Introduction: Arduino From Evil Mad Scientist ATmegaxx8 Target Board

By laclejeune.ca

I have been making my own Arduino's on strip-board but recently bought some of the Evil Mad Scientist ATmegaxx8 Target Boards.
While they weren't designed as an Arduino board they are perfect to use as they have:
- places for the crystal and capacitors (XTL and C1, C2) or resonator
- place for the power smoothing capacitor (C3 on the board)
- place for the 100nF capacitor across VCC and Gnd, pins 7 & 8 (C4)
- have 4 prototype spaces on the board which can hold 2x 14pin DIP chips
- has 3 holes per Arduino pin to solder leads to
- has bus lines suitable for 5V and ground

In this Instructable I am using 2 of the 4 prototype areas, one for the 5V regulator and one for the FTDI headers.  If you are going to use a 5V supply like a wall wart then you won't need the regulator and if you want to program the AVR chip in a regular Arduino and move it into this board then you won't require the FTDI headers.

For a schematic I base my build on the minimalist Arduino circuit found at thetransistor.com

Step 1: What You Need

ATmegaXX8 Target Board
28 Pin IC socket (or 2x 14 pin)
ATmega328P with Arduino firmware
16 MHz Crystal
2x 22pF capacitors
2x .1uF capacitors
2x 10uF electrolytic capacitors
LM7805 5V regulator
IN4001 diode
6-pin header
100k 1/4w resistor
hookup wire
LED and 220ohm resistor for testing

For a schematic I base my build on the minimalist Arduino circuit found at thetransistor.com

Step 2: Socket

Solder in the IC socket - I used 2x 14 pin sockets for this build.
Notch to the left.

Step 3: Crystal & Caps

Solder in the crystal and 22pF caps
Alternatively you could use a 16MHz resonator instead of the crystal and without the capacitors.

Step 4: 5V Regulator

I am using the top left prototype space for the 5V regulator and caps as it is next to where the C3 is.
There are 7 "buses" and I use the first 4.
Starting on the left will be Vin (from wall wart or batteries), then LM7805 Vin, then GND, then LM7805 Vout (5V)
Between the Vin and LM7805 Vin I put a protection diode (IN4001 or similar)
There are 2x 10uF electrolytic caps used for power smoothing - one goes across the LM7805 Vin and GND, the other goes across LM7805 Vout and ground.  One goes on the prototype area, the other in C3.

Start by jumpering from the GND space to the long bus and over to the 3rd row from the left (1st picture)
Next solder in the diode as shown, stripe to the top (2nd picture)
Next solder in the 2 10uF caps minus to ground (3rd & 4th pictures)
Next jumper between the 4th row and Vcc In, this will take the 5V regulated power and supply it to the board (5th picture)
Next solder in the LM7805 (6th & 7th picture)

Step 5: 5V and GND

Next we need to jumper Vcc (5V)  to pin 20 and GND to pin 22 (1st picture)
Then solder in a .1uF capacitor in C4 (2nd picture).

Step 6: FTDI Header

To upload sketches without removing and re-installing the AVR chip we need to add FTDI pins.
This will enable you to use a USB to FTDI board like this one from SparkFun
I used the second protype area closest to pin 1 of the Ardunio.

Start by soldering in a 6 pin header (1st picture).
The pins shown in the first picture will be L to R: GND, not used, Vcc (5V), TX, RX, DTR/RST
Next jumper from the GND bus to pin 1 of the FTDI header (2nd picture).
Next jumper from Vcc to pin 3 of the FTDI header (3rd or 4th picture).
Next jumper from pin 4 of the FTDI header to pin 2 of the Arduino and pin 5 of the FTDI header to pin 3 of the Arduino (3rd, 4th & 5th pictures)
Next solder in a .1uF capacitor from pin 6 of the FTDI header and pin 1 of the Arduino (3rd & 4th pictures)
Next solder in a 10k ohm 1/4 w resistor between pin 1 of the Arduino and pin 7 of the Arduino (5th picture)

I also jumpered from Vcc to the bus line as shown in picture 6 - this gives me a Vcc (5V) line and a Ground line where I can feed things like LCD displays, servo's etc from.

Step 7: Testing

Use a meter to make sure there are no shorts between  Vcc and GND.

Install the Arduino chip into the socket with the notch facing left.

To test the Arduino via the "blink" sketch connect an LED from digital pin 13 (Arduino pin 19) to ground via a 220 ohm resistor (1st picture)
Plug in your FTDI board and upload the sketch.
If everything is correct you should have a blinking LED.

External power leads should be soldered in as indicated in the 3rd picture - positive lead on the same bus as the diode, the negative lead to GND.
Do not power the board from an external source and the FTDI header at the same time, use one or the other.