MPR03X

Sensors

Freescale Semiconductor

9

4

Modes of Operation

4.1

Introduction

MPR03X’s operation modes are Stop, Run1, and Run2. Stop mode is the start-up and configuration mode.

4.2

Stop Mode

In Stop mode, the MPR03X does not monitor any of the electrodes. This mode is the lowest power state.

4.2.1

Initial Power Up

On power-up, the device is in Stop mode, registers are reset to the initial values shown in Table 4, and MPR03X starts in Stop

mode drawing minimal supply current. The user configurable pin IRQ/ELE2 defaults to being the interrupt output IRQ function.

IRQ is reset on power-up, and so defaults to logic high. Since the IRQ is an open-drain output, IRQ will be high impedance.

4.2.2

Stop Mode Usage

In order to set the configuration registers, the device must be in stop mode. This is achieved by setting the EleEn field in the

Electrode Configuration register to zero.

Table 4. Power-Up Register Configurations

Register

Power-Up Condition

Register Address

HEX Value

Touch Status Register

Cleared

0x00

0x00

ELE0 Filtered Data Low Register

Cleared

0x02

0x00

ELE0 Filtered Data High Register

Cleared

0x03

0x00

ELE1 Filtered Data Low Register

Cleared

0x04

0x00

ELE1 Filtered Data High Register

Cleared

0x05

0x00

ELE2 Filtered Data Low Register

Cleared

0x06

0x00

ELE2 Filtered Data High Register

Cleared

0x07

0x00

ELE0 Baseline Value Register

Cleared

0x1A

0x00

ELE1 Baseline Value Register

Cleared

0x1B

0x00

ELE2 Baseline Value Register

Cleared

0x1C

0x00

Max Half Delta Register

Max Half Delta set to 1

0x26

0x00

Noise Half Delta Register

Noise Half Delta Amount set to 1

0x27

0x00

Noise Count Limit Register

Noise Count Limit set to 1

0x28

0x00

ELE0 Touch Threshold Register

Threshold set to 1

0x29

0x00

ELE0 Release Threshold Register

Threshold set to 1

0x2A

0x00

ELE1 Touch Threshold Register

Threshold set to 1

0x2B

0x00

ELE1 Release Threshold Register

Threshold set to 1

0x2C

0x00

ELE2 Touch Threshold Register

Threshold set to 1

0x2D

0x00

ELE2 Release Threshold Register

Threshold set to 1

0x2E

0x00

AFE Configuration Register

6 AFE samples, 16µA charge current

0x41

0x08

Filter Configuration Register

6 touch detection samples, 16ms

detection sample interval

0x43

0x04

Electrode Configuration Register

Stop mode. ELE2/IRQ pin is interrupt

function,

0x44

0x00