Garmin V3HP User Manual

Page 1

LIDAR-Lite v3HP Operation Manual

and Technical Specications

Laser Safety

This device requires no regular maintenance. In the event that the device becomes damaged or is inoperable, repair or service must be handled by authorized, factory-trained technicians only. Attempting to repair or service the unit on your own can result in direct exposure to laser radiation and the risk of permanent eye damage. For repair or service, contact your dealer or

Garmin

for more information. This device has a protective housing which, when in place, prevents human access to laser radiation in excess of the accessible emission limit (AEL) for Class 1 laser products. This device should

not be modied or operated without its housing or optics. Operating this device without a housing and optics, or operating this device with a modied housing

or optics that expose the laser source, may result in direct exposure to laser

radiation and the risk of permanent eye damage. Removal or modication of

the diffuser in front of the laser optic may result in the risk of permanent eye damage.

This device emits laser radiation. Use of controls or adjustments or

performance of procedures other than those specied herein may result in

hazardous radiation exposure. This laser product is designated Class 1 during all procedures of operation. When the ranging feature of the device is activated, a laser emitter of a ranging module may emit laser radiation and the device should not be aimed toward anyone. Avoid looking toward the laser emitter or into the laser radiation (beam) when operating the device. It is advisable to turn off the ranging module when it is not in use. This device must be used only according to the directions and procedures described in this documentation. Do not leave this device within the reach of children.

CLASS 1 LASER PRODUCT Classied EN/IEC 60825-1 2014

This product is in conformity with performance standards for laser products

under 21 CFR 1040, except with respect to those characteristics authorized by Variance Number FDA-2016-V-2943 effective September 27, 2016.

 WARNING

 CAUTION

NOTICE

Table of Contents

LIDAR-Lite v3HP Operation Manual and Technical Specications ��1

Laser Safety ......................................................................................................1

Specications �� 2

Physical .............................................................................................................2

Water Resistance ..............................................................................................2

Electrical ............................................................................................................2

Performance ......................................................................................................2

Interface .............................................................................................................2

Laser ..................................................................................................................2

Connections �� 2

Wiring Harness ..................................................................................................2

I2C Connection Diagrams .................................................................................2

Standard I2C Wiring ....................................................................................2

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 ................................................................................................4

Mode Control Pin .........................................................................................4

Settings ........................................................................................................4

I2C Protocol Information �� 6

I2C Protocol Operation ......................................................................................7

Read Operation ...........................................................................................7

Write Operation ............................................................................................7

Control Register List ....................................................................................7

Detailed Control Register Denitions ...........................................................8

Frequently Asked Questions �� 10

How do I use the device for fast-scanning applications? .................................10

Does the device operate only on 5 Vdc? .........................................................10

What is the spread of the laser beam? ............................................................10

How do distance, target size, aspect, and reectivity affect returned signal

strength? ..........................................................................................................10

How does the device work with reective surfaces? ....................................... 11

Diffuse Reective Surfaces ........................................................................ 11

Specular Surfaces .....................................................................................11

How does liquid affect the signal? ................................................................... 11

Page 2

Specications

Connections

Physical

Specication Measurement

Size (LxWxH) 20 × 48 × 40 mm (0.8 × 1.9 × 1.6 in.)

Weight 22 g (0.78 oz.)

Operating temperature -20 to 60°C (-4 to 140°F)

Water Resistance

Body of this device is rated IPX7, and can wthstand incidental exposure to water of up to 1 meter for up to 30 minutes.

IMPORTANT: The bare wire portion of the wiring harness is not water resistant, and can act as a path for water to enter the device. All bare-wire connections must either be made in a water-tight location or properly sealed.

Water may enter under the transmitting lens. This could affect performance,

but will not affect IPX7 water resistance.

Electrical

Specication Measurement

Power 5 Vdc nominal

4.5 Vdc min., 5.5 Vdc max.

Current consumption 65 mA idle

85 mA during an acquisition

Performance

Specication Measurement

Range (70% reective target) 40 m (131 ft)

Resolution +/- 1 cm (0.4 in.)

Accuracy < 2 m ±5 cm (2 in.) typical*

Accuracy ≥ 2 m ±2.5 cm (1 in.) typical

Mean ±1% of distance maximum Ripple ±1% of distance maximum

Update rate (70% Reective Target) Greater than 1 kHz typical

Reduced sensitivity at high update rates

*Nonlinearity present below 1 m (39.4 in.)

