Benewake TF-Luna User manual

TF-Luna Product Manual
TF-Luna LiDAR Module

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page2
Product information
Model: TF-Luna
Full name: TF-Luna LiDAR Module
Manufacturer
Company: Benewake (Beijing) Co. Ltd.
Address: No.28, Xinxi Road, Haidian District, Beijing, PRC
Copyright
This document is protected by copyright. All rights related to it belong to Benewake (Beijing) Co. Ltd.
Reproduction of all or part of this document is permitted only within the scope of copyright law. No
modification, deletion, or translation of this document is permitted without the official written permission
of Benewake (Beijing) Co. Ltd.
All rights reserved © Benewake (Beijing) Co. Ltd.
Certification

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page3
Foreword
Dear users,
Thanks you for choosing Benewake products and it’s our pleasure to help you with any technical
question.
To have a better experience, please read this manual carefully. We try to contain all common problems
and hope you find the deployment and installation easy and fun.
This manual will guide you through the installation and operation process and show you some solution
of common problems. It is still possible that you encounter some difficulties that are not included,
please check our support service ([e-mail]) and don’t hesitate to contact our support
consultants or leave a message on our feedback page of our official website:
http://benewake.com/en/mfeedback.html
We hope you enjoy our product and join our community!
We are Benewake! Our goal is to make the best “Robotic Eyes” in the world!

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page4
Catalog
1Revisions ..................................................................................................................................7
2Cautions....................................................................................................................................7
2.1 About document................................................................................................................7
2.2 About product ...................................................................................................................8
2.3 Common errors and other notes.........................................................................................8
3Principle description and key parameters...................................................................................8
3.1 Ranging Principle..............................................................................................................8
3.2 Basic Characteristic Parameters ........................................................................................9
3.3 Repeatability.....................................................................................................................9
3.4 Ranging Characteristics...................................................................................................10
4Appearance and Structure........................................................................................................11
4.1 Appearance .....................................................................................................................11
5Electrical Characteristics .........................................................................................................11
6Functional Descriptions and Configuration..............................................................................12
6.1 Description about Line Sequence and Connection ...........................................................12
6.2 Serial Port Communication Protocol ...............................................................................12
6.3 I2C Communication........................................................................................................13
6.4 Basic Data Output ...........................................................................................................14
6.5 Continuous Ranging Mode..............................................................................................15
6.6 Trigger Mode ..................................................................................................................15
6.7 On/off Mode ...................................................................................................................15
6.8 Amp Threshold ...............................................................................................................16
6.9 Distance Limit ................................................................................................................16
6.10 Power Saving Mode.....................................................................................................16

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page5
6.11 Ultra-low Power Mode ................................................................................................17
6.11.1 Ultra-low Power Mode with Serial Port Communication .......................................18
6.11.2 Ultra-low Power Mode with I2C communication...................................................19
6.11.3 Caveats..................................................................................................................20
6.12 Single Frequency Mode ...............................................................................................20
6.13 Additional notes ..........................................................................................................20
7Quick Test Guide.....................................................................................................................21
7.1 Required tools for testing ................................................................................................21
7.2 Steps ...............................................................................................................................21
8Firmware upgrade ...................................................................................................................23
Appendix I Serial port output format...............................................................................................24
1. 9-byte/cm (Default).........................................................................................................24
2. PIX .................................................................................................................................24
3. 9-byte/mm.......................................................................................................................24
4. 32-byte with timestamp...................................................................................................24
5. ID-0 output .....................................................................................................................24
6. 8-byte/cm........................................................................................................................24
7. Output with Device ID ....................................................................................................25
Appendix II Serial communication protocol....................................................................................26
1. Version information ID_GET_VERSION=0x01..............................................................26
2. System software restore ID_SOFT_RESET=0x02...........................................................26
3. Output frequency ID_SAMPLE_FREQ=0x03.................................................................26
4. Trigger mode ID_SAMPLE_TRIG=0x04........................................................................27
5. Output format setting ID_OUTPUT_FORMAT=0x05.....................................................27
6. Baud rate setting ID_BAUD_RATE=0x06 ......................................................................27
7. Enable/disable output ID_OUTPUT_EN=0x07...............................................................28
8. Enable/disable checksum comparison ID_FRAME_CHECKSUM_EN=0x08 .................28

