Garmin LIDAR-LITE V4 LED OPERATION MANUAL

LIDAR-LITE V4 LED

OPERATION MANUAL AND

TECHNICAL SPECIFICATIONS

Specifications

Specification Measurement

Unit dimensions (L × W × H)

NOTE: Measurements do not include an attached connector.

Weight 14.6 g (0.5 oz.)

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

Storage temperature -40 to 85°C (-40 to 185°F)

Power (operating voltage) 4.75 to 5.25 Vdc

Current consumption 2 mA idle

Input voltage (VIN) 3.3 V Max

Range 5 cm (1.97 in.) to 10 m (32.8 ft.)

Resolution 1 cm (0.4 in.)

Beam divergence 4.77 degrees

LED wavelength 940 nm

Optical aperture 14.9 mm

Update rate I2C: Greater than 200 Hz typical

Interface I2C or ANT

Measurement repeatability

NOTE: As measured indoors to a 90% reflective target; 1 cm is equivalent to 1 standard deviation. Measurements were obtained using high accuracy mode.

52.2 x 24 x 21.2 mm (2.1 x 0.9 x

0.8 in.)

85 mA during an acquisition

ANT: Up to 200 Hz to a 90% reflective target indoors at 2 m in normal operating mode

Configurable for SPI with user applications

± 1 cm to 2 m ± 2 cm to 4 m ± 5 cm to 10 m

52.17 mm (2.05 in.)

44.98 mm (1.77 in.)

10.6 mm (0.42 in.)

24.03 mm (0.95 in.)

1 mm (0.04 in.)

18 mm (0.71 in.)

21.35 mm (0.84 in.)

21.2 mm (0.83 in.)

Mounting Options

Cable tie: You can secure the device to your application using a

3.6 mm (0.14 in.) wide cable tie. You should route the cable tie through the channel in the center of the device.

Double-sided tape: You can secure the bottom of the device to

your application using double-sided tape. For best results, you should select a tape that has a high-strength bond.

Labeling Requirements

The LIDAR-Lite v4 LED device is an FCC-certified transmitter. If you are integrating the device with another product, you must ensure the FCC ID is visible from the outside of your product. You are responsible for meeting any other labeling requirements imposed by the FCC rules and any rules related to the compliance of your end product.

Connections

LIDAR-Lite v4 LED Connection Diagram

The through-holes on the LIDAR-Lite v4 LED device are arranged in 2 rows of 5 holes each, with a 2 mm pitch between each connection.

NOTICE

The LIDAR-Lite v4 LED maximum signal level is 3.3 V. A signal greater than 3.3 V will damage the device.

Device Dimensions

Pin Pin Name Function V Max

VIN 5 V Power 5 V

GND Ground --

I2C SDA I2C Data 3.3 V

GUID-48127269-EFD8-41FF-93EC-D21B0A1EFE74 v2September 2020

Pin Pin Name Function V Max

I2C SCL I2C Clock 3.3 V

GPIOA General Purpose I/O 3.3 V

GPIOB General Purpose I/O 3.3 V

VRETURN nRF52840 DBG 3.3 V

nRESET nRF52840 DBG 3.3 V

SWCLK nRF52840 DBG 3.3 V

SWDIO nRF52840 DBG 3.3 V

Operational Information

Technology

This device measures distance by calculating the time delay between the transmission of a near-infrared light and its reception after reflecting off of a target, using the known speed of light.

The LIDAR-Lite v4 LED contains an nRF52840 SoC from Nordic Semiconductor. This SoC pairs an ARM Cortex-M4 processor with 1 MB of flash memory and 256 KB of RAM. The included

2.4GHz multiprotocol radio and S340 SoftDevice support Ultra Low Power (ULP) wireless technologies, including ANT and Bluetooth® 5 LE.

The LIDAR-Lite v4 LED comes preloaded with an application that allows the developer to communicate with the device using several methods. An I2C interface allows the device to be connected to an external micro-controller, or it can be controlled and operated wirelessly using the ANT wireless protocol in accordance with the ANT Ranging Profile.

The LIDAR-Lite v4 LED also comes preloaded with a Bluetooth LE secure DFU bootloader, which enables wireless software updates using a Bluetooth LE capable device.

Theory of Operation

When the device takes a measurement, it first 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 light 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 the light 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 floor. If the peak is above this threshold, the measurement is considered valid and the device will calculate the distance. If the peak is not above the threshold, it will report 1 cm. When beginning the next measurement, the device clears the signal record and starts the sequence again.

Interface

Initialization

When you turn on or reset the device, it performs a self-test sequence and initializes all registers with default values. After roughly 22 ms, you can take distance measurements using the

I2C interface, the mode control pin, or a wireless ANT connection.

I2C Interface

This device has a 2-wire, I2C-compatible serial interface. 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. Internal 13 kiloohm pull-up resistors ensure this 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 does not respond to a general call. Support is not provided for 10-bit addressing. The device auto-increments 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. See Obtaining

Measurements from the I2C Interface, page 2.

For a list of all available control registers, see Control Register

List, page 5.

For more information about the I2C protocol, see I2C Protocol

Information, page 4.

Obtaining Measurements from the I2C Interface

You can obtain measurement results from the I2C interface.

