MPR081Q_技术文档

MPR081

Rev 0, 06/2007

Freescale Semiconductor

Technical Data

Touch Pad Controller

The MPR081 is a user interface controller which manages a 16-position rotary

touch pad. The MPR081 uses an I²C interface to communicate with the host,

which configures the operation, and an interrupt to advise the host of status

changes.

MPR081

Touch Pad Controller

The interrupt output, IRQ, indicates that rotary status has changed since the

MPR081 was last read. The maximum interrupt frequency can be limited to

sacrifice system response time in favor of power consumption for systems that

wake up out of sleep to respond to interrupts.

Bottom View

Features

•

1.8 V to 3.6 V operation

150 µA average supply current (all touch pads being monitored)

1 µA standby current

Supports a 16-position rotary interface

16-LEAD QFN

CASE 1679

Proprietary false touch rejection technology

Ongoing pad analysis and detection not reset by EMI events

Rotary data changes are delivered from a FIFO for shortest access time

IRQ output advises when FIFO has data

System can set interrupt behavior as immediate after event, or program a

minimum time between successive interrupts

Current rotary position is always available on demand for polling-based

systems

•

16-LEAD TSSOP

CASE 948F

•

Sounder drive provides audible feedback to simulate mechanical key clicks

Digital output (I²C with custom addressing)

16-pin QFN and TSSOP packages

Top View

-40°C to +85°C operating temperature range

Implementations

•

Control Panels

Switch Replacements

Rotary and Linear Sliders

Touch Pads

RS

RST

MPR081Q

RSW

RW

IRQ

VDD

Typical Applications

VSS

RNW

•

Appliances

PC Peripherals

Access Controls

MP3 Players

Remote Controls

Mobile Phones

RST

RN

RNE

RE

IRQ

VDD

ORDERING INFORMATION

MPR081EJ

VSS

RSE

RS

Temperature

Range

Case

Number

Rotary

Slider

Device Name

SCL

SDA

RSW

RW

MPR081Q

1679

(16-Lead QFN)

AD0

-40°C to +85°C

16-Positions

SOUNDER

RNW

MPR081EJ

948F

(16-Lead TSSOP)

Figure 1. Pin Connections

Table 1. Absolute Maximum Ratings

Rating

Symbol

Value

Unit

Voltage (with respect to VSS)

—

VDD

All other pins

-0.3 to +3.8

VSS-0.3 to VDD+0.3

V

Operating Temperature Range

Storage Temperature Range

T_A

-40 to +85

°C

T_STG

-55 to +150

Table 2. ESD and Latch-Up Protection Characteristics

Rating

Human Body Model

Symbol

HBM

MM

Value

±2000

±200

±500

±100

Unit

V

Machine Model

V

Charge Device Model

CDM

—

V

Latch-Up Current at T_A= 85°C

mA

Table 3. DC Characteristics

(Typical Operating Circuit, V+ =1.8 V to 3.6 V, T_A= T_MINto T_MAX, unless otherwise noted. Typical values are at V+ = 3.3 V, T_A= +25°C.)

Characteristic

Symbol

Conditions

—

Min

Typ

Max

Units

V

Operating Supply Voltage

V+

I₊

1.8

3.6

Standby Current

SCL and SDA at V+ or GND

TBD

µA

(I²C Interface idle)

Input High Voltage

SDA, SCL

V_IH

V_IL

—

0.7 x VDD

—

V

Input Low Voltage

SDA, SCL

—

0.35 x VDD

Input Leakage Current

SDA, SCL

I_IH, I_IL

—

0.025

—

1

7

µA

pF

V

Input Capacitance

SDA, SCL

—

Output Low Voltage

SDA, IRQ

V_OL

I_OL= 6 mA

—

0.5

Table 4. Interrupt IRQ Timing Characteristics

(Typical Operating Circuit, V+ = 1.8 V to 3.6 V, T_A= T_MINto T_MAX, unless otherwise noted. Typical values are at V+ = 3.3 V, T_A= +25°C.)

