Table of Contents
Lidar Lite v3 Operation Manual and Technical Specifications������� 1

Lidar Lite v3 Operation Manual
and Technical Specifications
Laser Safety
 WARNING
This device requires no regular maintenance. In the event that the device
becomes damaged or is inoperable, repair or service must be handled byauthorized, factory-trained technicians only. Attempting to repair or service
the unit on your own can result in direct exposure to laser radiation and therisk of permanent eye damage. For repair or service, contact your dealer or
Garmin® for more information. This device should not be modified or operated
without its housing or optics. Operating this device without a housing andoptics, or operating this device with modified housing or optics that expose thelaser source, may result in direct exposure to laser radiation and the risk ofpermanent eye damage. Removal or modification of the diffuser in front of thelaser optic may result in the risk of permanent eye damage.

Use of controls or adjustments or performance of procedures other than thosespecified in this documentation may result in hazardous radiation exposure.
Garmin is not responsible for injuries caused through the improper use oroperation of this product.
 CAUTION
This device emits laser radiation. This Laser Product is designated Class 1during all procedures of operation. This designation means that the laser issafe to look at with the unaided eye, however it is advisable to avoid looking
into the beam when operating the device and to turn off the module when not
in use.

Documentation Revision Information
Rev

Date

0A

09/2016 Initial release

Changes

Laser Safety������������������������������������������������������������������������������������������������������1
Documentation Revision Information�����������������������������������������������������������������1

Specifications������������������������������������������������������������������������������������� 2

Physical�������������������������������������������������������������������������������������������������������������2
Electrical������������������������������������������������������������������������������������������������������������2
Performance������������������������������������������������������������������������������������������������������2
Interface�������������������������������������������������������������������������������������������������������������2
Laser������������������������������������������������������������������������������������������������������������������2

Connections���������������������������������������������������������������������������������������� 2

Wiring Harness��������������������������������������������������������������������������������������������������2
Connector����������������������������������������������������������������������������������������������������������2
Connector Port Identification�����������������������������������������������������������������������2
I2C Connection Diagrams���������������������������������������������������������������������������������3
Standard I2C Wiring������������������������������������������������������������������������������������3
Standard Arduino I2C Wiring�����������������������������������������������������������������������3
PWM Wiring�������������������������������������������������������������������������������������������������3
PWM Arduino Wiring�����������������������������������������������������������������������������������3

Operational Information��������������������������������������������������������������������� 4

Technology��������������������������������������������������������������������������������������������������������4
Theory of Operation�������������������������������������������������������������������������������������������4
Interface�������������������������������������������������������������������������������������������������������������4
Initialization��������������������������������������������������������������������������������������������������4
Power Enable Pin����������������������������������������������������������������������������������������4
I2C Interface������������������������������������������������������������������������������������������������4Mode Control Pin�����������������������������������������������������������������������������������������4
Settings��������������������������������������������������������������������������������������������������������4

I2C Protocol Information�������������������������������������������������������������������� 6

I2C Protocol Operation��������������������������������������������������������������������������������������7
Register Definitions�������������������������������������������������������������������������������������������7
Control Register List������������������������������������������������������������������������������������7
Detailed Control Register Definitions�����������������������������������������������������������8Frequently Asked Questions����������������������������������������������������������� 12

Must the device run on 5 Vdc? Can it run on 3.3 Vdc instead?�����������������������12
What is the spread of the laser beam?������������������������������������������������������������12
How do distance, target size, aspect, and reflectivity effect returned signal
strength?����������������������������������������������������������������������������������������������������������12
How does the device work with reflective surfaces?���������������������������������������12
Diffuse Reflective Surfaces������������������������������������������������������������������������12
Specular Surfaces�������������������������������������������������������������������������������������12
How does liquid affect the signal?�������������������������������������������������������������������13

1

Specifications
PhysicalConnections
Wiring Harness

Specification
Measurement
Size (LxWxH)
20 × 48 × 40 mm (0.8 × 1.9 × 1.6 in.)
Weight22 g (0.78 oz.)
Operating temperature -20 to 60°C (-4 to 140°F)

Electrical
Specification
Power
Current consumption

Measurement
5 Vdc nominal
4.5 Vdc min., 5.5 Vdc max.
105 mA idle
135 mA continuous operation

Performance
Specification
Range (70% reflective
target)Resolution
Accuracy < 5 m
Accuracy ≥ 5 m

Update rate (70%Reflective Target)
Repetition rate

Measurement
40 m (131 ft)+/- 1 cm (0.4 in.)±2.5 cm (1 in.) typical*±10 cm (3.9 in.) typical
Mean ±1% of distance maximum
Ripple ±1% of distance maximum
270 Hz typical650 Hz fast mode**>1000 Hz short range only
~50 Hz default
500 Hz max*Nonlinearity present below 1 m (39.4 in.)**Reduced sensitivity

Interface
Specification
User interface

l2C interface

PWM interface

Measurement
I2C
PWM
External trigger
Fast-mode (400 kbit/s)
Default 7-bit address 0x62
Internal register access & control
External trigger input
PWM output proportional to distance at 10 μs/cm

Wire ColorRed
OrangeYellow
Green
Blue
Black

There are two basic configurations for this device:• I2C (Inter-Integrated Circuit)—a serial computer bus used tocommunicate between this device and a microcontroller, such as an
Arduino board (“I2C Interface”, page 4).
• PWM (Pulse Width Modulation)—a bi-directional signal transfer methodthat triggers acquisitions and returns distance measurements using themode-control pin (“Mode Control Pin”, page 4).

