Version: 0.1.4
Release date: 12.03.2017
Changelog: see git log

This is a library for Linux that helps interface with ST's VL53L0X time-of-flight distance sensor. The library makes it simple to configure the sensor and read range data from it via I²C.

Additionally it provides support for managing multiple sensors connected to the same bus by managing hardware standby of individual sensors via their XSHUT pins, see multiple sensors section

• Development status
• Supported platforms
• Used libraries/dependencies
• Usage
  • Hardware
    • Connections
      • Odroid C2
      • Raspberry Pi
  • Software
    • Building
    • Installation
      • Debian
      • Archlinux
      • Manual (others)
    • Using the library
    • Building your code using the library
      • Using system-installed library and plain GCC
      • Using system-installed library and CMake
      • Using library from userspace
  • Multiple sensors
• Examples
  • Single ranging mode, single sensor
  • Single ranging mode, multiple sensors
  • Continuous ranging mode, multiple sensors
• ST's VL53L0X API and this library
• Library reference
• Special thanks

• WORKING
• Wire.h replaced with WiringPi
• Multiple sensors support added
• Hardware standby (XSHUT) management support added (part of multiple sensors support)
• Single sensor: tested and working (examples/single)
• Multiple sensors: tested and working (examples/singleMultipleSensors)
• Continuous measurement: tested and working (examples/continuousMultipleSensors)
• Code style consistency improved
• Documentation moved to header (why would you want them with source?)
• Other minor improvements

TODO:

• Improve/add missing documentation
• More examples/tests (?)
• Better error handling/reporting (?)

• Odroid C2 - main target board
• Odroid C1/XU3/XU4 - as supported by linked WiringPi fork
• Raspberry Pi (any) - as supported by base WiringPi library
• Others - possible but unsure

• WiringPi (my fork) - for both I²C and GPIO connectivity. My forked version adds support for Odroid boards and for writing block data to I²C

A VL53L0X carrier can be purchased from Pololu's website. Before continuing, careful reading of the product page as well as the VL53L0X datasheet is recommended.

Important notes on hardware:

• XSHUT is connected via pull-up resistor to VIN, therefore the sensor can be powered from GPIO even if VIN is disconnected
• Even putting the sensor to hardware standby (XSHUT low, VIN connected) will reset its address (see Multiple sensors secton on why that's important)

Example connection:

           Odroid C2   VL53L0X board
--------------------   -------------
 3.3V Power (Pin #1) - VIN
   I2CA_SDA (Pin #3) - SDA
   I2CA_SCL (Pin #5) - SCL
GPIOX.BIT21 (Pin #7) - XSHUT
     Ground (Pin #9) - GND

Of course, you can also use I2CB_SDA/SCL and any other GPIOX and Ground pins, see Hardkernel's page for pins' description.

      Raspberry Pi 3   VL53L0X board
--------------------   -------------
 3.3V Power (Pin #1) - VIN
       SDA1 (Pin #3) - SDA
       SCL1 (Pin #5) - SCL
  GPIO_GCLK (Pin #7) - XSHUT
     Ground (Pin #9) - GND

cd build/release
cmake ../..
make

Notes:

If WiringPi library is not installed system wise, you can specify its location on build-time.
It may be specified via ENV (WIRINGPI_DIR="/path/to/wiringpi/dir" cmake) or via cmake's definition (cmake -D WIRINGPI_DIR="/path/to/wiringpi/dir").

CMake will try to force gcc/g++-6 usage but will silently fallback to default system compiler if these are not found.

Note: you can include and link this library in userspace, see relevant section

Note2: there are (or will be) pre-built packages for Debian (and derivatives like Ubuntu) and Archlinux in Github's 'release' section. You can download proper package from there and skip to installation via package manager (last step in instructions below).

cd build/release
cmake ../..
make
cpack -G DEB
sudo dpkg -i vl53l0x-linux-*.deb

cd build/archlinux
makepkg
sudo pacman -U vl53l0x-linux-*.pkg.*

cd build/release
cmake ../..
make
sudo make install

• Include <VL53L0X.h>
• Create instance of VL53L0X class
• Call .init()
• (Optional) set timing budget etc
• For single range reading:
  • Call .readRangeSingleMillimeters()
  • Check for possible timeout using .timeoutOccurred() (returned range value will be at maximum of 65535)
• For continuous ranging:
  • Call .startContinuous()
  • Read rangings using .readRangeContinuousMillimeters()
  • Check for timeout (like in single ranging)
  • End with .stopContinuous()

See examples section for reference and Multiple sensors section for instructions how to use multiple sensors at once.

Link against vl53l0x, e.g.:

g++ -lvl53l0x your_code.cpp

find_package (vl53l0x REQUIRED)
target_link_libraries (your_target LINK_PUBLIC vl53l0x)

Add VL53L0X.h to include path, link against built libvl53l0x.so, e.g.:

g++ -I/path/to/VL53L0X.h -l/path/to/libvl53l0x.so your_code.cpp

Multiple sensors can be used easily by connecting them all to the same I²C bus and connecting their XSHUT pins to free GPIO pins of your board.

