DEMOMPR031 Freescale, DEMOMPR031 Datasheet - Page 19

• Manufacturer Part Number: DEMOMPR031
• Manufacturer: Freescale

Specifications of DEMOMPR031

• Lead Free Status / RoHS Status: Compliant

Sensors
Freescale Semiconductor
7.4
From the implementation above, there are two elements that can be configured to yield a wide range of capacitance readings
ranging from 0.455 pF to 2874.39 pF. The two configurable components are the electrode charge current and the electrode
charge time.
The electrode charge current can be configured to equal a range of values between 1 μA and 63 μA. This value is set in the CDC
in the AFE Configuration register
The electrode charge time can be configured to equal a range of values between 500 ns and 32 μS. This value is set in the CDT
in the Filter Configuration Register
7.4.1
The AFE (Analog Front End) Configuration Register is used to set both the Charge/Discharge Current and the number of samples
taken in the lowest level filter. The address of the AFE Configuration Register is 0x41.
Table 12. AFE Configuration Register Field Descriptions
Configuration
AFE Configuration Register
Reset:
Field
CDC
FFI
7:6
5:0
W
R
7
0
(Section
FFI
(Section
= Unimplemented
First Filter Iterations – The first filter iterations field selects the number of samples
taken as input to the first level of filtering.
00 Encoding 0 – Sets samples taken to 6
01 Encoding 1 – Sets samples taken to 10
10 Encoding 2 – Sets samples taken to 18
11 Encoding 3 – Sets samples taken to 34
Charge Discharge Current – The Charge Discharge Current field selects the
supply current to be used when charging and discharging an electrode.
000000 Encoding 0 – Disables Electrode Charging
000001 Encoding 1 – Sets the current to 1uA
~
111111 Encoding 63 – Sets the current to 63uA
6
0
7.4.1).
Figure 25. AFE Configuration Register
8.3.1).
5
0
4
0
Description
3
0
CDC
2
0
1
0
0
0
MPR03X
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