From Tommy Thompson to Ronald McDonald™, everyone seems to be step counting these days. But what separates the tools from the trinkets? Let's look inside popular pedometers and find out.  
The microprocessor, the brain of the pedometer, controls the electrical impulses that count and display your steps.








     
The microprocessor in the pedometer performs many different functions from the calculations like distance and calories burned (as describes in the features section) to running the display or controlling memory functions. Some do a small amount of signal processing to help avoid false positives or vibrations that are not steps. Examples of these algorithms include those that limit the number of steps that the pedometer can register in one second (generally 3 steps) or some that count one step only if it is followed by another step within a certain amount of time. These two work fairly well, keeping bumps in the car from registering steps on your pedometer for example. Some pedometers take the latter algorithm to an extreme and only count if a minimum of 5 steps is detected (this includes the Bodytronics and the Freestyle Pro). This causes the pedometer to lose significant amounts of steps throughout the day.

The effectiveness of the microprocessor in the pedometer, as well as the memory and LCD control circuits, determines the overall battery life of the pedometer. Pedometers generally consume very little static power, which is generally limited to illuminating the display. Quality pedometers will blank the leading zeros digits before the number to conserve power (00001 vs. 1).

Dynamic power is only lost on a pedometer when the circuit is closed during a step. Accelerometers, on the other hand, must constantly sample the value of the internal strain gauge, and therefore lose battery life much more quickly. Most accelerometers use a larger CR2032 battery than the smaller LR44 battery to help extend the battery life.

Pedometer manufacturers have several choices in microchip components. The major differences in chip quality include operating temperature range and humidity range, electrostatic shock absorption, and power consumption. Those living in dry environments have a much greater chance of inadvertently shocking the pedometer, and lower quality chips may be destroyed. Lowest-quality chips are suceptible to even small shocks, for example, the McDonalds® Stepometer™ states in the instructions that "Static electricity may cause the unit to reset."

JSC Engineering LLC is an Electrical Engineering Consultant Group specializing in product design & performance testing.

© 2008 JSC Engineering, LLC. Direct reprint requests to webmaster@pedometers.com.