MPR084EJ Freescale Semiconductor, MPR084EJ Datasheet - Page 20

• Manufacturer Part Number: MPR084EJ
• Description: IC CTLR TOUCH SENSR PROX 16TSSOP
• Manufacturer: Freescale Semiconductor
• Type: Capacitiver

Specifications of MPR084EJ

• Number Of Inputs/keys: 8 Key
• Data Interface: I²C, Serial
• Voltage - Supply: 1.8 V ~ 3.6 V
• Current - Supply: 1.62mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-TSSOP
• Output Type: Voltage
• Interface: I²C
• Input Type: Logic
• Supply Voltage: 3.3 V
• Dimensions: 5 mm L x 4.4 mm W x 1.05 mm H
• For Use With: KITMPR084EVM - KIT EVAL 8-PAD TOUCH MPR084
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

MPR084
20
6.3
The Buffered output is done through a FIFO. The FIFO will buffer every touch that occurs up to 30 values before the buffer
overflows and data is lost. Any time data is read from the FIFO it is pulled from the buffer and the next item becomes available.
The buffer can be cleared (NDF goes high) by either reading the last entry or attempting to write to the register.
The buffer settings are configured in the Touch Pad Configuration Register as described in
6.3.1
The FIFO Register is a read only register for determining the current status of the touch pad. Any time a write is issued to this
register the buffer will be cleared. The I
6.4
The MPR084 can generate a fault under two conditions; an electrode is shorted to VDD, or an electrode is shorted to VSS. Once
a fault is asserted the sensor electrodes will no longer be scanned until the fault is cleared. In the event of multiple faults occurring
at the same time, the sensor controller will report the first fault that is detected during scanning.
short, there is also a fault for when too many keys have been touched. The Max Number of Keys Exceeded status bit is an
instantaneous output that is high when more keys are pressed than allowed by the TPC
Table 14. FIFO Register Field Descriptions
Buffered
FIFO Register
Error
Reset:
Field
MDF
NDF
TRF
OF
3:0
BP
W
7
6
5
4
R
MDF
0
7
= Unimplemented
More Data Flag – The More Data Flag shows whether or not data will remain in the
buffer after the current read.
0 No Data Remaining
1 Data Remaining
No Data Flag – The No Data Flag shows whether or not there is currently data in
the buffer.
0 Buffer currently has data
1 Buffer does not currently have data
Overflow Flag – The Overflow Flag shows whether or not an overflow has occurred.
If this flag is high then the most current data was lost.
0 No Overflow has occurred
1 Overflow has occurred
Touch Release Flag – The Touch Release Flag shows if the current buffer entry is
a touch or release of a pad.
0 Pad is released
1 Pad is touched
Buffered Position – The Buffered Position represents the electrode number that is
currently being displayed by the buffer.
0000 Encoding 0 – Buffered touch of electrode 1
~
0111 Encoding 7 – Buffered touch of electrode 8
NDF
2
C slave address of the FIFO Register is 0x00.
6
1
Figure 23. FIFO Register
OF
5
0
TRF
4
0
Description
3
0
2
0
(Section
Section
BP
I
n addition to the VDD or VSS
3.6).
1
0
3.4.
Freescale Semiconductor
0
0
Sensors