MPR083EJ Freescale, MPR083EJ Datasheet - Page 10

• Manufacturer Part Number: MPR083EJ
• Manufacturer: Freescale

Specifications of MPR083EJ

• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (min): 1.8V
• Operating Supply Voltage (max): 3.6V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Package Type: TSSOP
• Mounting: Surface Mount
• Pin Count: 16
• Lead Free Status / RoHS Status: Compliant

MPR083
10
3
3.1
When using a capacitive touch sensor system the raw data must be filtered and interpreted. This process can be done many
different ways but the method used in the MPR083 is explained in this chapter.
3.2
The rotary interface has to distinguish touch status through varying user conditions (different finger sizes in bare hands or gloves)
and environmental conditions (electrical and RF noise, sensor contamination with dirt or moisture).
The rotary circuitry reports touch status as one of the following two conditions:
The rotary is only touched in one position, ideally near the middle of one of the eight pads. If a touch occurs between pads,
untouched will be reported.
3.3
Since it is unlikely that in a real world case a single independent touch will occur two specific multi-touch response cases are
outlined. Methods for changing the sensitivity of the device will be discussed in another Chapter, but the important part is that the
sensitivity is determined by the strength of an input signal. If more than one input signal is above the selected sensitivity then the
touch sensor controller interprets this in a specific way. This functionality is broken down into two different cases.
3.3.1
Any time two touches are detected at the same time the touch sensor controller recognizes this case and accounts for it. Any
time more than one key is pressed the touches are ignored. Thus the touch sensor controller will show the rotary as untouched.
In most cases one of the two electrodes will receive a stronger signal than the other. If the difference in capacitance is statistically
significant between the pad with the stronger signal will be reported.
This functionality is sometimes called 1-Key Lockout.
3.3.2
Another case is when one rotary pad is touched and held and a second rotary pad is then touched and held. For this situation
the second touch will be ignored and the first touch will continue to be reported.
If the second touch is released before the first touch then the second touch will be completely ignored. But, if the first touch is
released before the second then the system will report that the first key is released and that the second key is now touched. This
functionality is sometimes called 2-Key Rollover.
3.4
The Rotary Configuration Register configures a variety of the MPR083 features. Each of these features is described in following
sections. The I
1.
2.
Touch Detection
Introduction
Understanding the Basics
Rotary untouched
Rotary touched in one of eight positions.
Conditional Output Scenarios
Simultaneous Touches
Sequential Touches
Rotary Configuration Register
2
C slave address of the Rotary Configuration Register is 0x03.
Reset:
W
R
RSE
7
1
= Unimplemented
6
0
0
Figure 14. Rotary Configuration Register
5
0
0
ACE
4
0
RRBE
3
0
RTBE
2
0
1
0
0
Freescale Semiconductor
RE
0
1
Sensors