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page6
9. I2C slave machine address configuration ID_I2C_SLAVE_ADDR=0x0B.......................28
10. Restore default setting ID_RESTORE_DEFAULT=0x10 ................................................29
11. Save current setting ID_SAVE_SETTINGS=0x11...........................................................29
12. Output product bar code ID_READ_MANU_BIN=0x12 ................................................29
13. Get full-length version number ID_GET_FULL_VERSION=0x14 .................................30
14. Amp threshold setting ID_AMP_THRESHOLD=0x22 ...................................................30
15. Switch between Single Frequency and Dual Frequency ID_ DEALIAS_EN =0x29.........30
16. Timestamp synchronization ID_TIMESTAMP_SYNC =0x31.........................................31
17. Enable/disable Power saving mode (ECO) ID_LOW_CONSUMPTION=0x35 ...............31
18. Filter Setup ID_FILTER_BIT_MAP=0x39 .....................................................................31
19. Distance limit setting ID_DIST_LIMIT=0x3A................................................................32
20. Enable/disable on-off mode ID_ON_OFF_MODE=0x3B ...............................................32
21. Read config by id ID_GET_CONFIG_PARA=0x3F .......................................................32
22. Ultra-low Power Mode ID_ ULTRA_LOW_POWER_MODE=0x58 ..............................33
23. Frequency Calibration ID_FREQ_CNT_CALIB=0x59 ...................................................33
Appendix III I2C register table........................................................................................................34

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page7
1 Revisions
Version No.
History
Date
A00
Original
2020.1.15
A03
1. Old serial port formats are removed.
2. Module size and related pictures are updated.
3. More description of function.
4. I2C interface is now available.
5. Power supply voltage up to 3.7V-5.2V is now supported.
2020.3.15
A05
1. Removed “Enable/disable low sample rate mode
ID_LOW_SAMPLE_RATE=0x3E”.
2. Changed the definition of I2C register 0x25: 0x00 – LiDAR off, 0x01 –
LiDAR on.
3. Changed the description of I2C register. Users should make sure that
firmware version is above V1.0.7 when using I2C communication.
4. Added the description on Amp with respect to ambient light
overexposure.
5. Added Ultra-low Power Mode.
6. For I2C register 0x2E-0X31, changed the units of distance limit from
centimeter to millimeter.
7. Added description on the Single Frequency Mode.
8. Added filter setup commands.
9. Added device ID into the output format.
2020.7.23
2 Cautions
2.1 About document
This manual provides all essential information you may need during the usage of this product.
Please read this manual carefully before using this product and make sure that you fully
understand the contents of the manual.

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page8
2.2 About product
The product can only be maintained and repaired by qualified professionals, and only original
spare parts are permitted to use for performance and safety reasons.
This product DOES NOT have polarity and over-voltage protection at all. Please wire and
supply power according to the instructions.
The working temperature of the product is from -10℃ to 60℃, please do not use it outside
this temperature range to avoid risk and damage.
The storage temperature of the product is from -20℃ to 75℃, please do not store it outside
this temperature range to avoid risk and damage.
For safety and performance, please DO NOT open the product casing or remove the IR-pass
filter.
2.3 Common errors and other notes
Detecting object with high reflectivity, such as mirrors, smooth floor tiles, and calm milk
liquid.
Blocking the product with any transparent objects, such as water or glasses.
The product’s lens may be covered by dusts or dirt which may affect results, so please keep
the lens clean.
The exposed circuit board is electrostatic sensitive. Please do not touch the circuit board of
the product barehanded. Please use ESD wrist strap or antistatic gloves to ground yourself if
any operation is necessary; Otherwise, the product may be damaged by static electricity.
3 Principle description and key parameters
3.1 Ranging Principle
TF-Luna is using Time of Flight (ToF) principle to measure the distance and it periodically emits
near infrared modulated waves. TF-Luna calculates the time by measuring the phase difference
between the original wave and the reflection wave and uses that time to get relative distance, as
shown in Figure 1.

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page9
Figure 1 Schematics of ToF Principle
3.2 Basic Characteristic Parameters
Table 1 Parameters specification of TF-Luna
Description
Parameter value
Operating range
0.2m~8m①
Accuracy
±6cm@ (0.2-3m)
±2%@ (3m-8m)
Measurement unit
cm (Default)
Range resolution
1cm
FoV
2°②
Frame rate
1~250 Hz ( adjustable ) ③
①Operating range is measured indoor based on a standard whiteboard with reflectivity 90%.
②This is theoretical value, real value may be different.
③100 Hz is default and only any factor (500/n, n can be any integer in [2, 500]) of 500Hz is available.
3.3 Repeatability
TF-Luna's ranging accuracy is positively correlated with the strength value (amp) and negatively
correlated with the output frame rate (frequency). The tables below show the standard deviation (STD)
using 100Hz output rate. These values are for reference only; various testing environments may give
different results.
Table 2 STD Amp correlation
Amp
100
200
400
1000
≥2000
STD
3cm
3cm
2cm
1cm
0.5cm

