Arduino (Part 1)

If you have been following this blog at all you probably noticed that I have done a fair number of microcontroller projects. In my experience working with the PIC and AVR microcontrollers I ran into a number of issues:

1. The PICBasic programming environment , while easy to learn, only works on Windows
2. The C programming environment for the AVR requires more effort than I wish to put into a casual hobby enterprise and I have been unable to get it working in Linux
   

As I looked for more project ideas I noticed a lot of people using the Arduino development board. The Arduino is an open source hardware and software environment similar in concept to the BASIC Stamp (except it's not expensive). Basically all the Arduino does is provide a standardized microcontroller board using the AVR ATMega168 processor and various power, I/O, and programming connections. They can be purchased as a completed board for around $35 (several versions of unassembled kits are also available). The biggest advantage from my perspective is that the Arduino software is truly cross-platform since it runs in Java and therefore can be used in Windows, Mac OSX and most importantly for me Linux.

One version called the Bare Bones Arduino removes the standard USB-serial adapter from the board itself and instead substitutes a FTDI USB-serial cable to connect the board to your PC. This is done to minimize cost since the adapter cable is a one-time $20 dollar purchase that can be used with an infinite number of compatible boards instead of paying for the adapter chip on the standard Arduino every time you get a new board. Another version of the Arduino called the Boarduino modifies the form factor of the circuit board into one more convenient for use on a solderless breadboard. otherwise it is essentially the same as the Bare Bones Arduino in that it also uses the FTDI adapter cable. Both of these boards are completely interchangeable with the Arduino.

While these are good products, I decided I wanted to build my own version from scratch to better fit my electronics setup. I used the schematic from the Boarduino website to base my design on, but I used the same form factor as the Bare Bones Arduino. Since I use a Graymark 808 Protoboard which has a built in power supplies I removed the power circuitry from my design. In its place I simply put two headers, one for +5V and one for Gnd that connect to the protoboard's power supply (as shown in the pictures above). I also reduced the number of headers (which stab into the solderless breadboard) used to fit the Radio Shack PC board I used for my layout. I retained the power select jumper to choose whether the board is powered by the USB programming cable or the protoboard's power supply. I also left the two indication LEDs, reset button, and the 6 pin ISP and USB programming headers as they are on the Boarduino.

Total cost for my homebrew Arduino was $9 (not including the USB adapter cable).

• FTDI USB to TTL Serial Adapter Cable, 5V version
• Atmel ATMega168 microcontroller
• 16MHz ceramic resonator
• Tactile Pushbutton
• 40 Pin Strip Header
• Strip Header Shunt
• Radio Shack Multi Purpose PC Board, 417 holes