SCA61T Series

VTI Technologies Oy

Subject to changes

12/18

www.vti.fi

Doc. nr. 8261900

Rev.A

10

9

8

7

6

5

0

1

4

3

2

CS B

SC K

MIS O

MO S I

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

HIG H IM P E DA N C E

COM M A N D

DAT A OU T

16

17

18

Figure 11.

Command and 11 bit acceleration data transmission over the SPI

2.5

Digital Output to Angle Conversion

The acceleration measurement results in RDAX data register are in 11 bit digital word format. The

data range is from 0 to 2048. The nominal content of RDAX data register in zero angle position is:

Binary: 100 0000 0000

Decimal: 1024

The transfer function from differential digital output to angle can be presented as

[]

[

]

[]

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

=

°

LSB/g

LSB

LSB

arcsin

0

@

Sens

D

D

out

out

α

where;

digital output (RDAX)

digital offset value, nominal value = 1024

α

angle

Sens

sensitivity of the device

As an example following table contains data register values and calculated differential digital

output values with -5, -1 0, 1 and 5 degree tilt angles.

Angle

[°]

Acceleration

[mg]

RDAX (SCA61T-

FAHH1G)

RDAX (SCA61T-

FA1H1G)

-5

-87.16

dec: 881

bin: 011 0111 0001

dec: 953

bin: 011 1011 1001

-1

-17.45

dec: 995

bin: 011 1110 0011

dec: 1010

bin: 011 1111 0010

0

0

dec: 1024

bin: 100 0000 0000

dec: 1024

bin: 100 0000 0000

1

17.45

dec: 1053

bin: 100 0001 1101

dec: 1038

bin: 100 0000 1110

5

87.16

dec: 1167

bin: 100 1000 1111

dec: 1095

bin: 100 0100 0111