Accurate measurements of angular-motion detection using automotive-qualified gyroscopes will significantly enhance dead-reckoning and/or map-matching capabilities in car navigation and telematics applications. In situations when a GPS signal can’t be seen, such as indoors and in urban canyons between tall buildings, dead-reckoning systems compensate for loss of satellite signal by monitoring motion, distance travelled and altitude. Precise gyroscope readings can also improve map-matching, the process of aligning a sequence of observed user positions with the road network on a digital map, used in a number of applications, including traffic flow analysis and driving directions.
These new dead-reckoning and map-matching capabilities are enabled by ST’s gyroscopes, which employ a single sensing structure for motion measurement along all three orthogonal axes. This eliminates any interference between the axes, significantly increasing measurement precision, coupled with excellent output stability over time and temperature.
The A3G4250D gyroscope measures angular rates up to +/-250dps (degree per second). An on-chip IC interface converts the angular-motion data into a 16-bit digital bit stream that is transmitted with high reliability to a dedicated microcontroller chip through a standard SPI or I2C protocol. The device provides two output lines (interrupt and data ready) and four user-selectable output data rates.
The 3V single-supply sensor integrates power-down and sleep modes and an embedded FIFO (first-in first-out) memory block for smarter power management. The A3G4250D embeds an 8-bit temperature sensor and operates within an extended temperature range from -40 to 85°C. The device is robust to electromagnetic interference and withstands shocks up to 10,000g.
Samples of ST’s A3G4250D are available and volume production will start by Q2 2012.