Teardown: Misfit Shine 2 – design win for sub-threshold silicon

January 28, 2016 // By Patric Mannion, EDN
At DesignCon 2016 in Santa Clara, we put the Misfit Shine 2 Fitness + Sleep monitor under the knife, and exposed the latest in low-power technology, processes, and power management techniques.

The Misfit Shine 2 is thinner, stronger, and smarter than, well, the original Shine. As per the maker’s advertisements, it really is beautiful. Clad in T6061 T6 anodized aircraft-grade aluminium with glass-reinforced polycarbonate, the designers wisely opted for a minimalist aesthetic with a capacitive touch user-interface (UI) and visual feedback via 12 LEDs on the face. Tap the face, and the LEDs indicate your daily progress toward goal, followed by the time. You can set which comes first. Photo, above, courtesy of CNET.

The Shine 2 is 8-mm thin, 30.5 mm in diameter, and weighs 8.5 g (with battery installed). It’s water resistant up to 50m and uses a 3-axis accelerometer and magnetometer to sense movement.

A vibration alarm provides status feedback and notifications/alerts, which is useful for phone calls and texts from the paired Apple (iOS 7 or above) or Android (Jelly Bean) phone whenever they’re in a bag or in mute mode. Audio feedback comes from an alarm that’s almost, well, pleasant to hear.

Connectivity to the phone is achieved using a Bluetooth 4.1 radio and motion sensing is accomplished using a three-axis accelerometer and magnetometer working together. Also, by downloading the Misfit Link app you can connect using IFTTT recipes to control your mobile device to play music, take a selfie, or tap the Shine to control one of a plethora of home connect services, called IFTTT “channels,” such as a WeMo switch, Nest thermostat, or even Twitter feeds.

Aside from aesthetics and ease of use, the Shine 2 stands out because the company addressed the common issue of battery life by opting for a coin cell that can last up to six months. This gets around the annoyance of having to recharge all too frequently and hoping it’s done before you leave the house. Having used the first iterations of the Fitbit for a period of time, this was definitely a drawback.

It turns out that its low power consumption was top of the list of reasons that Fossil Group, Inc. gave for buying Misfit when the deal was announced last November. However, sleek design was undermined in the Shine 2 by the poor design of the mechanism for holding the device firmly within the strap. I lost the first one when it got caught on my jacket cuff and went flying into space in a dark theatre. Ironically, the Shine 2 was supposed to have addressed the well-documented “flying Shine” problem using the secure clip (Figure 1). The clip didn’t work, but that’s almost moot now, as Misfit addressed that with the Ray, a completely new design for a fitness monitor that it announced at CES in January 2016, in Las Vegas.

Figure 1 It’s sleek design and ability to go 6 months on a single CR2032 3V coin cell battery made the Misfit Shine 2 an EDN teardown target at DesignCon.

As short as my time was with the Shine 2, I found it to be dead accurate, comfortable to wear, and easy to use, with great software and IFTTT support, and I actually miss the vibrating alerts on my wrist when texts and calls come in.

Anyway, let’s get inside and look at how the sleek design, low power consumption, and high functionality were achieved -- and who won and lost in the move from the original Shine to the Shine 2.[continues]