Interface

Specication Measurement

User interface I2C

PWM External trigger

I2C interface Fast-mode (400 kbit/s)

Default 7-bit address 0x62

Internal register access & control

PWM interface External trigger input

PWM output proportional to distance at 10 μs/cm

Laser

Specication Measurement

Wavelength 905 nm (nominal)

Total laser power (peak) 1.3 W

Mode of operation Pulsed (256 pulse max. pulse train)

Pulse width 0.5 μs (50% duty cycle)

Pulse train repetition frequency 10-20 kHz nominal

Energy per pulse <280 nJ

Beam diameter at laser aperture 12 × 2 mm (0.47 × 0.08 in.)

Divergence 8 mRad

Wiring Harness

Wire Color Function

Red 5 Vdc (+)

Orange Power enable (internal pull-up)

Yellow Mode control

Green I2C SCL

Blue I2C SDA

Black Ground (-)

There are two basic congurations for this device:

• I2C (Inter-Integrated Circuit)—a serial computer bus used to communicate between this device and a microcontroller, such as an Arduino board (I2C Interface, page 4).

• PWM (Pulse Width Modulation)—a bi-directional signal transfer method that triggers acquisitions and returns distance measurements using the mode-control pin (Mode Control Pin, page 4).

I2C Connection Diagrams

Standard I2C Wiring

➊

➋

➌ ➍

➎

➏ ➐

Item Description Notes

680µF electrolytic capacitor You must observe the correct polarity when

➊

Power ground (-) connection Black wire

➋

I2C SDA connection Blue wire

➌

I2C SCL connection Green wire

➍

4.7kΩ pull-up resistor

➎

(not required in all applications)

5 Vdc power (+) connection Red wire

➏

Logic rail connection The pull-up resistors connected to both I2C

➐

installing the capacitor.

In installations with long cable extensions

or with multiple devices on the I2C bus, you must install a 1kΩ to 10kΩ pull-up resistor on each I2C wire to account for cable

capacitance.

It is recommended to start with 4.7kΩ

resistors and adjust if necessary.

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

wires must connect to the logic rail on your microcontroller board.

Page 3

Standard Arduino I2C Wiring

➊

➋

➌

➍

PWM Arduino Wiring

➊

➋

➎

➐

➏

Item Description Notes

680µF electrolytic capacitor You must observe the correct polarity when

➊

Pull-up resistor connection

➋

(not required in all applications)

4.7kΩ pull-up resistor

➌

(not required in all applications)

I2C SDA connection Blue wire

➍

I2C SCL connection Green wire

➎

5 Vdc power (+) connection Red wire

➏

Power ground (-) connection Black wire

➐

installing the capacitor.

In installations with long cable extensions

or with multiple devices on the I2C bus, you

must connect the pull-up resistors on the SDA and SCL wires to the logic rail on your microcontroller board.

On an Arduino board, this is the 5v pin.

In installations with long cable extensions

or with multiple devices on the I2C bus, you must install a 1kΩ to 10kΩ pull-up resistor on each I2C wire to account for cable

capacitance.

It is recommended to start with 4.7kΩ

resistors and adjust if necessary.

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

➌

➍ ➎

Item Description Notes

5 Vdc power (+) connection Red wire

➊

Power ground (-) connection Black Wire

➋

Mode-control connection Yellow wire

➌

Monitor pin on microcontroller Connect one side of the resistor to the mode-

➍

Trigger pin on microcontroller Connect the other side of the resistor to the

➎

1kΩ resistor

➏

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

control connection on the device, and to a monitoring pin on your microcontroller board.

trigger pin on your microcontroller board.

➏

PWM Wiring

➊

➋

➌

➍

➎ ➏

Item Description Notes

Trigger pin on microcontroller Connect the other side of the resistor to the

➊

Monitor pin on microcontroller Connect one side of the resistor to the mode-

➋

Power ground (-) connection Black Wire

➌

1kΩ resistor

➍

Mode-control connection Yellow wire

➎

5 Vdc power (+) connection Red wire

➏

trigger pin on your microcontroller.

control connection on the device, and to a monitoring pin on your microcontroller.

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

Page 4

Operational Information

Technology

This device measures distance by calculating the time delay between the

transmission of a Near-Infrared laser signal and its reception after reecting off

of a target. This translates into distance using the known speed of light.