Connector

You can create your own wiring harness if needed for your project orapplication. The needed components are readily available from many
suppliers.
Part
Connector
housing
Connector
terminal
Wire

Description
6-position, rectangular housing,latch-lock connector receptacle witha 1.25 mm (0.049 in.) pitch.
26-30 AWG crimp socket connector
terminal (up to 6)
UL 1061 26 AWG stranded copper

Manufacturer Part Number
JST
GHR-06V-S
JST

SSHL-002T-P0.2

N/A

N/A

Connector Port Identification

Laser
Specification
Wavelength
Total laser power(peak)
Mode of operation
Pulse width
Pulse train repetition
frequency
Energy per pulse
Beam diameter atlaser aperture
Divergence

Function
5 Vdc (+)
Power enable (internal pull-up)
Mode control
I2C SCLI2C SDA
Ground (-)➊
Measurement
905 nm (nominal)
1.3 W
Pulsed (256 pulse max. pulse train)
0.5 μs (50% duty Cycle)
10-20 KHz nominal

➏
Item

➊

<280 nJ
12 × 2 mm (0.47 × 0.08 in.)
8 mRadian➏

Pin Function
1
5 Vdc (+)
2
3
4
5
6

Power enable (internal pull-up)
Mode control
I2C SCLI2C SDA
Ground (-)

2I2C Connection Diagrams

PWM Wiring

Standard I2C Wiring

➊

➊

➋
➌

➋

➌

➍
➍

➎
➏

➎

Item Description
680µF electrolytic capacitor➊➋ Power ground (-) connection➌ I2C SDA connection➍ I2C SCA connection➎ 5 Vdc power (+) connection

Notes
You must observe the correct polarity when
installing the capacitor.
Black wireBlue wire
Green wire
Red wire
The sensor operates at 4.75 through 5.5 Vdc,
with a max. of 6 Vdc.

Standard Arduino I2C Wiring➊➍

Item Description
Trigger pin on microcontroller➊➋ Monitor pin on microcontroller➌ Power ground (-) connection➍ 1kΩ resistor➎ Mode-control connection➏ 5 Vdc power (+) connection

Notes
Connect the other side of the resistor to thetrigger pin on your microcontroller.
Connect one side of the resistor to the modecontrol connection on the device, and to amonitoring pin on your microcontroller.
Black Wire

Yellow wire
Red wire
The sensor operates at 4.75 through 5.5 Vdc,
with a max. of 6 Vdc.

PWM Arduino Wiring

➋
➌

➊
➋
➌

➎
➍
➎

Item Description
680µF electrolytic capacitor➊➋ I2C SCA connection➌ I2C SDA connection➍ Power ground (-) connection➎ 5 Vdc power (+) connection

Notes
You must observe the correct polarity when
installing the capacitor.
Green wireBlue wire
Black wire
Red wire
The sensor operates at 4.75 through 5.5 Vdc,
with a max. of 6 Vdc.

Item Description
5 Vdc power (+) connection➊➋ Power ground (-) connection➌ Mode-control connection➍ Monitor pin on microcontroller➎ Trigger pin on microcontroller

➏

Notes
Red wire
The sensor operates at 4.75 through 5.5 Vdc,
with a max. of 6 Vdc.
Black Wire
Yellow wire
Connect one side of the resistor to the modecontrol connection on the device, and to amonitoring pin on your microcontroller.
Connect the other side of the resistor to thetrigger pin on your microcontroller.

➏ 1kΩ resistor3Operational Information
Technology

This device measures distance by calculating the time delay between thetransmission of a Near-Infrared laser signal and its reception after reflecting
off of a target. This translates into distance using the known speed of light.
Our unique signal processing approach transmits a coded signature and looks
for that signature in the return, which allows for highly effective detection witheye-safe laser power levels. Proprietary signal processing techniques areused to achieve high sensitivity, speed, and accuracy in a small, low-power,
and low-cost system

