pin) //Call twice if switching pins from high Z source.

analogWrite(pin, value) // PWM

 

Advanced I/O

tone(pin, freqhz)

tone(pin, freqhz ,duration_ms)

noTone(pin)

shiftOut(dataPin, clockPin, [MSBFIRST,LSBFIRST], value)

unsigned long pulseln(pin,[HIGH,LOW])

 

Time

unsigned long millis() // 50 days overflow.

unsigned long micros() //70 min overflow

delay(ms)

delayMicroseconds(us)

 

Math

min(x, y) max(x, y) abs(x)

constrain(x, minval, maxval)

map(val, fromL, fromH, toL, toH)

pow(base, exponent) sqrt(x)

sin(rad) cos(rad) tan(rad)

 

Random Numbers

randomSeed(seed) // Long or int

long random(max)

long random(min, max)

 

Bits and Bytes

lowByte()

highByte()

bitRead(x,bitn)

bitWrite(x,bitn,bit)

bitSet(x,bitn)

bitClear(x,bitn)

bit(bitn) //bitn: 0-LSB 7-MSB

 

External Interrupts

attachlnterrupt(interrupt, function, [LOW,CHANGE,RISING,FALLING])

detachInterrupt(interrupt)

interrupts()

nolnterrupts()

 

Serial.

begin([300, 1200, 2400, 4800, 9600,14400, 19200, 28800, 38400, 57600,115200])

end()

int available()

int read()

flush()

print()

println()

write()

 

EEPROM (#include <EEPROM.h>)

byte read(intAddr)

write(intAddr,myByte)

 

Servo (#include <Servo.h>)

attach(pin , [min_uS, max_uS])

write(angle) // 0-180

writeMicroseconds(uS) 111000- 2000,1500 is midpoint

read() // 0-180

attached() //Returns boolean

detach()

 

SoftwareSerial(RxPin,TxPin)

// #include<SoftwareSerial.h>

begin(longSpeed) // up to 9600

char read() // blocks till data

print(myData) or println(myData)

 

Wire (#include <Wire.h>) // For I2C

begin() // Join as master

begin(addr) // Join as slave @ addr

requestFrom(address, count)

beginTransmission(addr) // Step 1

send(mybyte) // Step 2

send(char * mystring)

send(byte * data, size)

endTransmission() // Step 3

byte available() // Num of bytes

byte receive() //Return next byte

onReceive(handler)

onRequest(handler)