Digispark, the tiny development board

Back in August 2012, an inventive hobbyist called Erik Kettenburg setup aproject on Kickstarter. He wanted funding of $5000 to do a production run of his board, the Digispark. His product was a tiny Arduino based development board, with a huge range of shields to go with it.

Throughout the month while seeking Kickstarter funding, Erik was busy making even more shields and even found time for an enclosure. It is down to his enthusiasm that in September his Kickstarter project ended with a whopping $323,218 of funding pledged!

We loved this project and got in on the action. Finally the first Digisparks have shipped and we have one to show you.

Based on the Arduino platform, the Digispark is tiny at 17.5mm x 19mm (0.69in x 0.75in), it is the by far the smallest development board I have seen.

At the base it has a discreet USB connector built-in to the PCB. On first use, it’s a little stiff to insert into the USB port, but after a couple of uses, it soon loosens-up.

Along the side it has 3 pins for power and across the bottom has 6 I/O pins. With its on-board voltage regulator it provides 500ma at 5 volts and can handle a source voltage of between 5 and 7.35 volts.

The board comes with a choice of pin headers. The choice is between attaching sockets to the board to mount a shield to the top, or pins so it can be inserted on to a breadboard. Since we have a few Digisparks, we tried both ways. For projects, it is quite nice to be able to connect it directly to the breadboard, although you will need a USB extension lead.

Since you have a choice, you need to solder the headers of choice to the board. Providing you have some basic soldering experience, this isn’t difficult.

To keep the board small and affordable, it does come with compromise. It doesn’t have a dedicated chip for USB functions. Instead this is managed using software to emulate the functions normally done over USB. This makes the flashing process different to a standard Arduino development board.

The Digispark comes with drivers for Linux, OSx and Windows. I have tested this using Windows 8 x64 and found the install process to be very easy. It also requires a pre-compiled version of the Arduino IDE, which is customised ready for the Digispark.

When using the Arduino IDE to flash the Digispark, the board must not be connected until the IDE prompts you to insert it. Once inserted there is a 5 second window that the device is considered as a programmable USB device. Longer than this and the flashing process must be re-started again.

Whilst I call this a compromise, it doesn’t cause too many issues. It is just a small learning curve you must go through at the beginning. If you are doing many flashes however I could imagine this would become tiresome. Personally, I had no issue with this.

During the video I flashed a sketch that should print the word “Digispark!” on a LCD display. At the end I attached one of the LCD shields that Eric had designed and you will have noticed that even with adjustments to the contrast I was not able to see any text. This left me confused for about 30 minutes, until after further reading it turns out, I have an early version of the board.

Erik describes very clearly in his wiki, that with the early board versions a track must be cut to enable the LCD display to work. Of course being a Kickstarter reward, it is to be expected that things may not be finalised. The next version of board doesn’t have this need, so the final production models should be fine. The whole point of Kickstarter is to help projects become mature through crowd-sourced funding, so we didn’t mind.

Now it works!

As you can see using the Arduino IDE is just the same as with a standard Arduino development board. The only difference being attaching the device when prompted.

Since it is powered by the popular Amtel ATtiny85 processor, it is limited in the size of program you want load. Of course with its 6x I/O ports, you won’t be expecting the same standard as what you find on the Arduino Uno. However this doesn’t mean it’s not capable. With the miniature size of it, it has advantages over its bigger rivals.

It has a list of 14 shields already available, which range from motor, RGB, Infra Red, etc. Which such a range it really defines this board as capable of many things and I guess the true limit is down to your imagination.

Priced at only $12 it is something to consider for any electronics hobbyist. It is small, low-cost and very flexible in its uses.
At the moment they are only available to pre-order direct from http://digistump.com

Here is the detailed spec :

• Support for the Arduino IDE 1.0+ (OSX/Win/Linux)
• Power via USB or External Source – 5v or 7-35v (automatic selection)
• On-board 500ma 5V Regulator
• Built-in USB (and serial debugging)
• 6 I/O Pins (2 are used for USB only if your program actively communicates over USB, otherwise you can use all 6 even if you are programming via USB)
• 8k Flash Memory (about 6k after bootloader)
• I2C and SPI (vis USI)
• PWM on 3 pins (more possible with Software PWM)
• ADC on 4 pins
• Power LED and Test/Status LED (on Pin0)