Theory of Operation

To take a measurement, this device first performs a receiver bias correction
routine, correcting for changing ambient light levels and allowing maximum
sensitivity.
Then the device sends a reference signal directly from the transmitter tothe receiver. It stores the transmit signature, sets the time delay for “zero”
distance, and recalculates this delay periodically after several measurements.
Next, the device initiates a measurement by performing a series ofacquisitions. Each acquisition is a transmission of the main laser signal while
recording the return signal at the receiver. If there is a signal match, the result
is stored in memory as a correlation record. The next acquisition is summed
with the previous result. When an object at a certain distance reflects thelaser signal back to the device, these repeated acquisitions cause a peakto emerge, out of the noise, at the corresponding distance location in thecorrelation record.
The device integrates acquisitions until the signal peak in the correlation
record reaches a maximum value. If the returned signal is not strong enoughfor this to occur, the device stops at a predetermined maximum acquisition
count.
Signal strength is calculated from the magnitude of the signal record peak
and a valid signal threshold is calculated from the noise floor. If the peak is
above this threshold the measurement is considered valid and the device willcalculate the distance, otherwise it will report 1 cm. When beginning the next
measurement, the device clears the signal record and starts the sequenceagain.

Interface
Initialization

On power-up or reset, the device performs a self-test sequence and initializes
all registers with default values. After roughly 22 ms distance measurements
can be taken with the I2C interface or the Mode Control Pin.

Power Enable Pin

The enable pin uses an internal pullup resistor, and can be driven low to shut
off power to the device.

I2C Interface

This device has a 2-wire, I2C-compatible serial interface (refer to I2CBus Specification, Version 2.1, January 2000, available from Philips
Semiconductor). It can be connected to an I2C bus as a slave device, under
the control of an I2C master device. It supports 400 kHz Fast Mode datatransfer.
The I2C bus operates internally at 3.3 Vdc. An internal level shifter allows thebus to run at a maximum of 5 Vdc. Internal 3k ohm pullup resistors ensure thisfunctionality and allow for a simple connection to the I2C host.
The device has a 7-bit slave address with a default value of 0x62. The
effective 8-bit I2C address is 0xC4 write and 0xC5 read. The device will not
respond to a general call. Support is not provided for 10-bit addressing.

Setting the most significant bit of the I2C address byte to one triggers
automatic incrementing of the register address with successive reads or writes
within an I2C block transfer. This is commonly used to read the two bytes of a
16-bit value within one transfer and is used in the following example.
The simplest method of obtaining measurement results from the I2C interface
is as follows:
1 Write 0x04 to register 0x00.
2 Read register 0x01. Repeat until bit 0 (LSB) goes low.
3 Read two bytes from 0x8f (High byte 0x0f then low byte 0x10) to obtain the
16-bit measured distance in centimeters.
A list of all available control resisters is available on page 7.
For more information about the I2C protocol, see I2C Protocol Operation(page 7).

Mode Control Pin

The mode control pin provides a means to trigger acquisitions and return themeasured distance via Pulse Width Modulation (PWM) without having to use
the I2C interface.
The idle state of the mode control pin is high impedance (High-Z). Pullingthe mode control pin low will trigger a single measurement, and the device
will respond by driving the line high with a pulse width proportional to themeasured distance at 10 μs/cm. A 1k ohm termination resistance is required toprevent bus contention.
The device drives the mode control pin high at 3.3 Vdc. Diode isolation allows
the pin to tolerate a maximum of 5 Vdc.
As shown in the diagram PWM Arduino Wiring (page 3), a simple
triggering method uses a 1k ohm resistor in series with a host output pin topull the mode control pin low to initiate a measurement, and a host input pin
connected directly to monitor the low-to-high output pulse width.
If the mode control pin is held low, the acquisition process will repeat
indefinitely, producing a variable frequency output proportional to distance.
The mode control pin behavior can be modified with the ACQ_CONFIG_REG(0x04) I2C register as detailed in 0x04 (page 8).

Settings

The device can be configured with alternate parameters for the distancemeasurement algorithm. This can be used to customize performance byenabling configurations that allow choosing between speed, range andsensitivity. Other useful features are also detailed in this section. See the fullregister map (Control Register List (page 7) for additional settings not
mentioned here.
Receiver Bias Correction
AddressName

Description

Initial Value

0x00

ACQ_COMMAND

Device command--• Write 0x00: Reset device, all registers return to default values• Write 0x03: Take distance measurement without receiver bias correction• Write 0x04: Take distance measurement with receiver bias correction
Faster distance measurements can be performed by omitting the receiverbias correction routine. Measurement accuracy and sensitivity are adversely
affected if conditions change (e.g. target distance, device temperature, andoptical noise). To achieve good performance at high measurement rates
receiver bias correction must be performed periodically. The recommended
method is to do so at the beginning of every 100 sequential measurement
commands.
Maximum Acquisition Count
AddressName

Description

Initial Value

0x02

SIG_COUNT_VAL

Maximum acquisition count

0x80

The maximum acquisition count limits the number of times the device will
integrate acquisitions to find a correlation record peak (from a returned signal),
which occurs at long range or with low target reflectivity. This controls theminimum measurement rate and maximum range. The unit-less relationshipis roughly as follows: rate = 1/n and range = n^(1/4), where n is the number ofacquisitions.
4Configurable I2C Address