Write 0x04 to register 0x00.

Read register 0x01.

Repeat step 2 until bit 0 (LSB) goes low.

Read two bytes from 0x10 (low byte 0x10 then high byte

0x11) to obtain the 16-bit measured distance in centimeters.

Settings

You can configure the device with alternate parameters for the distance measurement algorithm. You can use this algorithm to customize performance by enabling configurations that allow speed, range, and sensitivity options. See the full control register list (Control Register List, page 5) for additional settings.

Configurable I2C Address

You can change the I2C address from its default to any 7-bit value. Before you can configure the secondary I2C address, you must first enable flash storage (0xEA). After you configure the secondary I2C address, the address persists if you turn off the device. You can use this process to run multiple devices on a single bus by enabling a device, changing its address, and then enabling the next device. Before you can change the I2C address, the I2C communications bus must read the UNIT_ID and write it back to the device in a single five-data-byte transaction with the new I2C address as the fifth byte. Software template functions for configuring the I2C address are available at https://github.com/garmin/.

Mode Control Pins

The mode control pins can be used to trigger distance measurements and check the status of the LIDAR-Lite v4 LED. These connections are not required. These pins can provide a simpler and faster method of controlling the device, and they are intended to be used in conjunction with the I2C interface. For more information, go to https://github.com/garmin/.

Pin Description Functionality Details

GPIO A TRIGGER LIDAR-Lite v4

LED measurement trigger input

GPIO B MONITOR LIDAR-Lite v4

LED BUSY status output

Toggle to start a distance measurement. The LIDARLite v4 LED starts a distance measurement on either the rising or falling edge. If a distance measurement is triggered while the device is busy, the requested measurement is ignored.

Indicates when the LIDARLite v4 LED is busy. If low, the device is idle and is ready to start a distance measurement. If high, the device is busy taking a distance measurement. Wait for the signal to drop before you toggle GPIO A to trigger a distance measurement.

Triggering and Reading Distance Measurements

Toggle the TRIGGER pin.

Wait for the MONITOR pin to go low.

Read two bytes from 0x10 (low byte 0x10, then high byte

0x11) to obtain the 16-bit measured distance in centimeters. NOTE: If you need to take distance measurements as quickly

as possible, you can reverse steps 2 and 3 so the LIDAR-Lite v4 LED device takes a distance measurement while performing the I2C register read. When this occurs, the LIDAR-Lite v4 LED device is in the process of measuring the distance while the registers are read. The distance returned is the previously triggered measurement.

ANT

ANT is a practical wireless network protocol running in the 2.4 GHz ISM band. Designed for ultra-low power, ease of use, efficiency, and scalability, ANT easily handles peer-to-peer, star, tree, and mesh topologies. Other ANT capable devices can connect to the LIDAR-Lite v4 LED to control it, receive data from it, and configure it wirelessly. ANT messages are sent and received from the LIDAR-Lite v4 LED in accordance to the ANT ranging profile.

For more details about the ANT ranging profile and the capabilities and workings of the ANT wireless protocol, see ANT Ranging Profile and ANT Message Protocol and Usage at

https://github.com/garmin/.

Connecting Wirelessly Using ANT

Before you can connect to the LIDAR-Lite v4 LED using ANT, you must complete these tasks.

• Install Windows 7 Service Pack 1 or higher on your PC

• Install .Net Framework 4.5 or higher on your PC

• Install Visual C++ 2008 SP1 Redistributable Package or higher on your PC

• Purchase a Garmin® ANT USB-m stick Connect the USB ANT stick to your computer.

Download and install the Garmin ANT demo PC application

on your computer (https://github.com/garmin/) . Configure and connect the PC application to the LIDAR-Lite

v4 LED device as specified in the readme file that is included with the Garmin ANT demo PC application.

Activating the Bluetooth LE Bootloader

NOTE: If you are installing a custom unsigned application to the LIDAR-Lite v4 LED, you should first test and debug the custom application using a J-Link debugging probe before you perform wireless updates.

The LIDAR-Lite v4 LED device comes preloaded with a Bluetooth LE bootloader that allows you to update the device software wirelessly. You can use the Nordic Secure DFU bootloader to install an official update signed by Garmin, or a developer can use that bootloader to install a custom, unsigned application.

Disconnect power from the LIDAR-Lite v4 LED device.

Ground the boot pin (GPIO B).

Connect power to the LIDAR-Lite v4 LED device.

The Bluetooth LE bootloader starts advertising as "LLV4 DFU Mode."

Updating the Firmware Using the Bluetooth LE Bootloader

You can use the Bluetooth bootloader to update the LIDAR-Lite v4 LED firmware using a smartphone equipped with Bluetooth LE or a PC equipped with an nRF52 DK or nRF52840 dongle. The firmware is contained in a file called DFU.zip.

Copy the DFU.zip file to a smartphone or PC.

NOTE: You can use the DFU.zip file provided by Garmin or a

custom DFU.zip file. Using the nRF Connect or nRF Toolbox app, start the

firmware upgrade using the DFU.zip file you copied. After the DFU process reaches 100%, verify the new

application runs correctly.

For more information about how to update the nRF52840 using the Nordic secure DFU bootloader, go to https://github.com

/garmin/.

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