Build Your Own Arduino

Step 4 Component Hook Up

To start, we will build the supporting circuitry for one side of the chip and then move on to the other side. Pin one on most chips has an identifier marker. Looking at the ATmega168 or 328 you will notice a u-shaped notch at the top as well as a small dot. The small dot indicates that this is pin 1.

 

Figure 1-6: Supporting circuitry pins 15-28

 

From the GND power bus, add a jumper wire to pin 22. Next, from the positive power bus, add jumper wires to pin 20 (AVCC - Supply voltage for the ADC converter. Needs to be connected to power if ADC isn't being used and to power via a low-pass filter if it is (a low pass filter is a circuit that cleans out noise from the power source, we aren't using one)

Then add a jumper wire from the positive bus to pin 21 (Analog reference pin for ADC).

 

On the Arduino, pin 13 is the LED pin. Note that on the actual chip the pin is number 19. When uploading your sketch code and for all projects you will still reference this as Pin 13.

 

To hook up the LED, add a 220& resistor from GND to the cathode of the LED. Then from the anode of the LED add a jumper wire to pin 19.

 

Now we can move onto the other side of the chip. You are almost finished!

Figure 1-7: Supporting circuitry pins 1-14

 

Above the ATmega168 chip near the pin 1 identifier, place the small tact switch. This switch is used for resetting the Arduino. Right before you upload a new sketch to the chip you will want to press this once. Now add a small jumper wire from pin 1 to the bottom leg of the switch then add the 10K resistor from power to the pin 1 row on the breadboard. Finally add a GND jumper wire to the top leg of the switch.

 

Add power and GND jumpers to pin 7(VCC) and pin 8 (GND). Add the 16MHz clock crystal to pin 9 and 10 and then the two .22pF capacitors from pins 9 and 10 to GND. (See note below for alternative method).

 

Your basic breadboard arduino is now complete. You could stop right here if you wanted to and swap an already programmed chip from your Arduino board to the breadboard, but since you came this far, you might as well finish off by adding some programming pins. This will allow you to program the chip from the breadboard.

 

NOTE: Instead of using the 16MHz clock crystal, you can use a 16 MHz ceramic resonator with built-in capacitors, three-terminal SIP package. You will have to arrange your breadboard a little differently, the resonator has three legs. The middle leg will go to ground and the other two legs will go to pins 9 & 10 on the ATmega168 chip.

 
Referring to Figure 1-7, locate a spot where you have 6 columns on the breadboard that are not in contact with anything else. Place a row of six male header pins here.

 

With the breadboard facing you, the connections are as follows:

GND, NC, 5V, TX, RX, NC, I am also calling these pins 1,2,3,4,5,6. From your power bus rail, add the GND wire to pin 1 and a wire from power for pin 3. NC means not connected, but you can connect these to GND if you want to.

 

From pin 2 on the ATmega168 chip, which is the Arduino RX pin, you will connect a wire to pin 4 (TX) of your programming headers. On the ATmega168 chip, pin 3 Arduino TX gets connected to pin 5 (RX) on your header pins.

 

The communication looks like this: ATmega168 RX to Header Pin TX, and ATmega168 TX to Header Pin RX.

 

Now you can program your breadboard Arduino.