Characteristic

Symbol

Conditions

Min

Typ

Max

Units

IRQ Reset delay time from STOP

t_IP

C_L≤ 100 pF

—

TBD

µs

IRQ Reset delay time from acknowledge

t_IR

C_L≤ 100 pF

—

TBD

µs

MPR081

Sensors

2

Freescale Semiconductor

Table 5. I²C AC Characteristics

(Typical Operating Circuit, V+ = 1.8 V to 3.6 V, T_A= T_MINto T_MAX, unless otherwise noted. Typical values are at V+ = 3.3 V, T_A= +25°C.)

Characteristic

Serial Clock Frequency

Symbol

Min

Typ

Max

Units

f_SCL

—

400

kHz

Bus Timeout

F_TIMEOUT

t_BUF

—

31.25

—

ms

µs

Bus Free Time Between a STOP and a START

Condition

1.3

Hold Time, (Repeated) START Condition

Repeated START Condition Setup Time

STOP Condition Setup Time

Data Hold Time

t_{HD, STA}

t_{SU, STA}

t_{SU, STO}

t_{HD, DAT}

t_{SU, DAT}

t_LOW

0.6

—

µs

ns

µs

ns

—

0.9

—

Data Setup Time

100

1.3

0.7

—

SCL Clock Low Period

—

SCL Clock High Period

t_HIGH

—

Rise Time of Both SDA and SCL Signals,

Receiving

t_R

20+0.1C_b

300

Fall Time of Both SDA and SCL Signals,

Receiving

t_F

—

20+0.1C_b

300

ns

Fall Time of SDA Transmitting

Pulse Width of Spike Suppressed

Capacitive Load for Each Bus Line

t_F.TX

t_SP

—

20+0.1C_b

250

—

ns

pF

50

—

C_b

400

MPR081

Sensors

Freescale Semiconductor

3

Table 6. Pin Description

Name

Function

1

RST

Reset Input. Active low clears the 2-wire interface and puts the device in the same

condition as power-up reset.

2

3

4

5

6

7

IRQ

VDD

VSS

SCL

SDA

AD0

Interrupt Output. IRQ is the active-low open-drain interrupt output signalling new events.

Positive Supply Voltage Bypass VDD to VSS with a 0.1µF ceramic capacitor

Ground

I²C-Compatible Serial Clock Input

I²C-Compatible Serial Data I/O

Address input 0. Connect to VSS to select device slave address 0x4C. Connect to VDD

to select device slave address 0x4D.

8

SOUNDER

Sounder driver output. Connect a piezo-ceramic sounder from this output to ground.

Output is push-pull.

9 - 16

PAD

RNW, RW, RSW, RS,

RSE, RE, RNE, RN

Rotary Touch Inputs. Connect the 8 inputs to a 16-position rotary sensor.

Exposed Pad

Exposed Pad on Package Underside (QFN only). Connect to VSS.

1

2

3

4

5

6

7

8

16

15

14

13

12

11

10

9

RST

RN

16 15 14 13

RNE

RE

IRQ

VDD

1

2

3

4

12

RST

IRQ

RS

MPR081EJ

RSE

RS

VSS

MPR081Q

11

10

9

RSW

RW

SCL

VDD

SDA

RSW

RW

VSS

RNW

AD0

5

6

7

8

SOUNDER

RNW

Figure 2. MPR081 Pinout

MPR081

Sensors

Freescale Semiconductor

4

MASKS

INTERRUPT

CONTROLLER

IRQ

SET

RATE

CLEAR

N

NNW

NNE

NE

NEE

NW

NWW

SDA

SCL

2

I C

ROTARY

POSITION

DECODER

ROTARY

E

SERIAL

W

INTERFACE

POSITION

8

SEE

SE

SWW

SW

RST

AD0

SSE

SSW

S

SOUNDER

16 POSITION ROTARY

CONTROLLER

Figure 3. Internal Block Diagram

MPR081

Sensors

Freescale Semiconductor

5

DETAILED DESCRIPTION

key presses. The MPR081 also uses a standardized user

FUNCTIONAL OVERVIEW

register set to configure the part on power up, and to read

pad, slider and key status. The commonality between

products in the MPR08 family of controllers simplifies

migration between parts.

