Smartphones, as well as smartwatches, fitness trackers and other wearables are about to get better at guiding users and mapping their sporting achievements even where satellite navigation cannot work, using the latest electronic compass (eCompass) from STMicroelectronics.
Fitness-tracking smartphone apps, smartwatches, and bands need continuous location data for mapping and recording, and accuracy is critical for wearers who like to monitor their progress and share achievements online. A built-in eCompasshelps calculate location when satellite signals are unavailable, such as inside buildings or when running or cycling under tree cover. However, current solutions can give errors of about 10° in latitudes such as Northern Italy or Northern California. This can put the user off course by 150 meters or more in every 1000 meters travelled.
ST’s LSM303AGReCompass cuts the heading error to less than 4°, leveraging the Company’s proprietary technology for manufacturing high-accuracy magnetic sensors. This enhanced accuracy, combined with ultra-low-power operation consuming up to 50% less than competing devices when in low-power mode, is particularly well suited to high-precision Pedestrian Dead Reckoning (PDR) on mobile devices.
The LSM303AGR also enhances dead-reckoning accuracy in applications such as automotive navigation, and maintains accuracy over the full temperature range from -40°C to 85°C, whereas competing devices can vary by as much as 35% or more over small intervals such as between normal room temperature and human-body temperature.
ST’s new LSM303AGR eCompassis available now, packaged as a 2mm x 2mm x 1mm 12-lead LGA, priced from $1.485 for orders of 1000 pieces.
Further Technical Information:
As an all-in-one eCompass IC fabricated on a single die, the LSM303AGR combines a 3-axis MEMS accelerometer leveraging ST’s proven ThELMA technology and a very compact 3-axis Anisotropic Magneto-Resistive (AMR) sensor that delivers higher sensitivity and lower noise than conventional Hall sensors. ST’s own AMR manufacturing process technology gives the LSM303AGR superior temperature stability compared to alternatives made using Giant Magneto-Resistive (GMR) or Tunnel Magneto-Resistive (TMR) technology. ST’s AMR sensor also has high dynamic range, which further contributes to the device’s accuracy by preventing magnetic saturation in areas of high ambient-field strength.
ST has tested the LSM303AGR’s magnetic-sensing accuracy at various latitudes and recorded superior accuracy and temperature stability over current eCompass ICs and pure magnetic sensors from competing manufacturers.