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page10
Table 3 STD Dist correlation with 90% diffuse reflectance object
Dist
200cm
400cm
600cm
800cm
Std
0.5cm
1cm
1.5cm
2cm
3.4 Ranging Characteristics
TF-Luna minimizes the impact of external environment on ranging performance by optimizing light
path and algorithm.
TF-Luna’s ranging blind zone is 20 cm. Any distance output less than 20 cm is unreliable. The
operating range of black and white targets is different:
The operating range of TF-Luna detecting black target with 10% reflectivity is 0.2-2.5m; the
operating range of TF-Luna detecting white target with 90% reflectivity is 0.2-8m.
The ranging data is reliable only if the reflection surface fully covers the light spot, so the diameter
of the object must at least the same as the diameter of the light spot, and that diameter depends on
FoV of TF-Luna. The minimum diameter of the object surface can be determined by the following
formula:
d = 2 ∗ D ∙ tanβ
In the formula, d represents the minimum diameter, D is the distance of the object, and β is the
half FoV of TF-Luna. Common values are shown in Table 4 for your convenience:
Table 4 Distance and minimum diameter
Distance (D)
1m
2m
3m
4m
5m
6m
7m
8m
Minimum diameter (d)
3.5cm
7cm
10.5cm
14cm
17.5cm
21cm
24.5cm
28cm
If the light spot reaches two objects with different distances as Figure 2, the output distance value
(Dist) will be abnormal, which may cause error for high-accuracy applications. Please try to avoid this
situation for better accuracy and performance.

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page11
Figure 2 Detecting two objects at different location
4 Appearance and Structure
4.1 Appearance
Figure 3 TF-Luna appearance and size drawing
5 Electrical Characteristics
Table 5 Major Electrical Parameters of TF-Luna
Description
Value range
Power supply voltage
3.7V-5.2V
Average current
≤70mA
Peak current
150mA
Power consumption
≤350mW
Communication signal level
LVTTL (3.3V)
This product has no overvoltage nor polarity protection, so please make sure that the product is
well connected, and the power supply voltage is inside the given range.

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page12
6 Functional Descriptions and Configuration
Figure 4 TF-Luna’s pin numbers
6.1 Description about Line Sequence and Connection
Table 6 The Function and Connection Description of Each Pin
No.
Function
Description
1
+5V
Power supply
2
RXD/SDA
Receiving/Data
3
TXD/SCL
Transmitting/Clock
4
GND
Ground
5
Configuration Input
Ground: I2C mode
Disconnected/3.3V: Serial
port Communications mode
6
Multiplexing output
On/off mode: Output
I2C mode: Data ready signal
6.2 Serial Port Communication Protocol
Serial port communication starts when pin 5 is disconnected or connected to 3.3v. It will set
TF-Luna receiving RXD on pin 2 and sending TXD on pin 3. The serial port communication protocol is
defined as follows: 8 data bits, 1 stop bit with no parity check and default baud rate of 115200 bps.
Serial port communication protocol data byte format:
byte
0
1
2
3~Len-2
Len-1
Description
Head(0x5A)
Len
ID
Payload
Checksum
Head: Fixed 0x5A.
Len: The length of bytes from the head byte to check-sum at the end, and it has to be in between
4 to 255.