The MPR081user interface controller monitors various

combinations of capacitive touch pads, capacitive sliders,

capacitive rotaries, and mechanical keys. The device

includes a piezo buzzer driver which generates key click

sounds to provide audible feedback of pad touches and/or

Table 7. MPR08 Family Overview

Product

MPR081

Bus

Sounder

Rotary Slider

Touch Pad Array

Main Attribute

Highest resolution rotary

I²C with RST

Yes

16-Positions

—

20 Pads⁽¹⁾

MPR082

Yes

—

Two independent arrays of 10 touch pads

1. The 20 pads are implemented by two independent arrays of 10 touch pads.

A quick word on terminology:

–

A mechanical keyswitch is a switch containing, at its

simplest, two contacts which have either a high (>10 MΩ)

or a low resistance (<10 kΩ) between them depending on

switch position. Momentary push switches normally are

low resistance when pressed. Latching switches (such as

slide switches) provide high resistance in one position,

low resistance in the other.

–

A split pad is a touch pad whose conductive area is

connected to more than one electrode of the touch

controller. For the MPR08 family, a split pad is always

connected to two electrodes and typically looks like a pair

of interlaced fingers.

A pad array is a collection of full and split pads

interconnected to each other and a number of electrode

lines. The number of pads available in a pad array with N

electrode lines using full and two-electrode split pads is

sum(1 to N), made up of N full pads and sum(1 to (N-1))

split pads. The MPR082 uses two sets of 4 electrode lines

and, therefore, each 4-electrode pad array has a

capability of 4 full pads and sum(1 to 3) or 1+2+3 = 6 split

pads, and a total pad count of sum(1 to 4) or 1+2+3+4 =

10 full plus split pads.

–

A capacitive touch pad is a contactless 'key' which

detects the presence or absence of a finger. The raw

detection output is a single bit giving touch condition.

A capacitive rotary is a group of touch pads arranged in

a ring for which not only the presence or absence of a

finger is detected, but also the position of a finger along

the circumference of the rotary.

–

A capacitive slider is an elongated touch pad for which

not only the presence or absence of a finger is detected,

but also the position of a finger along the length of the

slider. The raw detection output is a single bit giving touch

condition, plus a multi-bit word for position. A typical

application is a volume control, where one end of the

slider corresponds to minimum volume and the other end

to maximum.

–

A pad array with n key lockout will only report one touch

at a time. Multiple simultaneous touches are ignored.

A pad array with 2 key rollover ignores further pads after

touching a first pad. If a pad is touched and held, and then

a second pad is touched, the second pad is ignored. If the

first pad is released while the second pad is still touched,

then the second pad will be reported as a new touch.

–

A full pad is a touch pad whose conductive area is

connected to one electrode of the touch controller and

ground.

–

A pad array with n-key rollover allows any number of

pads will be detected as pressed in succession or

simultaneously without requiring any previous pads to be

released first.

MPR081

Sensors

6

Freescale Semiconductor

SERIAL INTERFACE

bi-directional communication between master(s) and

SERIAL-ADDRESSING

slave(s). A master (typically a microcontroller) initiates all

data transfers to and from the MPR081 and generates the

SCL clock that synchronizes the data transfer.

The MPR081 operates as a slave that sends and receives

data through an I²C 2-wire interface. The interface uses a

serial data line (SDA) and a serial clock line (SCL) to achieve

Figure 4. 2-Wire Serial Interface Timing Details

The MPR081 SDA line operates as both an input and an

open-drain output. A pull-up resistor, typically 4.7 kΩ, is

required on SDA. The MPR081 SCL line operates only as an

input. A pull-up resistor, typically 4.7 kΩ, is required on SCL if

there are multiple masters on the 2-wire interface, or if the

master in a single-master system has an open-drain SCL

output.

Each transmission consists of a START condition

(Figure 5) sent by a master, followed by the MPR081's 7-bit

slave address plus R/W bit, a register address byte, one or

more data bytes, and finally a STOP condition.

Figure 5. Start and Stop Conditions

START AND STOP CONDITIONS

by transitioning SDA from low to high while SCL is high. The

bus is then free for another transmission.