Theory of Operation

To take a measurement, this device rst performs a receiver adjustment

routine, correcting for changing ambient light levels and allowing maximum sensitivity.

The device sends a reference signal directly from the transmitter to the 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 of

acquisitions. 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 reects the

laser signal back to the device, these repeated acquisitions cause a peak to emerge, out of the noise, at the corresponding distance location in the correlation record.

The device integrates acquisitions until the signal peak in the correlation record reaches a maximum value. If the returned signal is not strong enough for 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 oor. If the peak is

above this threshold, the measurement is considered valid and the device will

calculate the distance. Otherwise, it will report 1 cm. When beginning the next

measurement, the device clears the signal record and starts the sequence again.

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 Specication, 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 data

transfer.

The I2C bus operates internally at 3.3 Vdc. An internal level shifter allows the bus to run at a maximum of 5 Vdc. Internal 3k functionality 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.

The most signicant bit of the register is the byte that follows the I2C address in a normal transaction. Setting this most signicant 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:

Write 0x04 to register 0x00.

Read register 0x01. Repeat until bit 0 (LSB) goes low.

Ω pullup resistors ensure this

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 the measured 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). Pulling the 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 the

measured distance at 10 μs/cm. A 1k

prevent 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 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

indenitely, producing a variable frequency output proportional to distance. The mode control pin behavior can be modied with the ACQ_CONFIG_REG

(0x04) I2C register as detailed in 0x04 (page 8).

Ω termination resistance is required to

Ω resistor in series with a host output pin to pull

Settings

The device can be congured with alternate parameters for the distance

measurement algorithm. This can be used to customize performance by

enabling congurations that allow choosing between speed, range, and sensitivity. Other useful features are also detailed in this section. See the full

Control Register List (page 7) for additional settings.

Acquisition Command

Address Name Description Initial Value

0x00 ACQ_COMMAND Device command --

• Writing any non-zero value initiates an acquisition.

Maximum Acquisition Count

Address Name Description Initial Value

0x02 SIG_COUNT_VAL Maximum acquisition count 0xFF

The maximum acquisition count limits the number of times the device will

integrate acquisitions to nd a correlation record peak (from a returned signal), which occurs at long range or with low target reectivity. This controls the

minimum measurement rate and maximum range. The unit-less relationship

is roughly as follows: rate = 1/n and range = n^(1/4), where n is the number of

acquisitions.

Measurement Quick Termination Detection

Address Name Description Initial Value

0x04 ACQ_CONFIG_REG Acquisition mode control 0x08

You can enable quick-termination detection by clearing bit 3 in this register (starting with the LSB in this register as bit 0). The device will terminate

a distance measurement early if it anticipates that the signal peak in the correlation record will reach maximum value. This allows for faster and slightly

less accurate operation at strong signal strengths without sacricing long

range performance.

Detection Sensitivity

Address Name Description Initial Value

0x1c THRESHOLD_

BYPASS

The default valid measurement detection algorithm is based on the peak value, signal strength, and noise in the correlation record. This can be overridden to become a simple threshold criterion by setting a non-zero value.

Recommended non-default values are 0x20 for higher sensitivity with more

Peak detection threshold bypass 0x00

Page 5

frequent erroneous measurements, and 0x60 for reduced sensitivity and fewer

erroneous measurements.

Congurable I2C Address

Address Name Description Initial Value

0x16 UNIT_ID_HIGH Serial number high byte Unique

0x17 UNIT_ID_LOW Serial number low byte Unique

0x18 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 response

control

0x00

The I2C address can be changed from its default value. Available addresses are 7-bit values with a ‘0’ in the least signicant bit (even hexadecimal

numbers).

To change the I2C address, the unique serial number of the unit must be read

then written back to the device before setting the new address. The process is

as follows:

Read the two byte serial number from 0x96 (high byte 0x16 and low byte

0x17). Write the serial number high byte to 0x18.

Write the serial number low byte to 0x19.

Write the desired new I2C address to 0x1a.

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 the process.

The I2C address will be restored to default after a power cycle.

Power Control

Address Name Description Initial Value

0x65 POWER_CONTROL Power state control 0

Setting bit 1 in this register disables the receiver circuit, saving roughly

40 mA. After being re-enabled, the receiver circuit stabilizes by the time a

measurement can be performed. NOTE: The most effective way to control power usage is to utilize the enable

pin to deactivate the device when not in use.

