AVR Development board, Step-by-Step-Tutorial

How to build an Atmega8 development board


Insert a Push button Switch

Insert a six pin push button switch (an On/Off switch) to the bottom of the board. Also add a two pin header in the same column as the power and ground lines of left headers.

Insert DIP switch DIP_switch_schematic

This Switch has six pins which can connect two inputs and outputs. Be careful while inserting the switch as inserting the wrong way may mess up your board. Affix two more red wires; one from power line of battery header to the switch and the other one from switch to another header pin. This switch is used to separate the power lines from left headers to right headers. Once pressed, it connects battery power across both sides of the board. In case you wish to add different source (for motors and servos) then you can add another battery to left header which powers left side of the board.

Add connections to switch

Solder the wires together as shown. The top two pins and the middle two pins of the switch are connected. If the switch is pressed, it shorts the two lines connecting the two battery headers.

The bottom two pins are left unconnected and you can solder those pins to the board to hold it stiff.

Solder DIP switch DIP_switch_conn

Add one more black wire directly from left header ground to right header ground.

Add ground line to connect both sides

Solder the wire to the headers.  The black wire is not connected through the switch as we need the ground lines to be common across the board.

Solder ground lines DIP_switch ground

Lastly, connect two more wires, a red and another black wire which connects left headers and left battery header.

Insert two more wires

Solder the wires to the headers as shown in the image.

Solder to connect two sides of board Power to left side

This completes the first phase of the board and you have a complete working board ready. In the next section we will add a reset switch to our board.

Reset Switch

We will now add a reset switch to the circuit. In some situations you would need to reset your program without actually pulling off power. A reset switch is a push button switch which resets your circuit when pressed for certain duration. Generally this is available as a two lead switch and if you not lucky enough and find a two pin switch, just check which shorts the leads in the four lead switch and connect accordingly.

Plug the reset switch such that one lead is close to Pin-1 of the microcontroller and the other with a gap of two pins as shown in the image.

Insert reset switch

Solder the reset switch lead to pin-1 of the microcontroller. The other pin will be connected to ground, but do not solder it for now.

Solder one pin of reset switchreset_switch_avr_dev_board

We will also add a status LED to the board which is useful to check if the circuit is powered on. A current limiting resistor (yes, a normal resistor) of value 330Ω is connected in series with the LED. I have selected a 3mm green LED and you are free to select your favorite color.

Insert LED and Resistorschematic_led_res

LED has a positive and a negative side. The shorter lead indicates ground, and the longer lead goes to power. Insert the LED such that the ground line is in the same column as the ground line of the header and the longer lead (positive side) is in the same column as the Vcc line of the header (left headers).

One lead of the resistor is plugged into a grid available next to the LED (+ve side) while the other lead of the resistor is plugged into power line of the right headers (refer image).

Connect resistor and status led

Now follow these steps carefully:

Solder the leadscomplete atmega8 dev board schematic

Congratulations!!! You are done with an Atmega8 development board. Connect your battery to the board and see the green LED light up. Plug in your Atmega8 microcontroller and start programming.
Note: The new microcontroller might resist getting into the socket; you might have to slightly bend the leads and push it in. Be careful not to break the microcontroller pins.


Tutorial index:

  1. Introduction to AVR Board and Parts required
  2. Building the board- Part I
  3. Building the board- Part II
  4. Building the board- Part III
  5. Building the board- Part IV
  6. Adding LCD header (Optional)

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