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page13
ID: Indicates how to parse the payload data.
Payload: Payload data segment, optional.
Checksum: The lower 8 bytes of the sum from Head to Payload.
Please check Appendix II Serial communication protocol for more information.
Note: TF-Luna does not enable checksum check for sending data frames by default, that is, the
Checksum at the end of the sending frame can be filled with any value.. Thus, ANY value is acceptable
on the Checksum byte, unless checking of those bytes is required. Please check “Enable/disable
checksum comparison ID_FRAME_CHECKSUM_EN=0x08” in Appendix II Serial communication
protocol to enable the feature.
The instruction makes change immediately after sending, but the current setting is not saved and
will be lost after reboot. User must use “Save current setting ID_SAVE_SETTINGS=0x11” to save the
change. The full save-current-setting hexadecimal sequence is 5A 04 11 00 in this case.
6.3 I2C Communication
When pin 5 is connected to ground, TF-Luna enters I2C mode, then its pin 2 is used as SDA data
and pin 3 is the SCL clock sending data. TF-Luna supports up to 400kps clock speed as slave machine
and its default address is 0x10. For more information about I2C register table refer to Appendix III I2C
register table.
Note: In this document, the address of I2C slave device is a 7-bit value with value range [0x08,
0x77] ([0, 119] in decimal). For the first byte after I2C releases a start signal, the 7-bit address should be
shifted leftward for one bit (i.e. multiplied with 2), and then filled with the read-write sign on the
lowest bit. For TF-Luna, the default address of slave device is 0x10, the address for write operations is
0x20, and the address for read operations is 0x21.
Write register timing:
Start
Slave Addr
W
Ack
Register Addr
Ack
Data1
Ack
…
DataN
Ack
Stop
Read register timing:
Start
Slave Addr
W
Ack
Register Addr
Ack
Stop
Start
Slave Addr
R
Ack
Data1
Ack
…
DataN
Nack
Stop

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page14
Note that in the read register sequence, the host can directly generate the second Start signal
without generating the first Stop signal. The last Nack can also be an Ack signal.
In the continuous ranging mode, the host must monitor pin 6 for synchronous signal and initiate
the read data operation in time. Otherwise, it may cause an error by reading and updating the data
register at the same time. In multi-machine bus mode, use command to trigger reading is strongly
recommended.
Figure 5 Timing of reading data register in I2C mode
Pin 6 is normal low level and it switches to high as soon as the data is updated. It switches to low
level only if a read operation on any register is done. Therefore, I2C host must read the register when
receive a high level on pin 6 in the continuous ranging mode. As the figure has shown above, the first
result in red is unreliable and the rest two in green are accurate.
After a write operation on the I2C register, it takes TF-Luna some time to process. If users need to
read the value from the register for validation purposes, we recommend waiting for 100ms after the
write operation, prior to the next read operation.
6.4 Basic Data Output
TF-Luna normally provides these data below:
⚫Distance (Dist): Default in centimeters.
⚫Signal strength (Amp): Distance value is unreliable when receiving signal is overexposed (Amp
= 0xFFFF) or too low (Amp < 100). Normally, Amp value should not be above 30000. When
Amp is above 32768, it indicates that TF-Luna has detected an ambient light overexposure, for
instance, when it faces the sun in outside.
⚫Chip Temperature (Temp): Celsius degree = Temp/8 - 256℃
TF-Luna supports various serial format, please check Appendix I Serial port output format for
more information, and the default setting is 9-bytes/centimeter. Format setting is in “Output format

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page15
setting ID_OUTPUT_FORMAT=0x05” section.
6.5 Continuous Ranging Mode
TF-Luna will keep tracking the distance 500 times per second, but as the customized output
frequency is lower, the output may take the average. For instance, if the output frequency is 100Hz as
default, then the output values are the average (arithmetic mean) of 5 previous range data. Therefore,
lower output frequency gives less time of the averaging process as well as less fluctuation of the output.
The highest output frequency that TF-Luna supports is 250Hz (output_frequency ≤ 250Hz), and it must
be 500/n Hz (where n is an integer that is in the range [2, 500]). Thus, all supported values of output
frequency are: 250Hz, 166Hz, 125Hz, 100Hz, …, 2Hz, 1Hz. User can change the output frequency using
“Output frequency ID_SAMPLE_FREQ=0x03”.
6.6 Trigger Mode
TF-Luna enters trigger mode if the output frequency is set to 0 with “Output frequency
ID_SAMPLE_FREQ=0x03”. In this mode, TF-Luna stops measuring and outputting unless it is triggered
by “Trigger mode ID_SAMPLE_TRIG=0x04” — in other words, TF-Luna measures and output once as
soon as it receives the hexadecimal byte string 5A 04 04 00.
6.7 On/off Mode
On/off mode is designed from those users who only need to detect the existence of an object.
TF-Luna can start this mode using “Enable/disable on-off mode ID_ON_OFF_MODE=0x3B” and then
shows result through pin 6. Figure 6 below shows how the mode works when a high level is set to
represent an object is detected.
Figure 6 On/off mode that high level means closer
Zone value: If an object is detected closer than Dist, then Pin 6 outputs high-level, but only if an
object is detected farther than Dist + Zone, then Pin 6 outputs low-level. When zone is set to 0, pin 6
may output up and down cause by fluctuation of the measuring when the real distance happens to be

