Terminology and functionality

L20G20IS

12/29

DocID029474 Rev 2

3

Terminology and functionality

3.1

Sensitivity

An angular rate gyroscope is a device that produces a positive-going digital output for

counterclockwise rotation around the sensitive axis considered. Sensitivity describes the

gain of the sensor and can be determined by applying a defined angular velocity to it. This

value changes very little over temperature and time.

3.2

Zero-rate level

The zero-rate level describes the actual output signal if there is no angular rate present. The

zero-rate level of highly accurate MEMS sensors is, to some extent, a result of stress to the

sensor and therefore the zero-rate level can slightly change after mounting the sensor on a

printed circuit board or after exposing it to extensive mechanical stress. This value changes

very little over temperature and time.

3.3

Data-ready interrupt and synchronous reading

On the L20G20IS the angular rate data can be retrieved using a synchronous read. To

perform a synchronous read, CTRL4_OIS (0Eh R/W) (DRDY_EN) has to be set to '1' in

order to enable the data-ready interrupt on the DRDY pin (refer to Figure 5). To properly

perform a synchronous read, the angular rate data have to be read every time the DRDY pin

goes high.

The DRDY signal can be latched (default condition) or pulsed if CTRL1_OIS (0Bh

R/W)(DR_DRDY) is set to '1'. When a latched condition is selected, the interrupt goes low

when the high part of one of the output channels is read X-axis angular rate data. The value

is expressed as two’s complement. or DATA_STATUS_OIS (0Ah R) and returns high when

new data is generated. When a pulsed condition is selected, the interrupt behavior is

independent from the read operations and remains high for 75 μsec every time new data is

generated. The DRDY pin is set by default as push-pull output, but it can be configured as

open-drain output by setting CTRL4_OIS (0Eh R/W) (DRDY_OD) to '1'.

3.4

Temperature sensor

The temperature data can be retrieved from the TEMP_OUT_L (01h R), TEMP_OUT_H

(02h R) registers, as two's complement data in 12-bit format left-justified. The output of the

temperature sensor is 0 at 25 °C.