Control Structures
if (x < 5) { ... } else { ... }
while (x < 5) { ... }
do { ... } while ( x < 5);
for (int i = 0; i < 10; i++) { ... }
break; // exit a loop immediately
continue; // go to next iteration
switch (myVar) {
case 1:
...
break;
case 2:
...
break;
default:
...
}
return x; // just return; for voids
Basic Program Structure
void setup() {
// runs once when sketch starts
}
void loop() {
// runs repeatedly
}
General Operators
= (assignment operator)
+ (add) - (subtract)
* (multiply) / (divide)
% (modulo)
== (equal to) != (not equal to)
< (less than) > (greater than)
<= (less than or equal to)
>= (greater than or equal to)
&& (and) || (or) ! (not)
Pointer Access
& (reference: get a pointer)
* (dereference: follow a pointer)
Bitwise Operators
& (bitwise and) | (bitwise or)
^ (bitwise xor) ~ (bitwise not)
<< (shift left) >> (shift right)
Compound Operators
++ (increment)
-- (decrement)
+= (compound addition)
-= (compound substraction)
*= (compound multiplication)
/= (compound division)
&= (compound bitwise and)
|= (compound bitwise or)
Constants
HIGH | LOW
INPUT | OUTPUT
true | false
143 (Decimal)
0173 (Octal - base 8)
0b11011111 (Binary)
0x7B (Hexadecimal - base 16)
7U (force unsigned)
10L (force long)
15UL (force long unsigned)
10.0 (force floating point)
2.4e5 (2.4*10^5 = 240000)
Data types
void
boolean (0, 1, true, false)
char (e.g. 'a' -128 to 127)
int (-32768 to 32767)
long (-2147483648 to 2147483647)
unsigned char (0 to 255)
byte (0 to 255)
unsigned int (0 to 65535)
word (0 to 65535)
unsigned long (0 to 4294967295)
float (-3.4028e+38 to 3.4028e+38)
double (currently same as float)
Strings
char S1[8] =
{'A','r','d','u','i','n','o'};
// unterminated string; may crash
char S2[8] =
{'A','r','d','u','i','n','o','\0'};
// includes \0 null termination
char S3[]="Arduino";
char S4[8]="Arduino";
Arrays
int myInts[6]; // array of 6 ints
int myPins[]={2, 4, 8, 3, 6};
int mySensVals[6]={2, 4, -8, 3, 2};
myInts[0]=42; // assigning first
// index of myInts
myInts[6]=12; // ERROR! Indexes
// are 0 though 5
Type Conversions
char() byte()
int() word()
long() float()
Qualifiers
static (persists between calls)
volatile (in RAM (nice for ISR))
const (make read only)
PROGMEM (in flash)
Pin Input/Output
Digital I/O (pins: 0-13 A0-A5)
pinMode(pin,[INPUT, OUTPUT])
int digitalread(pin)
digitalWrite(pin, value)
// Write HIGH to an input to
// enable pull-up resistors
Analog In (pins: 0-5)
int analogRead(pin)
analogReference(
[DEFAULT, INTERNAL, EXTERNAL])
PWM Out (pins: 3 5 6 9 10 11)
analogWrite(pin, value)
Advanced I/O
tone(pin, freqhz)
tone(pin, freqhz, duration_ms)
noTone(pin)
shiftOut(dataPin, clockPin,
[MSBFIRST,LSBFIRST], value)
unsigned long pulseIn(pin,
[HIGH,LOW])
Time
unsigned long millis()
// overflows at 50 days
unsigned long micros()
// overflows at 70 minutes
delay(msec)
delayMicroseconds(usec)
Math
min(x, y) max(x, y) abs(x)
sin(rad) cos(rad) tan(rad)
sqrt(x) pow(base, exponent)
constrain(x, minval, maxval)
map(val, fromL, fromH, toL, toH)
Random Numbers
randomSeed(seed) // long or int
long random(max)
long random(min, max)
Bits and Bytes
lowByte(x) highByte(x)
bitRead(x, bitn)
bitWrite(x, bitn, bit)
bitSet(x, bitn)
bitClear(x, bitn)
bit(bitn) // bitn: 0=LSB 7=MSB
External Interrupts
attachInterrupt(interrupt, func,
[LOW, CHANGE, RISING, FALLING])
detachInterrupt(interrupt)
interrupts()
noInterrupts()
Serial (communicate with PC or via RX/TX)
begin(long Speed) // up to 115200
end()
int available() // #bytes available
byte read() // -1 if none available
byte peek()
flush()
print(myData)
println(myData)
write(myBytes)
SerialEvent() // called if data rdy
EEPROM (#include <EEPROM.h>)
byte read(intAddr)
write(intAddr, myByte)
Servo (#include <Servo.h>)
attach(pin, [min_uS, max_uS])
write(angle) // 0 to 180
writeMicroseconds(uS)
// 1000-2000; 1500 is midpoint
int read() // 0 to 180
bool attached()
detach()
SoftwareSerial (serial comm. on any pins)
(#include <softwareSerial.h>)
SoftwareSerial(rxPin, txPin)
begin(long Speed) // up to 115200
listen() // Only 1 can listen
isListening() // at a time.
read, peek, print, println, write
// all like in Serial library
Wire (I²C comm.) (#include <Wire.h>)
begin() // join a master
begin(addr) // join a slave @ addr
requestFrom(address, count)
beginTransmission(addr) // Step 1
send(myByte) // Step 2
send(char * mystring)
send(byte * data, size)
endTransmission() // Step 3
int available() // #bytes available
byte receive() // get next byte
onReceive(handler)
onRequest(handler)
Libraries
Arduino Programming Cheat Sheet Primary source: Arduino Language Reference
http://arduino.cc/en/Reference/
by Mark Liffiton
Structure & Flow Operators Built-in Functions
Variables, Arrays, and Data
Adapted from:
- Original by Gavin Smith
- SVG version by Frederic Dufourg
- Arduino board drawing
original by Fritzing.org
DIGITAL (PWM~)
AREF
GND
13
12
~11
~10
~9
8
7
~6
~5
4
~3
2
TX→1
RX←0
L
TX
RX
POWER ANALOG IN
A0
A1
A2
A3
A4
A5
IOREF
RESET
3.3V
5V
GND
GND
Vin
ON
WWW.ARDUINO.CC - Made in Italy
RESET
ICSP
1
int1
int0
SDA
SCL
SCL
SDA
DC in
sugg. 7-12V
limit 6-20V
ATmega382:
16MHz, 32KB Flash (prog.),
2KB SRAM, 1KB EEPROM
ARDUINO UNO
