It seems like it’s a rite of passage for folks to build out their own Arduino compatible boards once reaching a certain level of proficiency. Indeed, for me I wanted to learn the Arduino platform more deeply by building it myself out of component parts. Also I am curious to see how cheaply I can make them.
On the cost front, the total comparable cost of this set of boards is $12.50 each, as compared to $19.95 for an equivalent-functional Arduino Pro from Sparkfun. Not bad! I figure if I did it using the iTeadStudio PCB service, these can be made for $7.80 each in quantity 10.
These are the parts needed to have a fully-functional board, on par with an Arduino Pro from Sparkfun. I separate these out so I can have an apples-to-apples price comparison. Total cost of these parts is $6.61. (All parts listed are from Mouser).
|1||556-ATMEGA328P-PU||Atmel Microcontrollers (MCU) 32KB In-system Flash 20MHz 1.8V-5.5V||$4.28|
|1||571-1-390261-9||IC & Component Sockets 28P ECONOMY TIN SKT||$0.30|
|1||512-LM7805CT||Linear Regulators – Standard 1A Pos Vol Reg||$0.63||Datasheet|
|1||647-USR1C101MDD1TP||Aluminum Electrolytic Capacitors – Leaded 16volt 100uF 20% 85c 6.3X7 2.5LS||$0.23||Datasheet|
|1||647-UVR1E100MDD1TD||Aluminum Electrolytic Capacitors – Leaded 25volts 10uF||$0.03||Datasheet|
|1||815-AWCR-16.00MD||Resonators 16MHz 5V||$0.32||Datasheet|
|1||506-FSM4JSMATR||Pushbutton Switches 6x6x5.0mm 160g 12000||$0.35||Datasheet|
|4||140-50U5-104M-TB-RC||Ceramic Disc Capacitors 50V .1uF Y5U 20% Tol||$0.18|
|1||821-1N4001||Rectifiers Vr/50V Io/1A T/R||$0.16|
|1||604-WP7104HD||Kingbright Standard LED – Through Hole RED DIFFUSED||$0.06|
|1||604-WP7104GD||Kingbright Standard LED – Through Hole GREEN DIFFUSED||$0.07|
These are a few additional parts that are needed to really make the board fully usable. They (or something similar) would be needed also with a Pro.
|1||517-974-01-36||Headers & Wire Housings 36P 1ROW STRT SOCKET||$1.81|
|1||651-1935161||Fixed Terminal Blocks PT 1.5/2-5.0-H||$0.34|
My basic approach was to scrounge the Internet for Arduino clones and pick my favorite ideas from each one, to find a design that I was happy with.
- Arduino Pro Mini from Sparkfun (Schematic)
- Really Bare Bones Board from Modern device (Instructions/Schematic)
- Ardweeny from Makershed (Manual)
- DC Boarduino from Adafruit (Details)
- JeeNode from Jee Labs
- MaxSerial Freeduino
Because I am using plain Atmega328’s from Mouser, I need to get the Arduino bootloader on them. This turns out to be fantastically simple. For one, it’s supported in the IDE, and clearly documented in the Arduino ISP Tutorial. Because I am building a total Arduino clone, all the pieces are in place. The last step is to insert the chip, connect it to another Arduino, and blast that bootloader on there. Simple!
For me, it turned out to be even easier thanks to my Box Header Platform. My connectors break out all the right pins, except the 10->reset connection. So I stacked my box header shield on both units, connected port B, added the 10->reset connection, and it was ready to go.
This is a 1.687 x 2.0996-inch board, which I ordered from pcb.laen.org for $17.70. You get three copies, so that’s $5.90 each.
The biggest thing I learned on this project was to watch out for the height of the components! Not until I went to stack shields on it did I realize that a few parts were just a little too tall for comfort:
- 100uF cap. So I need to find shorter 100uF caps.
- Terminal block. Next time, I’ll push the power terminal block out a little bit so it’s away from the area used by shields.
That’s version one. For version two, I’ll try expanding it further. I have a few ideas:
- Try out the iTeadStudio PCB service at $12 for 10 boards.
- Expand up to the full 50cm x 50cm that the iteadstudio PCB service allows
- Use that extra space to pack on a few components, like…
- 2.4GHz RF radio port (4×2 header)
- Temperature sensor
- Additional 3V regulator, because most interesting peripherals are 3V now
- 5×2 Box Header connectors for peripherals
- Crystal instead of resonator for improved timing
- Additional 2-pin header for power
- …and of course fix the problems noted in ‘Lessons Learned’
After that, version three will be a low-power 3.6V version. The goal for that version will be to run as long as possible on rechargeable AA batteries.