Measurement Quick Termination Detection
AddressName

Description

Initial Value

AddressName

Description

Initial Value

0x04

ACQ_CONFIG_REG

Acquisition mode control

0x08

0x16

UNIT_ID_HIGH

Serial number high byte

Unique0x17

UNIT_ID_LOW

Serial number low byte

Unique0x18

I2C_ID_HIGH

Write serial number high byte for
I2C address unlock

--

0x19

I2C_ID_LOW

Write serial number low byte for
I2C address unlock

--

0x1a

I2C_SEC_ADDR

Write new I2C address after
unlock--0x1e

I2C_CONFIG

Default address responsecontrol

0x00

You can enable quick-termination detection by clearing bit 3 in this register.
The device will terminate a distance measurement early if it anticipates thatthe signal peak in the correlation record will reach maximum value. This allows
for faster and slightly less accurate operation at strong signal strengths without
sacrificing long range performance.
Detection Sensitivity
AddressName

Description

Initial Value

0x1c

THRESHOLD_
BYPASS

Peak detection threshold bypass

0x00

The default valid measurement detection algorithm is based on the peakvalue, signal strength, and noise in the correlation record. This can beoverridden to become a simple threshold criterion by setting a non-zero value.
Recommended non-default values are 0x20 for higher sensitivity with more
frequent erroneous measurements, and 0x60 for reduced sensitivity and fewer
erroneous measurements.
Burst Measurements and Free Running Mode
AddressName

Description

Initial Value

0x04

ACQ_CONFIG_REG

Acquisition mode control

0x08

0x11

OUTER_LOOP_
COUNT

Burst measurement count control

0x00

0x45

MEASURE_DELAY

Delay between automatic
measurements

0x14

The device can be configured to take multiple measurements for eachmeasurement command or repeat indefinitely for free running mode.
OUTER_LOOP_COUNT (0x11) controls the number of times the device will
retrigger itself. Values 0x00 or 0x01 result in the default one measurement percommand. Values 0x02 to 0xfe directly set the repetition count. Value 0xff will
enable free running mode after the host device sends an initial measurement
command.
The default delay between automatic measurements corresponds to a 10
Hz repetition rate. Set bit 5 in ACQ_CONFIG_REG (0x04) to use the delay
value in MEASURE_DELAY (0x45) instead. A delay value of 0x14 roughly
corresponds to 100Hz.
The delay is timed from the completion of each measurement. The means thatmeasurement duration, which varies with returned signal strength, will affectthe repetition rate. At low repetition rates (high delay) this effect is small, but
for lower delay values it is recommended to limit the maximum acquisition
count if consistent frequency is desired.

The I2C address can be changed from its default value. Available addresses
are 7-bit values with a ‘0’ in the least significant bit (even hexadecimal
numbers).
To change the I2C address, the unique serial number of the unit must be readthen written back to the device before setting the new address. The process is
as follows:
1 Read the two byte serial number from 0x96 (High byte 0x16 and low byte0x17).
2 Write the serial number high byte to 0x18.
3 Write the serial number low byte to 0x19.
4 Write the desired new I2C address to 0x1a.
5 Write 0x08 to 0x1e to disable the default address.
This can be used to run multiple devices on a single bus, by enabling one,changing its address, then enabling the next device and repeating theprocess.
The I2C address will be restored to default after a power cycle.
Power Control
AddressName

Description

Initial Value

0x65

POWER_CONTROLPower state control

0x80

NOTE: The most effective way to control power usage is to utilize the enable
pin to deactivate the device when not in use.
Another option is to set bit 0 in this register which disables the receiver circuit,saving roughly 40mA. After being re-enabled, the receiver circuit stabilizes by
the time a measurement can be performed. Setting bit 2 puts the device insleep mode until the next I2C transaction, saving 20mA. Since the wake-up
time is only around 2 m/s shorter than the full power-on time, and bothwill reset all registers, it is recommended to use the enable pin instead.

Velocity
AddressName

Description

Initial Value

0x09

VELOCITY

Velocity measurement output--

The velocity measurement is the difference between the current measurement
and the previous one, resulting in a signed (2’s complement) 8-bit number in
cm. Positive velocity is away from the device. This can be combined with freerunning mode for a constant measurement frequency. The default free runningfrequency of 10 Hz therefore results in a velocity measurement in .1 m/s.

5

I2C Protocol Information
This device has a 2-wire, I2C-compatible serial interface (refer to I2C-Bus Specification, Version 2.1, January 2000, available from Philips Semiconductor). It
can be connected to an I2C bus as a slave device, under the control of an I2C master device. It supports standard 400 kHz data transfer mode. Support is notprovided for 10-bit addressing.
The Sensor module has a 7-bit slave address with a default value of 0x62 in hexadecimal notation. The effective 8 bit I2C address is: 0xC4 write, 0xC5 read. The
device will not presently respond to a general call.

Notes:• This device does not work with repeated START conditions. It must first receive a STOP condition before a new START condition.
• The ACK and NACK items are responses from the master device to the slave device.
• The last NACK in the read is technically optional, but the formal I2C protocol states that the master shall not acknowledge the last byte.