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page16
the same as Dist. That is why a proper zone value is needed to help avoid this situation by having a
hysteretic interval.
Delay is also supported to avoid inaccurate jumping output. Pin 6 changes its output depends on
the Dist value condition and the time it lasts. Delay1(ms) and Delay2(ms) determine how long that
approaching changes and leaving changes should wait after Dist value is already over the line.
Note: Since the Dist value is set to 0 under factory setting when no object is detected and Amp is
too low, then pin 6 may have false output in the on/off mode. Please follow the instructions in 6.8 Amp
to set the over-threshold value greater than Dist + Zone to avoid false output.
6.8 Amp Threshold
The distance calculation may get false result if the Amp value is too low, so TF-Luna set the Dist
value to dummy_dist(Default 0) when Amp is lower than amp_threshold (Default 100). If a user needs
to change the Amp threshold value, please follow instructions in “Amp threshold setting
ID_AMP_THRESHOLD=0x22”. Note that the final Amp threshold in TF-Luna is 10 times the value you
send to it.
6.9 Distance Limit
TF-Luna has a default maximum and minimum distance output: [min, max] = [0cm, 900cm].
User can change the output limits using “Distance limit setting ID_DIST_LIMIT=0x3A”.
Note: Any distance value lower than 20cm or greater than 800cm may be unreliable.
6.10 Power Saving Mode
The power consumption of TF-Luna is determined by two factors: the light source driving current
and the light-emitting duty cycle.
TF-Luna adjusts the driving current of the light source adaptively to achieve the purpose of large
dynamic range adapting to different distances and different reflectivity targets. When the signal
strength is too high, it will automatically switch to low gear current work. On the contrary, when the
signal strength is too low, it will automatically switch to high gear current work. The higher the current
gear is, the greater the power consumption will be.
Refer to "6.5 Continuous Ranging ". In continuous ranging mode, TF-Luna always emits light with
the highest duty cycle, which does not change with the output frequency. Therefore, when TF-Luna is in
continuous working mode and the current gear is at the highest gear, the power consumption is the
largest. When the power is supplied with 5V, the power consumption is about 350mW.

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page17
The user can change TF-Luna's luminous duty cycle in two ways. The first is to use the command
trigger mode. TF-Luna does not emit light when it does not receive a ranging command. At this time,
the power consumption is about 42.5mW (5V power supply). The actual power consumption is
determined by the frequency of the command trigger. Another way is to enable the low power
consumption mode provided by TF-Luna. The internal working mechanism of this mode is the same as
the command trigger mode, except that the trigger signal is automatically generated internally by
TF-Luna. The user can set the TF-Luna to enter the low-power mode through the "Enable/disable
Power saving mode (ECO) ID_LOW_CONSUMPTION=0x35" instruction.
To ensure the internal working sequence of TF-Luna, the maximum output frequency of low power
consumption mode is 10Hz. The following table lists the reference values of the average power
consumption at different operating frequencies in the low power mode when the power supply is 5V.
The actual power consumption may be affected by the ambient temperature or the supply voltage, and
may differ from the reference value.
Power saving frequency
Avg current(mA)
Avg power (mW)
1Hz
8.85
44.25
2Hz
9.2
46
3Hz
9.55
47.75
4Hz
9.9
49.5
5Hz
10.25
51.25
6Hz
10.6
53
7Hz
10.95
54.75
8Hz
11.3
56.5
9Hz
11.65
58.25
10Hz
12
60
6.11 Ultra-low Power Mode
In order to further reduce power consumption, TF-Luna offers an Ultra-low Power Mode. In this
mode, MCU enters sleep mode, and the standby power consumption of TF-Luna is about 1.5mW at this
time. However, when MCU sleeps, it is not able to automatically awake as Low Power Mode is activated.
Therefore, we need to change the voltage of Pin 2 to wake it up.