Page 6

I2C Protocol Information

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 respond to a general call.

Notes:

• The ACK and NACK items are responses from the master device to the slave device.

• The last NACK in the read is optional, but the formal I2C protocol states that the master shall not acknowledge the last byte.

Page 7

I2C Protocol Operation

This protocol description uses the term master to refer to the Arduino

controller, and uses the term LIDAR device to refer to the LIDAR-Lite v3HP device acting as a slave on the I2C bus.

When working with the I2C serial bus protocol, the device operates as follows:

The master initiates data transfer by establishing a start condition, which

consists of a high-to-low transition on the SDA line while SCL is high.

The master sends an address byte, which consists of the 7-bit slave

address.

The master sends 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 LIDAR device address, the LIDAR

device responds by pulling SDA low during the ninth clock pulse. This operation is considered the acknowledge bit. At this stage, all other devices on the bus remain idle while the selected

LIDAR device waits for data to be written to or read from its shift register. Data transmits over the serial bus in sequences of nine clock pulses (eight

data bits followed by an acknowledge bit). These transmissions must occur on the SDA line during the low period of

SCL and remain stable during the high period of SCL.

The master sends an 8-bit data byte following the slave address, which

loads the I2C control register on the LIDAR device with the address of the rst control register to be accessed.

Note: If the high bit (Bit 7) is set, it enables automatic incrementing for successive reads/writes.

The master requests a read operation from the LIDAR device or sends a

write operation to the LIDAR device.

Read Operation

After the master establishes communication with the LIDAR device, obtaining a reading from the LIDAR device operates as follows.

The rst data frame sets the address of the desired read register. The

master sends a stop bit at the completion of the rst data frame.

The master initiates a new start condition, which consists of the slave

address with the read bit set (one state). The master reads one or more data bytes in succession.

The LIDAR device sends an acknowledge bit to the master when it

receives a valid address. The master releases the SDA data line with continued clocking of the

SCL line. The master strobes the acknowledge bit and continues the read cycle.

After the read cycle is done, the master sends a stop condition to complete

the operation.

Write Operation

After the master establishes communication with the LIDAR device, writing to the LIDAR device operates as follows.

The master sends one or more 8-bit data blocks to the LIDAR device.

The LIDAR device sends an acknowledge bit to the master when it

receives and writes a valid data byte. The master releases the SDA data line with continued clocking of the

SCL line. The master strobes the acknowledge bit and continues the write cycle,

if necessary.

After the write cycle is done, the master sends a stop condition to complete

the operation.

Control Register List

Address R/W Name Description Intial Value Details

0x00 W ACQ_COMMAND Device command -- page 8

0x01 R STATUS System status -- page 8

0x02 R/W SIG_COUNT_VAL Maximum acquisition count 0xFF page 8

0x04 R/W ACQ_CONFIG_REG Acquisition mode control 0x08 page 8

0x06 W LEGACY_RESET_EN Enables unit reset -- page 8

0x0e R SIGNAL_STRENGTH Received signal strength -- page 8

0x0f R FULL_DELAY_HIGH Distance measurement high byte -- page 8

0x10 R FULL_DELAY_LOW Distance measurement low byte -- page 8

0x12 R/W REF_COUNT_VAL Reference acquisition count 0x03 page 8

0x16 R UNIT_ID_HIGH Serial number high byte Unique page 8

0x17 R UNIT_ID_LOW Serial number low byte Unique page 9

0x18 W I2C_ID_HIGH Write serial number high byte for I2C address unlock -- page 9

0x19 W I2C_ID_LOW Write serial number low byte for I2C address unlock -- page 9

0x1a R/W I2C_SEC_ADDR Write new I2C address after unlock -- page 9

0x1c R/W THRESHOLD_BYPASS Peak detection threshold bypass 0x00 page 9

0x1e R/W I2C_CONFIG Default address response control 0x00 page 9

0x26 R/W PEAK STACK HIGH BYTE Used for post processing of correlation peak data -- page 9

0x27 R/W PEAK STACK LOW BYTE Used for post processing of correlation peak data -- page 9

0x40 R/W COMMAND State command -- page 9

0x48 R HEALTH STATUS Used to diagnose major hardware issues at initialization -- page 10

0x52 R CORR_DATA Correlation record data low byte -- page 10

0x53 R CORR_DATA_SIGN Correlation record data high byte -- page 10

0x65 R/W POWER_CONTROL Power state control 0 page 10

Page 8

Detailed Control Register Denitions

NOTE: Unless otherwise noted, all registers contain one byte and are read

and write.

