In this article, I will show you how to make your own AVR development board for ATmega8 microcontroller.

What is a development board?

In order to learn any MCU like AVR we need a AVR MCU that has all the basic connections like power supply, crystal oscillator, proper reset signal and an ISP connector for uploading a program. All these things are required for any project you will make. A development board is a circuit board that contains all these connections and it has connectors for IO pins of MCU so that they can be connected to any external circuit with ease. So as you see its is like a basic framework. Once you make a good development board and test it, you will have a solid foundation and for your project you can concentrate on the specific requirement of that project. This will also reduce the chance of making errors.

Some more complicated development boards have a RS232 level converters(for serial communication) ,motor control chips etc.

Now let’s do it!

I have described the basic connections required by any AVR MCU in
Part III of my AVR tutorial series
so I am jumping right to the schematic.

atmega8 basic schematic circuit

Fig – Development board schematic.

Things you need are

S.No Components Name Value
01
ATmega8 IC1  
02
Voltage Regulator IC7805 IC2  
03
Resistance R1
330ohm
04
Resistance R2
1k
05
Capacitor(Electrolytic/Polar) C1
100uF
06
Capacitor(Electrolytic/Polar) C2
100uF
07
Capacitor(Electrolytic/Polar) C6
1uF
08
Capacitor(Ceramic disk type) C3
0.1uF
09
Capacitor(Ceramic disk type) C4
22pF
10
Capacitor(Ceramic disk type) C5
22pF
11
Capacitor(Ceramic disk type) C6
0.1uF
12
Inductor L1
10uH
13
Diode D1
1N4007
14
Crystal Oscillator Q1
16Mhz
15
LED LED1  
16
Tactile push to on switch S1  
17
Connectors,IC Socket, Power jack, general purpose PCBs, wires etc    

Note: The voltage rating of C1 must be at least twice the
input voltage while that of C2 & C6 can be 12 Volts or more

Components

Fig – Components for power supply

Components

Fig – ATmega8, Resistors, Capacitors and Connectors.

Components

Fig – Veroboard / General purpose PCB – Top View

Components

Fig – Veroboard / General purpose PCB – Bottom View

Components

Fig – Connectors for easy connection/disconnection from MCU pins

 

Now connect the components according to the schematic on a general purpose PCB. You will get something like this.

atmega8 board
simple atmega8 board
atmega8 board

Fig – Final Board with all components assembled.

Before inserting the MCU, first test the board for any connection error. Make sure everything is according to the schematic. Then check for any soldering errors like loose joints or unwanted shorting by solder. Finally connect power supply of 8 to 18 volts to the circuit by using an adaptor, battery, or transformer (after converting to DC). Check the power pins of MCU in the IC socket with a multi-meter for voltage. It should be very close to 5V. If everything is ok your board is ready.

Note

Some difference in my prototype and the schematic.

  1. The value of C2 is 100uF but I have used 0.1uF ceramic type.
  2. I have not used the reverse protection diode D1. But you should for safety.
  3. I have used 220uF capacitor as C1. Anything over 100uF will do. Also the
    voltage rating must be double the input supply voltage
  4. I have not used the reset switch. However, it is very convenient if we
    have one.
  5. I have not used C6(1uF) as it is required for reset switch
  6. I have not used L1 for connecting the AVcc to Vcc, instead I have directly
    connected them. But if you are planning to use the ADC you should use the
    L1 as it makes the ADC much accurate by suppressing noise
  7. I have connected a 0.1uF capacitor from Vref to GND as it is suggested by
    datasheet. Only necessary if you are using ADC.

The same board made with a professional PCB.

A simple ATmega8 Devboard

Fig – A simple ATmega8 Devboard

You can buy it
from here
at only Rs 450/-. Sorry, but currently I ship it only within India
(no International shipping right now).

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