Arduino - HardwareSome Points to Remember

ICSP

LED14 (POWER)

JP4

0 0 0

D2

D3

D1

1 2 3 4 5

ANALOG INDC1

LED1(Rx)

LED0(Tx)C1 C2 C3

R3

R2

R1

R4

R5

R6

R7 R8

AR

EF 0V 13 12 11 10 9 8 7 6 5 4 3 2 1 0

PWM (PWM-AT168)

T1

T2

C7C6

C8

PIN 13

9V5VNC

RST

SCL

SDA

POWER

C5

L1

S1

R9

R10

R11

C9

JP0

TX

RX

SERIAL ENABLE

PIN 0/1 GND REF

PIN 2(TxD)

PIN 3(RxD)

PIN 4(DSR)

PIN 5(GND)

16MHz

AU

TO R

ESET

C4

MISO SV

MOSI

GND

SCK

RST

12VGND

RESET

Points to remember

• When talking about pins on arduino, it is never ic pins but pins on connector as marked. (refer to previous sheet to see mapping)

• Arduino has totally 20 I/O pins

• Out of which six are dedicated for Analog

• Pins 0 to13 are digital 0 to 13 and written on the board.

• Analog pins are 0 to 5 and written on the board.

• They are also accessed as digital 14 to 19 (not written on the board)

Points to remember

• Pin 0 is also used as RX and 1 as TX. So if using serial port, use 0 and 1 for RX and TX.

• Analog 4 and 5 (or digital 18 and 19) are SCL and SDA. When using I2C ics use these pins.

• Pin13 is on board LED.

• For Ananlog input use ANALOG 0 to 5.

• Pin 8, 10 and 11 are PWM and is used for dimmable LED or creating analog voltage. Pin 3,5,6 are also PWM and are found only in ATMEGA 48/ 88 / 168.

Points to remeber

• So when starting a new board, first allocate analog inputs, rx, tx, scl, sda, led and PWM as these signals can only be used on certain pins.

• Then use rest of the pins as general purpose I/O pins.

• Unused signals (say ANALOG inputs or PWM) can be used for general purpose digital I/O pins.

• Digital pins 11,12,13 are used for programming. Take care and do not connect and low impedence load or any other output.