SCA8X0 datasheet(8/35 Pages) VTI

8 / 35 page

SCA8X0/21X0/3100 Series

VTI Technologies Oy

8/35

www.vti.fi

Doc. Nr. 82 694 00 C

Operation Modes

2.1

Measurement mode

After the startup the acceleration data is immediately available through the SPI registers. There is

no need to initialize the accelerometer before starting to use of it. If the application is requiring

monitoring of the correctness of the operation there are several options available to monitor the

operation status.

2.2

Temperature output

The devices include a temperature measurement function. Temperature data can be read through

the SPI interface. Temperature measurement is not calibrated for absolute accuracy. If absolute

accuracy is needed, it can be achieved through measuring the temperature value in two

temperature points in final application and storing them as a calibration value and calculating the

absolute temperature value by using the two points.

2.3

Self-diagnostic functions

VTI Automotive Digital Accelerometer Platform has a set of built-in self-diagnostic functions to

support the application fail safety. The diagnostic functions cover the accelerometer sensing

element functionality, accelerometer internal operation and signal path functionality

2.3.1

Memory self-diagnostic

Factory calibrated values of the accelerometer are stored in a non-volatile memory. The calibrated

values are read during the device power on into volatile registers that control the operation of the

device. During the startup of the device the calculated sum of non-volatile registers is compared to

the factory calibrated value. The test is done automatically after supplies are set on, after any reset

state of component and after return from power-down mode. Test can also be started by a CTRL-

2.3.2

Signal path self-diagnostic

2.3.2.1

SCA8X0 – single axis accelerometers

Sensor element and signal path is tested by deflecting the proof mass of the sensing element to

both directions over a predefined dynamic range. The test is done automatically during start-up and

it can be repeated by a CTRL-register command. The result of the test is a momentary mass

deflection seen in the output of the device. During the test the accelerometer performs a

comparison of the deflection result to a pre-defined threshold value. When the needed dynamics

have been detected the device will return the result of a passed test in a register. By following the

output of the device on SPI interface it is possible to detect failures through the signal path.

2.3.2.2

SCA21X0 and SCA31X0 – multi axis accelerometers

2.3.2.2.1

Start-up Self Test (STS)

During the application start up or when the accelerometer is affected by the gravity force only it is

possible to detect possible sensing element anomalies by applying a start up self test. The test is

done in a following way: a digitally calculated resultant acceleration of x, y and z-axis is compared

to predefined threshold value. Test is started by CTRL-register command and it is done once when

requested.

2.3.2.2.2

Continuous Self Test (STC)

During device operation the continuous self test is monitoring the sensing element performance.

Digitally calculated self-diagnostic function is compared to predefined threshold value. Test is

started by CTRL-register command and it is calculated continuously on background until disabled.

Possible errors are indicated in an error status register and in SPI frame.

SCA8X0 Folha de dados(PDF) 8 Page - VTI technologies

SCA8X0 Folha de dados(HTML) 8 Page - VTI technologies

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

Folha de dados Download

Ligação URL