19

Shutdown

The sensor can be set in Shutdown mode by writing to

Shutdown register. The SPI port should not be accessed

when Shutdown mode is asserted, except for the power-

up command (writing 0x5a to register 0x3a). (Other ICs on

the same SPI bus can be accessed, as long as the sensor’s

NCS pin is not asserted.)

To deassert Shutdown mode:

1. Drive NCS high, and then low to reset the SPI port.

2. Write 0x5a to Power_Up_Reset register.

3. Wait for at least 50 ms.

4. Read from registers 0x02, 0x03, 0x04, 0x05 and 0x06

(or read these same 5 bytes from burst motion register)

one time regardless of the motion pin state.

5. SROM download.

6. Enable laser by setting Forced_Disable bit (Bit-0) of

LASER_CTRL0 register (address 0x20) to 0.

7. Any non-default register setting must then be reloaded.

NOTES:

1. Manual reset and SROM download are needed after

Frame Capture to restore navigation for motion

reading.

2. There are long wakeup times from Shutdown and

forced Rest. These features should not be used for

power management during normal mouse motion.

The table below shows the state of various pins during

shutdown.

Pin

Status when Shutdown Mode

NCS

High*1

MISO

Hi-Z *2

SCLK

Ignore if NCS = 1 *3

MOSI

Ignore if NCS = 1 *4

MOTION

High

*1 NCS pin must be held to 1 (high) if SPI bus is shared with

other devices. It is recommended to hold to 1 (high)

during Shutdown unless powering up the Sensor. It

must be held to 0 (low) if the sensor is to be re-powered

up from shutdown.

*2 MISO should be either pull up or down during

shutdown in order to meet the low power consumption

specification in the datasheet.

*3 SCLK is ignored if NCS is 1 (high). It is functional if NCS

is 0 (low).

*4 MOSI is ignored if NCS is 1 (high). If NCS is 0 (low), any

commands sent on the MOSI pin will be ignored except

the power-up command).

Power Up

The sensor does not perform an internal power up self-

reset; the Power_Up_Reset register must be written every

time power is applied. The appropriate sequence is as fol-

lows:

1. Apply power to VDD3, VDD1.8 and VDDIO in any order,

with a delay of no more than 100ms in between each

supply. (VDD3 should not be grounded while VDD1.8 is

applied). Ensure all supplies are stable.

2. Drive NCS high, and then low to reset the SPI port.

3. Write 0x5a to Power_Up_Reset register

4. Wait for at least 50 ms.

5. Read from registers 0x02, 0x03, 0x04, 0x05 and 0x06

(or read these same 5 bytes from burst motion register)

one time regardless of the motion pin state

6. SROM download.

7. Enable laser by setting Forced_Disable bit (Bit-0) of

LASER_CTRL0 register to 0.

8. Load configuration for other registers

During power-up there will be a period of time after the

power supply is high but before normal operation. The

table below shows the state of the various pins during

power-up and reset.

State of Signal Pins After VDD is Valid

Pin

On Power-

Up

NCS High

before

Reset

NCS Low

before

Reset

After Reset

NCS

Functional

High

Low

Functional

MISO

Undefined

Hi-Z

Functional

Depends

on NCS

SCLK

Ignored

Ignored

Functional

Depends

on NCS

MOSI

Ignored

Ignored

Functional

Depends

on NCS

MOTION

Undefined

Undefined

Undefined

Functional

LASER_

NEN

Undefined

Undefined

Undefined

Functional

PixArt Imaging Inc.

Track-on-Glass Laser Sensor

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PixArt Imaging Inc.