0x00

R/W Name Description Initial Value

W ACQ_COMMAND Device command --

Bit Function

7:1 Write any non-zero value to start a measurement

0 Performs a hard reset by reloading the FPGA and returning all registers to

default values

This operation must be enabled by writing 1 to bit 0 on register 0x06. When reset the I2C lines go into a high-z state for up to 10 ms. This has the

potential to cause legacy-microcontroller-interface code to crash.

0x01

R/W Name Description Initial Value

R STATUS System status --

Bit Function

5 Health Flag

0: Error detected 1: Reference and receiver bias are operational

4 Device command regulation ag

0: device is not in DC regulation 1: device is in DC regulation

3 Peak detection ag

0: No signal detected 1: Peak detected

2 Reference Overow Flag

0: Reference data has not overowed 1: Reference data in correlation record has reached the maximum value

before overow (occurs periodically)

1 Signal Overow Flag

0: Signal data has not overowed 1: Signal data in correlation record has reached the maximum value before

overow (occurs with a strong received signal strength)

Additional returns can be evaluated using data downloaded from the peak

stack registers, 0x26 and 0x27 (page 9).

0x02

R/W Name Description Initial Value

R/W SIG_COUNT_VAL Maximum acquisition count 0xFF

Bit Function

7:0 Maximum number of acquisitions during measurement

0x04

R/W Name Description Initial Value

R/W ACQ_CONFIG_REG Acquisition mode control 0x08

Bit Function

7 0: Record download resolution set at 9 bits (legacy)

1: Record download resolution set at 12 bits

6 0: Enable reference process during measurement

1: Disable reference process during measurement

5 0: DC compensation enabled

1: DC compensation disabled

4 0: Enable reference lter, averages multiple reference measurements for

increased consistency

1: Disable reference lter

3 0: Enable measurement quick termination. Device will terminate distance

measurement early if it anticipates that the signal peak in the correlation record will reach maximum value.

1: Disable measurement quick termination.

2 bit unused

1:0 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 be

used 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 the

silicon oscillator in the device is generally within 1% of nominal. This affects

distance measurements proportionally and can be measured to apply a compensation factor.

0x06

R/W Name Description Initial Value

R LEGACY_RESET_EN Enables legacy unit reset --

Bit Function

0 Writing 1 to bit 0 enables the legacy reset operation using the 0x00 register.

0x0e

R/W Name Description Initial Value

R SIGNAL_STRENGTH Received signal strength --

Bit Function

7:0 Received signal strength calculated from the value of the highest peak in the

correlation record and how many acquisitions were performed.

0x0f

R/W Name Description Initial Value

R FULL_DELAY_HIGH Distance measurement high byte --

Bit Function

7:0 Distance measurement result in centimeters, high byte.

0x10

R/W Name Description Initial Value

R FULL_DELAY_LOW Distance measurement low byte --

Bit Function

7:0 Distance measurement result in centimeters, low byte.

0x12

R/W Name Description Initial Value

R/W REF_COUNT_VAL Reference acquisition count 0x03

Bit Function

7:0 Non-default number of reference acquisitions during measurement. ACQ_

CONFIG_REG (0x04) bit 2 must be set.

0x16

R/W Name Description Initial Value

R UNIT_ID_HIGH Serial number high byte Unique

Bit Function

7:0 Unique serial number of device, high byte.

Page 9

0x17

R/W Name Description Initial Value

R UNIT_ID_LOW Serial number low byte Unique

0x1e

R/W Name Description Initial Value

R/W I2C_CONFIG Default address response control 0x00

Bit Function

7:0 Unique serial number of device, high byte.

0x18

R/W Name Description Initial Value

W I2C_ID_HIGH Write serial number high byte for I2C

address unlock

Bit Function

7:0 Write the value in UNIT_ID_HIGH (0x16) here as part of enabling a non-

default I2C address. See I2C_ID_LOW (0x19) and I2C_SEC_ADDR (0x1a).

0x19

R/W Name Description Initial Value

W I2C_ID_LOW Write serial number low byte for I2C

address unlock

Bit Function

7:0 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 Function

7:0 Non-default I2C address.

Available addresses are 7-bit values with a ‘0’ in the least signicant bit (even

hexadecimal numbers).

