Here I will show you how to build a micro controller on a breadboard or a prototyping board.

You may want to do this if you would like to make your project permanent and or smaller.

I have read a few instructions some are easier to understand then others, I will try to make a beginner guide. Something easy to understand.

Step 1: Parts.

Per programed Atmega 328P-PU with bootloader

16mHZ Crystal oscillator

2X 22pF Compactors

10K Resistor

2X 10uf Compactor 16V

Some sort of Voltage regulator (I'll use a 7805CV 5 volt regulator) I will talk more about regulators later...

Breadboard to start and test, Don't forget you will need jumpers or wires for the breadboard. This kit come with both

Prototyping board after testing and to make permanent

Step 2: Lets Look at the Pin Out of the Atmega328P

Pin 1 = for resetting the micro controller.

Pin 2 = Digital pin 0 (RX = receive)

Pin 3 = Digital pin 1 (TX = transmit)

Pin 4 = Digital pin 2

Pin 5 = Digital Pin 3

Pin 6 = Digital pin 4

Pin 7 = VCC (+5VDC)

Pin 8 = GND (Ground)

Pin 9 = Crystal (16mHZ)

Pin 10 = Crystal (16mHZ)

Pin 11 = Digital pin 5

Pin 12 = Digital pin 6

Pin 13 = Digital pin 7

Pin 14 = Digital pin 8

Pin 15 = Digital pin 9

Pin 16 = Digital pin 10

Pin 17 = Digital pin 11

Pin 18 = Digital pin 12

Pin 19 = Digital pin 13

Pin 20 = VCC (+5VDC)

Pin 21 = Analog Reference (+5VDC)

Pin 22 = GND (Ground)

Pin 23 = Analog input 0

Pin 24 = Analog input 1

Pin 25 = Analog input 2

Pin 26 = Analog input 3

Pin 27 = Analog input 4

Pin 28 = Analog input 5

Step 3: Schematic for You Breadboard

Start by inserting you Atmega 328P in to the breadboard

Then connect the crystal to Pins 9 and 10

Then add you 22pF capacitors to pin 9 and ground and another one the pin 10 and ground

Then connect Pins 8 and 21 to ground

Then Connect Pin 8 20 and 21 to +5VDC

Than connect Pin 1 to a 10K resistor and to +5VDC

Next step we will work on the Power regulator to power the Atmega 328P

Step 4: Regulators...

Different types of regulators

  1. 5 volt regulator like the 7805CV

  2. Variable regulators like a LM317
  3. Buck Converter or Step-Down Converter

Lets talk about a 7805CV Datasheet

The 7805CV Will take a + voltage from +5VDC to +18VDC and convert it to +5VDC


input voltage can vary and you will still have +5VDC on the output as long as the input voltage doesn't drop below +5VDC. Will work will with battery's


Gives off heat. If you have you circuit in a small enclosed space you may over heat the 7805CV and cause it to turn off.

The LM317 Datasheet

The LM317 Will take + voltage from +1.25DC to +37VDC. You will need at lest +9VDC to convert it to +5VDC.


Cheaper then a 7805CV. Would work best with a AC to DC adapter


You will always need a steady in put voltage if your input voltage drops your output voltage will drop. Gives off heat. If you have you circuit in a small enclosed space you may over heat the 7805CV and cause it to turn off.

A Buck converter

Will take a wide variety of in put voltage and out put +5VDC.


Unlike the LM317 you can put +5VDC in and still get +5VDC out but if the input voltage drops your output voltage will also drop. The most energy efficient. When ever you create heat you are loosing energy. If your input Voltage drops you can adjust the potentiometer (variable resistor) to increase your output voltage until your input voltage drops below +5VDC.


Like a 7805CV You will need a steady in put voltage if your input voltage drops your output voltage will drop. Most expensive.

Step 5: 7805CV

Page 3 of the Datasheet will show you the pin out of the mosfet

from left to right

Pin 1 = input voltage (=5VDC to +18VDC)

Pin 2 = Ground (from input and to output)

Pin 3 = Output voltage (+5VDC)

Connect a 10uf capacitor to Pin 1 and Pin 2

Also connect a 10uf Capacitor to Pin 2 and Pin 3

<p>Hi robmawe91.<br>You have a small error in step 23 with your connections. It should read as follow:<br>- Then connect Pins 8 and 22 to ground</p><p>- Then Connect Pin 7 and 20 to +5VDC</p><p>! ! ! VERY IMPORTANT ! ! !<br>Do NOT connect pin 21 to +5V or 0V. </p><p>When using analoqReference(DEFAULT), this pin will measure the same as the supply voltage to the 328 chip. This is the default setting of the Arduino.</p><p><br>When using analogReference(INTERNAL), this pin will measure 1.1 volt. If this pin is also connected to +5V, the A/D converter will not work correct, and the 328 chip might get damaged.<br><br>Have a look at the internal diagram of the A/D converter inputs.</p>
<p>Thank you Eric, This is just how I have seen it done many times. I have also built many things with the Atmega 328P and have wired it up with the AREF to +5V. I will take this into consideration next time I build something. Thank you! </p>

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