Choices and consequences
While each design feature and component selection choice had its own clear set of issues, benefits and consequences, as described in the context of the wireless interface, some of those consequences reverberated down the line to manufacturing. For example, the MCU came in a microBGA package and it turned out the contract manufacturer FitBit wanted to use couldn’t handle the pitch size.
In addition, the push to minimize weight affected the pc board, which ended up being only 0.5 mm thick. This meant the team had to take extra steps to reinforce the board as its fragility was affecting yield.
These were just some of the issues the team faced in making a workable, production-worthy design. The final product was light and easy to use, but was unfortunately also easy to lose.
After a 3-mile trial run I returned home to find it missing from my waistband. I ran the trail again – faster, as it was getting dark – but to no avail. The FitBit was gone. But I ran 6 miles that day, so I guess it did make me fitter, so I have to say it works!
PS: Park said that they’re aware of the issue and are reworking the clip design.
Fig.3: Future personal fitness monitors may include energy harvesting technology to keep the battery charged.