6I2C Protocol Operation

The I2C serial bus protocol operates as follows:
1 The master initiates data transfer by establishing a start condition, which is when a high-to-low transition on the SDA line occurs while SCL is high. The
following byte is the address byte, which consists of the 7-bit slave address followed by a read/write bit with a zero state indicating a write request. A write
operation is used as the initial stage of both read and write transfers. If the slave address corresponds to the module’s address the unit responds by pulling
SDA low during the ninth clock pulse (this is termed the acknowledge bit). At this stage, all other devices on the bus remain idle while the selected device
waits for data to be written to or read from its shift register.
2 Data is transmitted over the serial bus in sequences of nine clock pulses (eight data bits followed by an acknowledge bit). The transitions on the SDA line
must occur during the low period of SCL and remain stable during the high period of SCL.
3 An 8 bit data byte following the address loads the I2C control register with the address of the first control register to be read along with flags indicating if auto
increment of the addressed control register is desired with successive reads or writes; and if access to the internal micro or external correlation processor
register space is requested. Bit locations 5:0 contain the control register address while bit 7 enables the automatic incrementing of control register withsuccessive data blocks. Bit position 6 selects correlation memory external to the microcontroller if set. (Presently an advanced feature)
4 If a read operation is requested, a stop bit is issued by the master at the completion of the first data frame followed by the initiation of a new start condition,
slave address with the read bit set (one state). The new address byte is followed by the reading of one or more data bytes succession. After the slave has
acknowledged receipt of a valid address, data read operations proceed by the master releasing the I2C data line SDA with continuing clocking of SCL. At thecompletion of the receipt of a data byte, the master must strobe the acknowledge bit before continuing the read cycle.
5 For a write operation to proceed, Step 3 is followed by one or more 8 bit data blocks with acknowledges provided by the slave at the completion of eachsuccessful transfer. At the completion of the transfer cycle a stop condition is issued by the master terminating operation.

Register Definitions
Control Register List
Address
0x00
0x01
0x02
0x04
0x09
0x0c
0x0d
0x0e
0x0f
0x10
0x11
0x12
0x14
0x15
0x16
0x17
0x18
0x19
0x1a
0x1c
0x1e
0x40
0x45
0x4c
0x52
0x53
0x5d
0x65



R/W
W
R
R/W
R/W
R
R
R
R
R
R
R/W
R/W
R
R
R
R
W
W
R/W
R/W
R/W
R/W
R/W
R
R
R
R/W
R/W

Name
ACQ_COMMANDSTATUS
SIG_COUNT_VAL
ACQ_CONFIG_REG
VELOCITYPEAK_CORR
NOISE_PEAK
SIGNAL_STRENGTHFULL_DELAY_HIGH
FULL_DELAY_LOW
OUTER_LOOP_COUNTREF_COUNT_VAL
LAST_DELAY_HIGH
LAST_DELAY_LOW
UNIT_ID_HIGH
UNIT_ID_LOW
I2C_ID_HIGH
I2C_ID_LOW
I2C_SEC_ADDR
THRESHOLD_BYPASSI2C_CONFIG
COMMAND
MEASURE_DELAY
PEAK_BCKCORR_DATACORR_DATA_SIGN
ACQ_SETTINGS
POWER_CONTROL

Description
Device command
System status
Maximum acquisition count
Acquisition mode control
Velocity measurement output
Peak value in correlation record
Correlation record noise floor
Received signal strength
Distance measurement high byte
Distance measurement low byte
Burst measurement count control
Reference acquisition countPrevious distance measurement high byte
Previous distance measurement low byte
Serial number high byte
Serial number low byte
Write serial number high byte for I2C address unlock
Write serial number low byte for I2C address unlock
Write new I2C address after unlock
Peak detection threshold bypass
Default address response control
State command
Delay between automatic measurements
Second largest peak value in correlation record
Correlation record data low byte
Correlation record data high byte
Correlation record memory bank selectPower state control

Intial Value--0x800x08------0x01
0x05--Unique
Unique---0x00
0x00-0x14----0x80

Details
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Detailed Control Register Definitions

NOTE: Unless otherwise noted, all registers contain one byte and are read
and write.
0x00
R/W

Name

Description

Initial ValueW

ACQ_COMMAND

Device command

--

Bit
7:0

Function
Write 0x00: Reset FPGA, all registers return to default values
Write 0x03: Take distance measurement without receiver bias correction
Write 0x04: Take distance measurement with receiver bias correction