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page18
6.11.1 Ultra-low Power Mode with Serial Port Communication
(1) Turn on Ultra-low Power Mode
The command “Ultra-low Power Mode ID_ ULTRA_LOW_POWER_MODE=0x58” is used
to turn on Ultra-low Power Mode. TF-Luna will stop serial port outputting data once the
command is delivered. However, it will not enter the mode immediately. Users should
send “Save current setting ID_SAVE_SETTINGS=0x11” to save current settings and then
send “System software restore ID_SOFT_RESET=0x02” to reset system. Later on, TF-Luna
will enter the Ultra-low Power Mode. Since the settings have been saved, TF-Luna will
enter directly into this mode on next boot-up.
(2) Bring up Range-finding
Users can wake up TF-Luna and make it perform range-finding once by sending a random
byte to the serial port. TF-Luna will send back the range-finding result in a specific format,
and then enter Ultra-low Power Mode once again. The following graph shows the case in
which the baud rate is 115200 with 9-byte output format. The awakening lasts about
8.5ms.
Figure 7 Time sequence of Ultra-low Power Mode with serial port communication
(3) Turn off Ultra-low Power Mode
Users cannot exit the Ultra-low Power Mode directly, because the serial port
communication module is disabled. TF-Luna can only receive serial port commands
during short intervals when it is awake. Therefore, users need to continuously send the
command “Ultra-low Power Mode ID_ ULTRA_LOW_POWER_MODE=0x58” to disable
the Ultra-low Power Mode untill TF-Luna responds. After that, users should send “Save
current setting ID_SAVE_SETTINGS=0x11” command to save current settings.
(4) Estimation of Power Consumption

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page19
TF-Luna consumes 1.5mW during sleep and on average 260mW during awakening. The
awakening will last about 8.5ms. Based on the information, it consumes on average
3.7mW if we wake it up every second and on average 1.72mW if we wake it up every ten
seconds.
6.11.2 Ultra-low Power Mode with I2C communication
(1) Turn on Ultra-low Power Mode
In order to turn on and save Ultra-low Power Mode, users need to write three
consecutive bytes [0x01, 0x01, 0x02] to the address 0x1F.
(2) Bring up Range-finding
Users can attempt reading any one of valid or invalid register addresses (which will not
make us receive ACK from the slave device). In this way, TF-Luna will detect the change of
voltage on Pin 2 and thus it will be awaken. TF-Luna will perform range-finding once upon
each awakening, and update the result on the register. It will not fall back to sleep mode
until the user performs a read-register operation.
Figure 8 Time sequence of Ultra-low Power Mode with I2C communication
(3) Turn off Ultra-low Power Mode
Reading the register will make TF-Luna enter sleep mode once again, therefore, in order
to turn off the Ultra-low Power Mode, users need to write three consecutive bytes [0x00,
0x01, 0x02] to the address 0x1F after the awakening. It should be done no sooner than
6ms after the awakening).
(4) Estimation of Power Consumption
TF-Luna consumes 1.5mW during sleep and on average 200mW during awakening.

SJ-PM-TF-Luna A05 Product Manual
Benewake (Beijing) Co. Ltd.
Page20
Range-finding in an awakening period takes about 12ms, and awaiting users’
read-operation consumes about 42.2mW. Assuming it waits for 5ms, based on the
information, it consumes on average 4.1mW if we wake it up every one second, and on
average 1.76mW if we wake it up every ten seconds.
6.11.3 Caveats
Users should not send any setup command in the Ultra-low Power Mode, because MCU will be in
sleep so that it may not respond to users’ command. In Ultra-low Power Mode, it is only allowed to
bring up range-finding, or to turn off the mode. All other operations should be performed after the
mode is turned off.
6.12 Single Frequency Mode
TF-Luna obtains distance measurement from phase shift of the sinusoidal modulated laser light.
The model is subjected to the “periodic distance” problem. The periodic distance for TF-Luna is 15
meters, when working in Single Frequency Mode. However, when the distance is beyond 15 meters, the
measured value starts from zero again. Assuming there is a highly reflective object at 16 meters;
TF-Luna may mistake it as at 1 meter. In order to extend the periodic distance, TF-Luna sets the default
work mode to Dual Frequency Mode. The periodic distance in such a mode is over 65 meters, far wider
than the sensor’s measuring range. In this way, the “overshoot” problem is addressed.
However, in Dual Frequency Mode, the range-finding algorithm requires higher stability on sensor
data. When the signal is weak (AMP lower than 100), the low data stability produces errors in the range
algorithm, and thus yields anomalies in output range values. The error can reach tens of meters. In
some application scenarios, the target reflection rate is low so that AMPs lower than 100 are needed. In
this case, users can set TF-Luna to Single Frequency Mode. In Single Frequency Mode, when AMP is
lower than 100, the stability of range data is low. Even so, it is not allowed to have significant anomalies
on data values. Meanwhile, users should make sure their application scenarios are not subjected to the
overshoot problems.
6.13 Additional notes
Please check Appendix II Serial communication protocol for more options, such as version ID
report, system software restore, baud rate configuration, etc.