mpr081 Freescale Semiconductor, Inc, mpr081 Datasheet - Page 10

• Manufacturer Part Number: mpr081
• Description: Touch Pad Controller
• Manufacturer: Freescale Semiconductor, Inc

MPR081
10
INTERRUPT CONTROLLER AND IRQ OUTPUT
which automatically alerts changes to a user-configurable
combination of keyswitches and/or touch pads. IRQ requires
an external pullup resistor, which can be connected to any
voltage up to VDD. When set active low, IRQ is reset high
immediately after the slave address acknowledge of the first
subsequent read or write access to the MPR081. If an
interrupt causing event occurs during an I
the MPR081, the interrupt is not asserted. Instead, it is
asserted after the I
condition or a repeated START condition), but only if the
affected registers were not read during the I
communication. This avoids unnecessary assertion of the
interrupt.
ROTARY TOUCH INTERFACE
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
Table 9. Power-Up Register Configurations
FIFO
Fault
Rotary Status
Rotary Configuration
Sensitivity
Master Tick Counter
Touch Acquisition Sample Rate Touch acquisition sample rate is 5 master
Sounder
Sleep Period
Configuration
Table 8. Register Address Map
FIFO
Fault
Rotary Status
Rotary Configuration
Sensitivity
Master Tick Counter
Touch Acquisition Sample Rate
Sounder
Sleep Period
Configuration
The IRQ pin is an open-drain, latching interrupt output
An interrupt can be enabled for:
The rotary interface has to distinguish touch status through
•
•
Register Function
Initial touch (when rotary condition goes from
untouched to touched)
Touch release
Register
2
C transmission is terminated (by a STOP
FIFO is empty
No faults
Rotary is untouched
Rotary is enabled, without interrupts, with
sounder enabled
Level is very sensitive
Master tick period is 10 ms
tick periods
Sounder is globally enabled, 10 ms of 1 kHz
Sleep mode is disabled
Shutdown mode. IRQ is disabled
D15 D14 D13 D12 D11 D10
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Power-Up Condition
2
C transmission to
0
0
0
0
0
0
0
0
0
0
Register Address
2
C
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
0
0
0
0
1
1
1
0
0
0
D9
0
0
1
1
0
1
1
0
0
1
circuitry reports status as one of five conditions: rotary
untouched, and rotary touched in one of four positions.
near the middle of one of the four pads. If a touch occurs
more or less between pads, either the nearest pad will be
given or the touch will be ignored depending on exact touch
position and finger size. The rotary circuitry interprets multiple
simultaneous rotary touches (more than one rotary pad being
touched at the same time) as best it can. The scenarios are
as follows:
1.
2.
Normally, the rotary is only touched in one position, ideally
D8
0
1
0
1
1
0
1
0
1
0
•
•
•
•
Two rotary pads touched at the same time
First one rotary pad is touched and held, then a second
rotary pad is touched and held.
Register
Address
If the two touched rotary pads are both full or both
split, the touches are ignored until one is removed
If one touched rotary pad is full and the other touched
rotary pad is split, the full pad position will be reported.
position now will be reported.
The second touch will be ignored and the first touch
will continue to be active. If the first touch is removed
while the second pad is still being touched, then the
second pad becomes the only touched pad and so is
reported.
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
If the full pad touch is removed first, the split pad
Register
Address
0x00
0x01
0x02
0x03
0x04
0x05
0x06
0x07
0x08
0x09
D7
0
0
0
1
0
0
0
0
0
0
Auto-Increment
D6
0
0
0
0
0
0
0
0
0
0
Address
0x00
0x02
0x00
0x04
0x05
0x06
0x07
0x08
0x09
0x00
D5
0
0
0
0
0
0
0
0
0
0
Register Data
Freescale Semiconductor
D4
0
0
0
0
0
0
0
0
0
0
FIFO
Auto-Increment Loop
D3
0
0
0
0
0
0
0
0
0
0
D2
0
0
0
0
0
1
1
0
0
0
FIFO
FIFO
D1
Sensors
0
0
0
0
0
0
0
0
0
0
D0
0
0
0
1
0
1
0
1
0
0