R/W

Name

Description

Initial ValueR

STATUS

System status

--

Bit
6

Function
Process Error Flag
0: No error detected
1: System error detected during measurement
Health Flag
0: Error detected
1: Reference and receiver bias are operational
Secondary Return Flag
0: No secondary return detected
1: Secondary return detected in correlation record
Invalid Signal Flag
0: Peak detected
1: Peak not detected in correlation record, measurement is invalid
Signal Overflow Flag
0: Signal data has not overflowed
1: Signal data in correlation record has reached the maximum value before
overflow. This occurs with a strong received signal strength
Reference Overflow Flag
0: Reference data has not overflowed
1: Reference data in correlation record has reached the maximum value
before overflow. This occurs periodicallyBusy Flag
0: Device is ready for new command
1: Device is busy taking a measurement

4

3

2

1

0

R/W

Name

Description

Initial Value

R/W

ACQ_CONFIG_REG

Acquisition mode control

0x08

Bit
6

Function
0: Enable reference process during measurement
1: Disable reference process during measurement
0: Use default delay for burst and free running mode
1: Use delay from MEASURE_DELAY (0x45) for burst and free running mode
0: Enable reference filter, averages 8 reference measurements for increased
consistency
1: Disable reference filter
0: Enable measurement quick termination. Device will terminate distancemeasurement early if it anticipates that the signal peak in the correlation
record will reach maximum value.
1: Disable measurement quick termination.
0: Use default reference acquisition count of 5.
1: Use reference acquisition count from REF_COUNT_VAL (0x12).
Mode Select Pin Function Control
00: Default PWM mode. Pull pin low to trigger measurement, device will
respond with an active high output with a duration of 10us/cm.
01: Status output mode. Device will drive pin active high while busy. Can beused to interrupt host device.
10: Fixed delay PWM mode. Pulling pin low will not trigger a measurement.
11: Oscillator output mode. Nominal 31.25 kHz output. The accuracy of thesilicon oscillator in the device is generally within 1% of nominal. This affects
distance measurements proportionally and can be measured to apply acompensation factor.

5
4
3

0x01

5

0x04

0x02
R/W

Name

Description

Initial Value

R/W

SIG_COUNT_VAL

Maximum acquisition count

0x80

Bit
7:0

Function
Maximum number of acquisitions during measurement

2
1:0

0x09
R/W

Name

Description

Initial ValueR

VELOCITY

Velocity measurement output

--

Bit
7:0

Function
Velocity measurement output. The difference between the current
measurement and the previous one, signed (2’s complement) value incentimeters.

0x0c
R/W

Name

Description

Initial ValueR

PEAK_CORR

Peak value in correlation record

--

Bit
7:0

Function
The value of the highest peak in the correlation record.

0x0d
R/W

Name

Description

Initial ValueR

NOISE_PEAK

Correlation record noise floor

--

Bit
7:0

Function
A measure of the noise in the correlation record. Will be slightly above thethird highest peak.

8

0x0e

0x16

R/W

Name

R

SIGNAL_STRENGTH Received signal strength

Description

Initial Value

R/W

Name

Description

Initial Value--R

UNIT_ID_HIGH

Serial number high byte

UniqueBit
7:0

Function
Received signal strength calculated from the value of the highest peak in thecorrelation record and how many acquisitions were performed.

Bit
7:0

Function
Unique serial number of device, high byte.

0x0f
R/W

Name

Description

Initial ValueR

FULL_DELAY_HIGHDistance measurement high byte

--

Bit
7:0

Function
Distance measurement result in centimeters, high byte.

0x17
R/W

Name

Description

Initial ValueR

UNIT_ID_LOW

Serial number low byte

UniqueBit
7:0

Function
Unique serial number of device, high byte.

0x18

0x10
R/W

Name

Description

Initial ValueR

FULL_DELAY_LOWDistance measurement low byte

--

Bit
7:0

Function
Distance measurement result in centimeters, low byte.

0x11
R/W

Name

Description

Initial ValueR/W

OUTER_LOOP_COUNT

Burst measurement count control

0x01

Bit
7:0

Function
0x00-0x01: One measurement per distance measurement command.
0x02-0xfe: Repetition count per distance measurement command.
0xff: Indefinite repetitions after initial distance measurement command.
See ACQ_CONFIG_REG (0x04) and MEASURE_DELAY (0x45) for nondefault automatic repetition delays.

0x12
R/W

Name

Description

Initial Value

R/W

REF_COUNT_VAL

Reference acquisition count

0x05

Bit
7:0

Function
Non-default number of reference acquisitions during measurement. ACQ_CONFIG_REG (0x04) bit 2 must be set.

R/W

Name

Description

Initial ValueW

I2C_ID_HIGH

Write serial number high byte for I2C
address unlock

--

Bit
7:0

Function
Write the value in UNIT_ID_HIGH (0x16) here as part of enabling a nondefault I2C address. See I2C_ID_LOW (0x19) and I2C_SEC_ADDR (0x1a).

0x19
R/W

Name

Description

Initial ValueW

I2C_ID_LOW

Write serial number low byte for I2C
address unlock

--

Bit
7:0

Function
Write the value in UNIT_ID_LOW (0x17) here as part of enabling a non-default
I2C address. See I2C_ID_HIGH (0x18) and I2C_SEC_ADDR (0x1a).

