mlx90333 Melexis Company, mlx90333 Datasheet - Page 25

• Manufacturer Part Number: mlx90333
• Description: Triaxis? 3d-joystick Position Sensor
• Manufacturer: Melexis Company

14.6. FILTER
The MLX90333 includes 3 types of filters:
Note: if the parameter FILTERFIRST is set to “1”, the filtering is active on the digital angle. If set to “0”, the
filtering is active on the output transfer function.
14.6.1. Hysteresis Filter
The FHYST parameter is a hysteresis filter. The output value of the IC is not updated when the digital step
is smaller than the programmed FHYST parameter value. The output value is modified when the
increment is bigger than the hysteresis. The hysteresis filter reduces therefore the resolution to a level
compatible with the internal noise of the IC. The hysteresis must be programmed to a value close to the
noise level.
Please note that for the programmable version, the FHYST parameter is set to 4 by default. If you do not
wish this feature, please set it to “0”.
14.6.2. FIR Filters
The MLX90333 features 6 FIR filter modes controlled with Filter = 0…5. The transfer function is described
below:
The characteristics of the filters no 0 to 5 is given in the Table 1.
3901090333
Rev. 001
90% Response Time
99% Response Time
Efficiency RMS (dB)
Coefficients a
Efficiency P2P (dB)
•
•
•
Filter No (j)
Hysteresis Filter: programmable by the FHYST parameter
Low Pass FIR Filters controlled with the Filter parameter
Low Pass IIR Filter controlled with the Filter parameter and the coefficients FILTER A1 and
FILTER A2
Type
Title
0
… a
5
No Filter
Disable
FILTERFIRST
N/A
Parameter
0
1
1
0
0
FILTER
FHYST
Table 1 - FIR Filters Selection Table
110000
y
2.9
2.9
1
2
2
n
=
Extra Light
∑
i
=
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Tria ⊗ is ™ 3D-Joystick Position Sensor
j
0
1
0 … 11 ; step 0.04
a
i
121000
∑
i
=
4.0
3.6
j
0
2
3
3
Value
0… 6
a
i
0
1
Finite Impulse Response
x
n
−
i
133100
4.7
5.0
3
4
4
Unit
deg
MLX90333
111100
Light
5.6
6.1
4
4
4
122210
Data Sheet
6.2
7.0
5
5
5
Jan 08