Both SCL and SDA remain high when the interface is not

busy. A master signals the beginning of a transmission with a

START (S) condition by transitioning SDA from high to low

while SCL is high. When the master has finished

BIT TRANSFER

One data bit is transferred during each clock pulse

(Figure 6). The data on SDA must remain stable while SCL is

high.

communicating with the slave, it issues a STOP (P) condition

Figure 6. Bit Transfer

MPR081

Sensors

Freescale Semiconductor

7

ACKNOWLEDGE

SDA line is stable low during the high period of the clock

pulse. When the master is transmitting to the MPR081, the

MPR081 generates the acknowledge bit because the

MPR081 is the recipient. When the MPR081 is transmitting to

the master, the master generates the acknowledge bit

because the master is the recipient.

The acknowledge bit is a clocked 9th bit (Figure 7) which

the recipient uses to handshake receipt of each byte of data.

Thus each byte transferred effectively requires 9 bits. The

master generates the 9^thclock pulse, and the recipient pulls

down SDA during the acknowledge clock pulse, such that the

Figure 7. Acknowledge

THE SLAVE ADDRESS

command. The MPR081 has a factory set I²C slave address

which is normally 1001100 (0x4C). Contact the factory to

request a different I²C slave address, which is available in the

range 0001000 to 1110111 (0x08 to 0xEF).

The MPR081 has a 7-bit long slave address (Figure 5).

The bit following the 7-bit slave address (bit eight) is the R/W

bit, which is low for a write command and high for a read

Figure 8. Slave Address

The MPR081 monitors the bus continuously, waiting for a

START condition followed by its slave address. When a

MPR081 recognizes its slave address, it acknowledges and

is then ready for continued communication.

followed by at least one byte of information. The first byte of

information is the command byte. The command byte

determines which register of the MPR081 is to be written by

the next byte, if received. If a STOP condition is detected after

the command byte is received, then the MPR081 takes no

further action (Figure 9) beyond storing the command byte.

Any bytes received after the command byte are data bytes.

MESSAGE FORMAT FOR WRITING THE MPR081

A write to the MPR081 comprises the transmission of the

MPR081's keyscan slave address with the R/W bit set to 0,

Figure 9. Command Byte Received

MPR081

Sensors

8

Freescale Semiconductor

Any bytes received after the command byte are data bytes.

The first data byte goes into the internal register of the

MPR081 selected by the command byte (Figure 10).

Figure 10. Command and Single Data Byte Received

pointer generally auto-increments after each data byte is read

using the same rules as for a write (Table 11). Thus, a read is

initiated by first configuring the MPR081's command byte by

performing a write (Figure 9). The master can now read 'n'

consecutive bytes from the MPR081, with the first data byte

being read from the register addressed by the initialized

command byte. When performing read-after-write

If multiple data bytes are transmitted before a STOP

condition is detected, these bytes are generally stored in

subsequent MPR081 internal registers because the

command byte address generally auto-increments (Table 8).

MESSAGE FORMAT FOR READING THE MPR081

verification, remember to re-set the command byte's address

because the stored command byte address will generally

have been auto-incremented after the write (Table 8).

The MPR081 is read using the MPR081's internally stored

command byte as address pointer, the same way the stored

command byte is used as address pointer for a write. The

Figure 11. ‘n’ Data Bytes Received

OPERATION WITH MULTIPLE MASTERS

MPR08's address pointer, then master #1's read may be from

an unexpected location.

If the MPR081 is operated on a 2-wire interface with

multiple masters, a master reading the MPR081 should use

repeated start(s) between the write(s) which sets the

MPR081's address pointer, and the read(s) that take the data

from the location(s). This is because it is possible for master

#2 to take over the bus after master #1 has set up the

MPR081's address pointer, but before master #1 has read

the data. If master #2 subsequently re-sets the master of the

DEVICE RESET

The reset input RST is an active-low input. When taken

low, RST clears any transaction to or from the MPR081 on

the serial interface and configures the internal registers to the

same state as a power-up reset (Table 9). The MPR081 then

waits for a START condition on the serial interface.

