7

FORGE

The standalone Arduino can work with just the

16MHz crystal oscillator and the two 22 pF capacitors.

However, using a voltage regulator in your circuit

is highly recommended, as any voltage higher

than 5 V could damage the chip. This circuit can be

implemented on breadboard, protoboard, or a PCB.

You can add all the extra connections that your

project needs in the same way as you would

connect them to an Arduino Uno. The datasheet

(hsmag.cc/exdrFL) for the chip gives details of which

physical pins relate to which internal pins, as well as

other information such as the voltage and current

tolerances. The internal pins are split into three banks:

PB, PC, and PD. PD is digital pins 0–7, PB is digital pins

8–13, and PC is analogue pins 0–5.

Now, go out and shrink down your projects, but

don’t forget to let us know what you create.

YOU’LL NEED

ATmega328P

chip (with or

without bootloader)

16MHz clock

crystal

2 × 22 pF

capacitors

Arduino/Genuino

Uno

Jumper cables

ARDUINO UNO

PIN (WITHOUT CHIP)

ATMEGA328P

CHIP PIN

5 V 7, 20

GND 8, 22

RESET 1

Rx 2

Tx 3

ISP

What is ISP?

ISP stands for

‘In-circuit Serial

Programmer’,

and it’s a

device that

can program

the flash

memory of the

microcontroller,

being connected

to some of

its pins. In

this case, the

Arduino Uno

acts as the ISP.

FLASH

1

1

5

5

10

10

15

15

20

20

25

25

30

30

35

35

40

40

45

45

50

50

55

55

60

60

AB AB

C C

DE DE

F F

GH GH

IJ IJ

1312111098 765432

L

5V A0

ANALOG IN

AREF

1

GND

TX

RX

RESET3V3 GNDGNDVIN A1A2A3A4A5

DIGITAL (PWM= )

Arduino TM

IOREF

ICSP

ICSP2

ON

POWER

10

RESET TX0RX0

ATMEGA328

the main chip on the Uno, we first need to carefully
remove the latter. There’s one large chip in the middle
that’s pushed into place and can be removed by
pulling. It may take a little force, but be careful not to
damage the chip.
Reconnect the Arduino Uno with the standalone
Arduino according to Table 2.
You will upload the code to the standalone Arduino
chip from the Arduino IDE as usual (Sketch > Upload,
or simply clicking on the Upload button). Now you can
disconnect the Arduino Uno, put its chip back, and
reuse the board for your next project.

BOOTING UP

What is a bootloader? It’s a piece of code that runs

in the chip as soon as it is turned on (like the BIOS on

your computer). If the user is trying to program the

chip (with a computer), the bootloader will upload

the program to the chip memory. This enables you to

program the chip through the serial port, just with a

USB cable.

Below

Test your chip with

this circuit and the

Blink sketch

Above

Programming the

ATmega328P chip

Table 2

The connections for programming the ATmega328P

• 
  

• 
  

10 mF 10 mF 22 pF

22 pF

LM7805

20(AVCC)

7 (VCC)

22(GND)

9(PB6)

10(PB7)

8(GND)

19

(PB5)

330 Ω

ATmega328P