I2C_ID_HIGH (0x18) and I2C_ID_LOW (0x19) must have the correct value for the device to respond to the non-default I2C address.

0x1c

R/W Name Description Initial Value

R/W THRESHOLD_

BYPASS

Bit Function

7:0 0x00: Use default valid measurement detection algorithm based on the peak

value, signal strength, and noise in the correlation record.

0x01-0xff: Set simple threshold for valid measurement detection. Values 0x200x60 generally perform well.

Peak detection threshold bypass 0x00

Bit Function

5 0: Disables the alternate status mode.

1: Enables an alternate indication status byte at STATUS register 0x01. NOTE: If bit 5 is enabled (1), the status word consists of all ones except for

the bit position selected by bits [2:0] in this I2C CONFIG register (0x1e). This

allows for the reading of the busy status of multiple units sharing the same

active base address 0x62.

4 0: Disables the altrenative I2C address.

1: Enables the alternative I2C address.

3 0: Device will respond to I2C address 0x62. Device will also respond to

non-default address if congured 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 to congure the non-default address rst, then use the non-default address to

write to this register, ensuring success.

2:0 Denes the bit position(s) to remain set as 0 when bit 5 is enabled.

0x26

R/W Name Description Initial Value

R/W PEAK STACK

HIGH BYTE

Bit Function

10:8 For every 11-bit stack value, this resister (0x26) must be read rst. Reading

from this register latches the low order data into 0x27 and increments the

stack pointer.

Writing 0x01 to this register (0x26) resets the stack pointer to the rst element.

Registers read successive values from the peak stack register. Data from the stack register is used for post processing.

0x27

R/W Name Description Initial Value

R/W PEAK STACK

LOW BYTE

Bit Function

7:0 Reading from 0x27 reads the low order data from this register.

Registers read successive values from the peak stack register. Data from the stack register is used for post processing.

0x40

R/W Name Description Initial Value

R/W TEST COMMAND State command --

Bit Function

2:0 000: Test mode disable, resume normal operation

111: Test mode enable, allows download of correlation record Once test mode is enabled, read CORR_DATA (0x52) and CORR_DATA_

SIGN (0x53) in one transaction (read from 0xd2). The memory index is

incremented automatically and successive reads produce sequential data.

Page 10

0x48

R/W Name Description Initial Value

R HEALTH STATUS Used to diagnose major hardware issues

at system initialization.

Bit Function

4:0 Reference value is within normal range.

3 Reference overow occurred during the rst acquisition.

2 An initial acquisition was completed at wake-up to set the initial reference

value.

1 The receiver DC control command is within the normal range.

0 DC regulation was successful during wake-up.

0x52

R/W Name Description Initial Value

R CORR_DATA Correlation record data low byte --

Bit Function

7:0 Correlation record data low byte. See CORR_DATA_SIGN (0x53), ACQ_

SETTINGS (0x5d), and COMMAND (0x40).

0x53

R/W Name Description Initial Value

R CORR_DATA_SIGN Correlation record data high byte --

Bit Function

7:0 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’s complement 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.

0x65

R/W Name Description Initial Value

R/W POWER_CONTROL Power state control 0x80

Bit Function

0 1: Disable receiver circuit

0: Enable receiver circuit. Receiver circuit stabilizes by the time a

measurement can be performed.

Frequently Asked Questions

How do I use the device for fast-scanning applications?

Using the LIDAR-Lite v3HP device for fast-scanning applications may

require you to change the program you used for “continuous” or “burst” mode functions with previous versions of the sensor.

Initiate new measurement command.

Immediately read the distance registers, obtaining the previous

measurement results while the new measurement is occurring. Measurement data stored in the sensor is valid until a new measurement

concludes. Perform other actions while polling the status bit until it indicates an idle

state.

Repeat steps 1 through 3.

NOTES:

• This method uses slightly more I2C overhead, but it allows more efcient polling if you know about your measurement time, which depends on maximum acquisition count settings. You also know exactly when that measurement begins.

• With this approach (and nothing else going on except relentless polling),

the device has been able to reach >1.5 kHz with very small acquisition

count settings.

• You can nd sample Arduinio code for this in the Garmin GitHub

repository at the following location: https://github.com/garmin/LIDARLite_

v3_Arduino_Library/blob/master/examples/ShortRangeHighSpeed/

ShortRangeHighSpeed.ino.

Does the device operate only on 5 Vdc?