CONTROLLING AND READING THE MPR081

REGISTER ORGANIZATION

used, the operating current rises because the internal timing

oscillator is running and toggling counters.

The MPR081 is a peripheral that is controlled and

monitored though a small array of internal registers which are

accessed through the I²C bus.

INITIAL POWER-UP

On power-up, the interrupt output IRQ is reset, and IRQ

will go high. The registers are reset to the values shown in

Table 9.

Figure 12. Master Tick Counter and

Pad/Key Input Sampling with Autorepeat

STANDBY MODE

When the serial interface is idle, the MPR081

automatically enters standby mode. If any of the features are

MPR081

Sensors

Freescale Semiconductor

9

INTERRUPT CONTROLLER AND IRQ OUTPUT

circuitry reports status as one of five conditions: rotary

untouched, and rotary touched in one of four positions.

Normally, the rotary is only touched in one position, ideally

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:

The IRQ pin is an open-drain, latching interrupt 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 I²C transmission to

the MPR081, the interrupt is not asserted. Instead, it is

asserted after the I²C transmission is terminated (by a STOP

condition or a repeated START condition), but only if the

affected registers were not read during the I²C

1. Two rotary pads touched at the same time

•

If the two touched rotary pads are both full or both

split, the touches are ignored until one is removed

communication. This avoids unnecessary assertion of the

interrupt.

If one touched rotary pad is full and the other touched

rotary pad is split, the full pad position will be reported.

An interrupt can be enabled for:

If the full pad touch is removed first, the split pad

position now will be reported.

•

Initial touch (when rotary condition goes from

untouched to touched)

2. First one rotary pad is touched and held, then a second

rotary pad is touched and held.

Touch release

•

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.

ROTARY TOUCH INTERFACE

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

Table 8. Register Address Map

Register Address

Register

Address

Auto-Increment

Address

Auto-Increment Loop

D15 D14 D13 D12 D11 D10 D9 D8

FIFO

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

0x00

0x01

0x02

0x03

0x04

0x05

0x06

0x07

0x08

0x09

0x00

0x02

0x00

0x04

0x05

0x06

0x07

0x08

0x09

0x00

FIFO

Fault

Rotary Status

Rotary Configuration

Sensitivity

FIFO

Master Tick Counter

Touch Acquisition Sample Rate

Sounder

Sleep Period

Configuration

FIFO

Table 9. Power-Up Register Configurations

Register Data

D7 D6 D5 D4 D3 D2 D1 D0

Register

Address

Register Function

Power-Up Condition

FIFO

Fault

FIFO is empty

0x00

0x01

0x02

0

No faults

Rotary Status

Rotary is untouched

Rotary Configuration

Rotary is enabled, without interrupts, with

sounder enabled

0x03

1

0

1

Sensitivity

Level is very sensitive

0x04

0x05

0

1

0

1

Master Tick Counter

Master tick period is 10 ms

Touch Acquisition Sample Rate Touch acquisition sample rate is 5 master

tick periods

0x06

0

1

0

Sounder

Sounder is globally enabled, 10 ms of 1 kHz

Sleep mode is disabled

0x07

0x08

0x09

0

1

0

Sleep Period

Configuration

Shutdown mode. IRQ is disabled

MPR081

Sensors

Freescale Semiconductor

10

Table 10. FIFO Register Format

Register

Register Data

D4 D3

Register

Address

R/W

1

D7

D6

D5

D2

D1

D0

More

Flag

Empty Overflow

Flag

FIFO Register⁽¹⁾

0x00

Rotary Pad that has been detected as pressed

Flag

FIFO Status

Clear the FIFO.

Subsequent reads without any intervening

addition(s) to the FIFO will return

1'b0100000

0

Clear FIFO (D7 - D0 data is don’t care; it is not stored)

This data is not the last FIFO item.

FIFO has not overflowed.

1

0

1

X

This data is not the last FIFO item.

FIFO did overflow, discarding the most


型号：	MPR081Q
厂家：	Freescale
描述：	Touch Pad Controller 触摸板控制器外围集成电路控制器
文件：	总22页 (文件大小：324K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MPR081Q [FREESCALE]

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