Acceleration Sensors Calculate Exact Foot Step Count Without External MCU


Bosch has rolled out new MEMS acceleration sensors specifically designed for motion and fitness tracking in wearables. The BMA456 and BMA423 integrate a step counter for wearables, and therefore eliminate an additional external microcontroller for step counting. This helps reduce system cost and power consumption, and thus speeds up design and time-to-market, according to the firm.

Typical applications for the BMA456 and BMA423 include step counting in wearables such as fitness bands. The sensors can also be used for advanced gesture recognition, such as tilting of the wrist, and can detect activities like running, walking and standing still.

The BMA456 provides 16-bit resolution, noise of only 120 μg/√Hz, and a total offset over its lifetime of only 20 mg. Temperature Coefficient of Offset (TCO) is ±0.3 mg/K, ensuring activity tracking remains accurate under all conditions, Bosch contends.

The sensors come in compact packages measuring 2.0 x 2.0 mm. The BMA456 with a height of only 0.65 mm makes it ideal for space-constrained wearable applications such as fitness trackers, smartwatches, and hearables.


Power consumption of the step counter is low, typically less than 30 μA, which helps maximize battery life in portable devices. The sensors can be used to put wearables into sleep mode even during step-counting, thereby helping to reduce overall power consumption, says the company.

These new sensors provide a complementary alternative to Bosch’s existing sensors for wearables and smartphones. For example, the BMA455 and BMA422 are ultra-small acceleration sensors with integrated Android features designed for low-power smartphone applications.

Bosch is showcasing the new products at the Bosch booth 836 at the Sensors Expo & Conference in San Jose, USA, June 27 – 29, 2017.

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The BMA456 and BMA423 will be available via distributors in August 2017. For further information, view the full Press release.



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