Yet Another Daft Punk Coffee Table (5x5 LED Matrix)

Step 8 Costing Down

While using an Arduino is convenient for development/prototyping, it's not a very cost effective way to go once your project is done.  Also, the board is rather bulky.  After initial development, I swapped out the Arduino Duemilanove for a tiny ATmega pcb kit from allgaiershops for $2.99, and a bare ATmega328P from Sparkfun for $4.30.   This board is fully Arduino compatible if you have a USB->Serial converter cable or a hardware AVR programmer.  I have a clone of Adafruit's USBtinyISP.

To program this board using the Arduino IDE, plug your programmer into the ICSP header.  The USBtinyISP supplies 5V power, so not other connection is needed to program and test it.  You will need to make some minor tweaks to your Arduino IDE in order to make it play nicely with the USBtinyISP.  I have posted detailed instructions on my blog:  How to Use the Arduino IDE with an External Programmer.

The next complication is that you need to figure out which pins on your ATmega328P MCU map to the digital pins on the Arduino.  The pin mappings can be found on the Arduino website:  ATmega8-Arduino Pin Mapping
Someone also made a PDF which you can use to print labels to attach directly to your ATmega328P here: Arduino Breadboard Labels .  Here is the specific pin mapping we need for our project:

Arduino Digital Pin  -> ATmega328P pin:
digital pin 12 -> ATmega pin 18
digital pin 11 -> ATmega pin 17
digital pin 10 -> ATmega pin 16
digital pin 9 -> ATmega pin 15
digital pin 8 -> ATmega pin 14
digital pin 7 -> ATmega pin 13
digital pin 6 -> ATmega pin 12
digital pin 5 -> ATmega pin 11
digital pin 4 -> ATmega pin 6
digital pin 3 ->ATmega pin 5
analog pin 0->ATmega pin 23

So take the pin that was connected to digital pin 12 on the Arduino, and connect it to pin 18 on the breadboard, and so on.

A cheap way to power the project once you're done building it is to buy a cheap USB wall wart, such as is used to charge various devices.  You can get them on eBay, or if you're lucky, your local 99 cent store may carry them. Just cut off the USB connector, and solder the power wires to VCC (pin 7) and GND (pin 8) on the ATmega (MAKE SURE TO CHECK THE POLARITY WITH A METER FIRST.  VCC is the positive lead, GND is the negative one). If you solder a USB power supply to your board, make sure to remove the PWR jumper from your USBtinyISP, or unplug your charger from the wall before programming it.