0x1a
R/W

Name

Description

Initial Value

R/W

I2C_SEC_ADDR

Write new I2C address after unlock

--

Bit
7:0

Function
Non-default I2C address.
Available addresses are 7-bit values with a ‘0’ in the least significant bit (evenhexadecimal numbers).
I2C_ID_HIGH (0x18) and I2C_ID_LOW (0x19) must have the correct value forthe device to respond to the non-default I2C address.

0x14
R/W Name

Description

Initial Value

0x1c

R

Previous distance measurement high
byte

--

R/W

Name

Description

Initial Value

R/W

THRESHOLD_
BYPASS

Peak detection threshold bypass

0x00

Bit
7:0

Function
0x00: Use default valid measurement detection algorithm based on the peakvalue, signal strength, and noise in the correlation record.
0x01-0xff: Set simple threshold for valid measurement detection. Values 0x200x60 generally perform well.

Bit
7:0

LAST_DELAY_HIGH

Function
Previous distance measurement result in centimeters, high byte.

0x15
R/W

Name

Description

Initial ValueR

LAST_DELAY_LOWPrevious distance measurement low
byte

--

Bit
7:0



Function
Previous distance measurement result in centimeters, low byte.

0x1e
R/W

Name

Description

Initial Value

R/W

I2C_CONFIG

Default address response control

0x00

Bit

Function930: Device will respond to I2C address 0x62. Device will also respond to
non-default address if configured successfully. See I2C_ID_HIGH (0x18),
I2C_ID_LOW (0x19), and I2C_SEC_ADDR (0x1a).
1: Device will only respond to non-default I2C address. It is recommended toconfigure the non-default address first, then use the non-default address towrite to this register, ensuring success.

0x40
R/W

Name

Description

Initial Value

R/W

COMMAND

State command

--

Bit
2:0

Function
000: Test mode disable, resume normal operation
111: Test mode enable, allows download of correlation record
Select correlation memory bank in ACQ_SETTINGS (0x5d) prior to enabling
test mode.
Once test mode is enabled, read CORR_DATA (0x52) and CORR_DATA_SIGN (0x53) in one transaction (read from 0xd2). The memory index isincremented automatically and successive reads produce sequential data.

0x45
R/W

Name

Description

Initial ValueR/W

MEASURE_
DELAY

Delay between automatic measurements

0x14

Bit
7:0

Function
Non-default delay after completion of measurement before automatic retrigger,in burst and continuous modes. ACQ_CONFIG_REG (0x04) bit 5 must be set.
Value 0xc8 corresponds to 10 Hz repetition rate and 0x14 to roughly 100 Hz.

0x5d
R/W

Name

Description

Initial Value

R/W

ACQ_SETTINGSCorrelation record memory bank select

--

Bit
7:6

Function
11: Access correlation memory bank. Write prior to test mode enable, see
COMMAND (0x40).

0x65
R/W

Name

Description

Initial Value

R/W

POWER_CONTROLPower state control

0x80

Bit
2

Function
1: Device Sleep, wakes upon I2C transaction. Registers are reinitialized,
wakeup time similar to full reset using enable pin.
0: Device awake
1: Disable receiver circuit
0: Enable receiver circuit. Receiver circuit stabilizes by the time ameasurement can be performed.

0

0x4c
R/W

Name

Description

Initial ValueR

PEAK_BCK

Second largest peak value in correlation
record

--

Bit
7:0

Function
The value of the second highest peak in the correlation record.

0x52
R/W

Name

Description

Initial ValueR

CORR_DATA

Correlation record data low byte

--

Bit
7:0

Function
Correlation record data low byte. See CORR_DATA_SIGN (0x53), ACQ_SETTINGS (0x5d), and COMMAND (0x40).

0x53
R/W

Name

Description

Initial ValueR

CORR_DATA_SIGNCorrelation record data high byte

--

Bit
7:0

Function
Correlation record data high byte. Correlation record data is a 2’s complement
9-bit value, and must be sign extended to be formatted as a 16-bit 2’scomplement value. Thus when repacking the two bytes obtained for the I2C
transaction, set the high byte to 0xff if the LSB of the high byte is one.

10



11

Frequently Asked Questions
Must the device run on 5 Vdc? Can it run on 3.3 Vdc
instead?
The device requires 5 Vdc to run properly, so this specification isrecommended and supported.

What is the spread of the laser beam?

At very close distances (less than 1 m) the beam diameter is about the sizeof the aperture (lens). For distances greater than 1 m, you can estimate thebeam diameter using this equation:
Distance/100 = beam diameter at that distance (in whatever units you
measured the distance).
The actual spread is ~8 milli-radians or ~1/2 degree.

How does the device work with reflective surfaces?
Reflective characteristics of an object’s surface can be divided into three
categories (in the real world, a combination of characteristics is typicallypresent):• Diffuse Reflective• Specular• Retro-reflective

Diffuse Reflective Surfaces

Purely diffuse surfaces are found on materials that have a textured qualitythat causes reflected energy to disperse uniformly. This tendency results in a
relatively predictable percentage of the dispersed laser energy finding its way
back to the device. As a result, these materials tend to read very well.

