My original concept to create the Sleepduino as an Arduino shield to aid with sleep via white-noise and night-lights – or as a convenient way of getting three RGB LEDs, three buttons and peizoelectric buzzer with adjustable volume into an Arduino – is good, but wouldn’t a stand-alone version be better?
Yes. Yes, it would.
As a result, my order with the fab now includes an original Sleepduino shield along with the new design: the Standalone Sleepduino. Measuring a mere 17.6cm², it’s half the size of the Sleepduino shield. It’s not just a reduced footprint, though: as the name suggests, the Standalone Sleepduino no longer requires an Arduino to operate, shaving about £22 off the cost of the device for those who don’t already have an Arduino or compatible hanging around.
How? By taking the chip at the heart of the Arduino, the ATMega328 microcontroller, and embedding it directly into the middle of the circuit board.
To keep the size down and reduce the number of components required, the design of the Standalone includes a few tweaks over a traditional standalone Arduino creation. First of all, the traditional 16MHz crystal and associated capacitors aren’t there: the Sleepduino doesn’t need an accurate clock to work, so I’m using the 8MHz oscillator built in to the ATMega328 instead. There’s also no sign of a 5V regulator: instead, a USB B socket provides connectivity to a PC USB port or USB-based charger, which already provides a regulated 5V feed.
The Standalone Sleepduino won’t be for everyone: while it’s technically possible to reprogram it in the same way as the newly-renamed Sleepduino Shield, it involves having an existing Arduino or AVR programmer and taking the microcontroller off the board. If you’re looking for something to hack, the Sleepduino Shield will still be the better option; that goes doubly if you’ve already got an Arduino.
For those who just want a combination nightlight – with 334 possible colour combinations and four brightness settings, no less – and white-noise generator, however, the Standalone Sleepduino should prove a winner.
If I get enough interest, I’ll be sending off for a batch of both Standalone Sleepduinos and Sleepduino Shields from a PCB fab in China. I’ll then make them available either as a kit, or pre-assembled if you don’t fancy soldering it up yourself. Once my prototypes arrive, I’ll be doing some demonstration videos too.
Oh, and if you’re wondering how the Standalone Sleepduino looks when it’s not in its lovely compact PCB form, here’s the breadboarded prototype:
Not quite so pretty, huh?
Back-of-the-envelope calculations suggest that it’ll cost me around £13 to produce each Sleepduino Standalone kit, plus a quid or so for a USB A-B cable to go with it.
If you’d like to register interest in snagging yourself a kit or pre-made Sleepduino, drop me a line.