The device requires 5 Vdc to function properly.

Connecting the device to a source greater or less than 5 Vdc is not supported,

and may result in poor performance or may damage the device.

What is the spread of the laser beam?

At very close distances (less than 1 m), the beam diameter is about the size of the aperture (lens). For distances greater than 1 m, you can estimate the

beam 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.

NOTICE

How do distance, target size, aspect, and reectivity affect returned signal strength?

The device transmits a focused infrared beam that reects off of a target, and a portion of that reected signal returns to the receiver. The distance is

calculated by taking the difference between the moment of signal transmission

to the moment of signal reception. Successfully receiving a reected signal is heavily inuenced by several factors. These factors include:

• Target Distance The relationship of distance (D) to returned signal strength is an inverse

square. With an increase in distance, the 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 strength

is an inverse power of four. The device transmits a focused near-infrared

laser beam that spreads at a rate of approximately 0.5º as distance

increases. 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 overlls (is larger than) the target, the signal returned decreases by 1/C^4 or the fourth root of the target’s cross section.

Page 11

• Aspect The aspect of the target, or its orientation to the sensor, affects the

observable cross section and, therefore, the amount of returned signal decreases as the aspect of the target varies from the normal.

• Reectivity

Reectivity characteristics of the target’s surface also affect the amount

of returned signal (How does the device work with reective surfaces?,

page 11).

In summary, a small target can be very difcult to detect if it is distant, poorly reective, and its aspect is away from the normal. In such cases, the returned signal strength may be improved by attaching infrared reectors to the target,

increasing the size of the target, modifying its aspect, or reducing distance from the sensor.

How does the device work with reective surfaces?

Reective characteristics of an object’s surface can be divided into three categories:

• Diffuse Reective

• Specular

• Retro-reective

Diffuse Reective Surfaces

Purely diffuse surfaces are found on materials that have a textured quality

that causes reected energy to disperse uniformly. This tendency results in a relatively predictable percentage of the dispersed laser energy nding its way

back to the device. As a result, these materials tend to read very well.

Materials that fall into this category are paper, matte walls, and granite. It

is important to note that materials that t into this category due to observed reection at visible light wavelengths may exhibit unexpected results in other

wavelengths. The near infrared range used by the device may detect them

as nearly identical. For example, a black sheet of paper may reect a nearly

identical percentage of the infrared signal back to the receiver as a white sheet.

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:

• Reectivity and other characteristics of the liquid itself

• Reectivity characteristics of particles suspended in the liquid

• Turbidity

• Refractive characteristics of the liquid

Reectivity of the liquid is important when measuring distance to the surface of

a liquid or if measuring through liquid to the bottom of a container (How does

the device work with reective surfaces?, page 11).

Measuring distance with the device depends on reected energy from the

transmitted signal being detected by the receiver in the sensor. For that reason, the surface condition of the liquid may play an important role in

the overall reectivity and detectability of the liquid. In the case of a at, highly reective liquid surface, the laser’s reected energy may not disperse

adequately to allow detection unless viewed from the normal. By contrast,

small surface ripples may create enough dispersion of the reected energy 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. Reectivity 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 of

suspended particles, can similarly help or hinder measurement efforts. If the application requires detecting the surface of the liquid, then suspended

particles may help by reecting more of the transmitted beam back to the

receiver, increasing detectability and permitting measurements to be taken. Attempting to measure through suspended particles in a liquid will only be

successful if the transmitted beam is allowed to reect off of the desired target without rst being absorbed or reected by the suspended particles.

When the near infrared energy transmitted by the device transitions from the atmosphere to a liquid, the energy may be bent, or refracted, and absorbed in addition to being dispersed. The degree to which the transmitted beam is

refracted and absorbed is dened by its refraction index. That being said, the

most important criteria impacting successful measurement through a liquid is the amount of dispersion of the transmitted beam and whether any of the dispersed beam makes its way back to the receiver on the device.

Electromagnetic energy travels slower through a liquid and may affect

accuracy of the nal measurement output.

Specular Surfaces

Specular surfaces, are found on materials that have a smooth quality that

reect energy instead of dispersing it. It is difcult or impossible for the device to recognize the distance of many specular surfaces. Reections off of specular surfaces tend to reect with little dispersion which causes the reected beam to remain small and, if not reected directly back to the

receiver, 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.

Page 12

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April 2018 190-02088-02_0A

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