How do distance, target size, aspect, and reflectivity
effect returned signal strength?

The device transmits a focused infrared beam that reflects off of a target,
and a portion of that reflected signal returns to the receiver. The distance iscalculated by taking the difference between the moment of signal transmission
to the moment of signal reception. Successfully receiving a reflected signal isheavily influenced by several factors. These factors include:• Target Distance
The relationship of distance (D) to returned signal strength is an inverse
square. So, with increase in distance, returned signal strength decreases
by 1/D^2 or the square root of the distance.
• Target Size
The relationship of a target’s Cross Section (C) to returned signal strengthis an inverse power of four. The device transmits a focused near-infraredlaser beam that spreads at a rate of approximately 0.5º as distanceincreases. Up to 1 m it is approximately the size of the lens. Beyond 1 m,
the approximate beam spread in degrees can be estimated by dividing the
distance by 100, or ~8 milliradians. When the beam overfills (is larger than)
the target, the signal returned decreases by 1/C^4 or the fourth root of thetarget’s cross section.
• Aspect
The aspect of the target, or its orientation to the sensor, affects theobservable cross section and, therefore, the amount of returned signal
decreases as the aspect of the target varies from the normal.
• Reflectivity
Reflectivity characteristics of the target’s surface also affect the amountof returned signal. In this case, we concern ourselves with reflectivity ofnear infrared wavelengths (“How does the device work with reflective
surfaces?”, page 12).
In summary, a small target can be very difficult to detect if it is distant, poorly
reflective, and its aspect is away from the normal. In such cases, the returned
signal strength may be improved by attaching infrared reflectors to the target,
increasing the size of the target, modifying its aspect, or reducing distancefrom the sensor.

Materials that fall into this category are paper, matte walls, and granite. It
is important to note that materials that fit into this category due to observedreflection at visible light wavelengths may exhibit unexpected results in otherwavelengths. The near infrared range used by the device may detect themas nearly identical. For example, a black sheet of paper may reflect a nearly
identical percentage of the infrared signal back to the receiver as a white
sheet.

Specular Surfaces

Specular surfaces, are found on materials that have a smooth quality thatreflect energy instead of dispersing it. It is difficult or impossible for thedevice to recognize the distance of many specular surfaces. Reflections
off of specular surfaces tend to reflect with little dispersion which causes
the reflected beam to remain small and, if not reflected directly back to thereceiver, to miss the receiver altogether. The device may fail to detect a
specular object in front of it unless viewed from the normal.

Examples of specular surfaces are mirrors and glass viewed off-axis.

12How does liquid affect the signal?

There are a few considerations to take into account if your application requires
measuring distances to, or within, liquid:• Reflectivity and other characteristics of the liquid itself• Reflectivity characteristics of particles suspended in the liquid• Turbidity• Refractive characteristics of the liquid
Reflectivity of the liquid is important when measuring distance to the surface ofa liquid or if measuring through liquid to the bottom of a container(“How does
the device work with reflective surfaces?”, page 12).
It is important to note that measuring distance with the device depends onreflected energy from the transmitted signal being detected by the receiverin the sensor. For that reason, the surface condition of the liquid may play animportant role in the overall reflectivity and detectability of the liquid. In thecase of a flat, highly reflective liquid surface, the laser’s reflected energy may
not disperse adequately to allow detection unless viewed from the normal. By
contrast, small surface ripples may create enough dispersion of the reflectedenergy to allow detection of the liquid without the need to position the sensor
so that the transmitted beam strikes the liquid’s surface from the normal.
Reflectivity of suspended particles is a characteristic that may help or hinder
depending on the application.
Turbidity, or the clarity of a liquid created by the presence or absence ofsuspended particles, can similarly help or hinder measurement efforts. If
the application requires detecting the surface of the liquid, then suspended
particles may help by reflecting more of the transmitted beam back to thereceiver, increasing detectability and permitting measurements to be taken.
It is important to note that, attempting to measure through suspended particles
in a liquid will only be successful if the transmitted beam is allowed to reflect
off of the desired target without first being absorbed or reflected by thesuspended particles.
When the near infrared energy transmitted by the device transitions from theatmosphere to a liquid, the energy may be bent, or refracted, and absorbed
in addition to being dispersed. The degree to which the transmitted beam isrefracted and absorbed is defined by its refraction index. That being said, themost important criteria impacting successful measurement through a liquid
is the amount of dispersion of the transmitted beam and whether any of thedispersed beam makes its way back to the receiver on the device.
Remember that electromagnetic energy travels slower through a liquid andmay affect accuracy of the final measurement output.

13For the latest free software updates (excluding map data) throughout the life of your Garmin products, visit the Garmin Web site at www.garmin.com.

© 2016 Garmin Ltd. or its subsidiaries
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September 2016

190-02088-00_0A

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