Note that even putting the sensor to hardware standby (XSHUT low) will reset its address! Thus, the workflow is as such:

• disable (power off) all sensors
• enable (power on) first sensor
• set its address
• enable second sensor, set its address
• ...and so on

That translates to following steps within your code:

• initialize GPIO connectivity by calling wiringPiSetup() or wiringPiSetupGpio() and ensure the pins are in output mode (pinMode(pin, OUTPUT))
• pass XSHUT GPIO pin number to sensor object constructor (VL53L0X(pin))
• disable all sensors either by calling their .powerOff() methods or by writing low value to their GPIO pins (digitalWrite(pin, LOW))
• initialize sensors one-by-one and set different address for each one before initializing the next one

After that, reading range values from sensors is just like with single one. See examples/singleMultipleSensors.cpp and examples/continuousMultipleSensors.cpp for reference.

Build examples with:

cd build/release
cmake ../..
make examples

and run with

./examples/single
./examples/singleMinimal
./examples/singleMultipleSensors
./examples/continuousMultipleSensors

examples/singleMinimal.cpp shows the minimal working example.

examples/single.cpp shows how to use a single sensor in single ranging mode in more detail and with proper commentary on what's going on.

examples/singleMultipleSensors.cpp shows how to use multiple sensors at once in single ranging mode.

examples/continuousMultipleSensors.cpp shows how to use continuous ranging mode (with back-to-back measurements) while using multiple sensors at once.

Note: in my experiments on Odroid C2 board with Linux-RT kernel, I've managed to run 6 sensors at once with stable frequency of more than 50Hz!

TODO: rewrite this to match this version of the library (Linux not Arduino)

Most of the functionality of this library is based on the VL53L0X API provided by ST (STSW-IMG005), and some of the explanatory comments in the code are quoted or paraphrased from the API source code, API user manual (UM2039), and the VL53L0X datasheet. For more explanation about the library code and how it was derived from the API, see the comments in VL53L0X.cpp.

This library is intended to provide a quicker and easier way to get started using the VL53L0X with an Arduino-compatible controller, in contrast to customizing and compiling ST's API for the Arduino. The library has a more streamlined interface, as well as smaller storage and memory footprints. However, it does not implement some of the more advanced functionality available in the API (for example, calibrating the sensor to work well under a cover glass), and it has less robust error checking. For advanced applications, especially when storage and memory are less of an issue, consider using the VL53L0X API directly.

This section was not yet updated to match Linux version of the library - see header file for updated descriptions!

• uint8_t last_status
  The status of the last I²C write transmission. 0 for success, errno for errors (you can use strerrno from to see error description)

• VL53L0X()
  Constructor.

• void setAddress(uint8_t new_addr)
  Changes the I²C slave device address of the VL53L0X to the given value (7-bit).

• uint8_t getAddress()
  Returns the current I²C address.

• bool init(bool io_2v8 = true)
  Iniitializes and configures the sensor. If the optional argument io_2v8 is true (the default if not specified), the sensor is configured for 2V8 mode (2.8 V I/O); if false, the sensor is left in 1V8 mode. The return value is a boolean indicating whether the initialization completed successfully.

• void writeReg(uint8_t reg, uint8_t value)
  Writes an 8-bit sensor register with the given value. Register address constants are defined by the REGISTER_ADDRESSES enumeration type in VL53L0X.h.
  Example use: sensor.writeReg(VL53L0X::SYSRANGE_START, 0x01);

• void writeReg16Bit(uint8_t reg, uint16_t value)
  Writes a 16-bit sensor register with the given value.

• void writeReg32Bit(uint8_t reg, uint32_t value)
  Writes a 32-bit sensor register with the given value.

• uint8_t readReg(uint8_t reg)
  Reads an 8-bit sensor register and returns the value read.

• uint16_t readReg16Bit(uint8_t reg)
  Reads a 16-bit sensor register and returns the value read.

• uint32_t readReg32Bit(uint8_t reg)
  Reads a 32-bit sensor register and returns the value read.

• void writeMulti(uint8_t reg, uint8_t const * src, uint8_t count)
  Writes an arbitrary number of bytes from the given array to the sensor, starting at the given register.

• void readMulti(uint8_t reg, uint8_t * dst, uint8_t count)
  Reads an arbitrary number of bytes from the sensor, starting at the given register, into the given array.

• bool setSignalRateLimit(float limit_Mcps)
  Sets the return signal rate limit to the given value in units of MCPS (mega counts per second). This is the minimum amplitude of the signal reflected from the target and received by the sensor necessary for it to report a valid reading. Setting a lower limit increases the potential range of the sensor but also increases the likelihood of getting an inaccurate reading because of reflections from objects other than the intended target. This limit is initialized to 0.25 MCPS by default. The return value is a boolean indicating whether the requested limit was valid.

• float getSignalRateLimit()
  Returns the current return signal rate limit in MCPS.

• bool setMeasurementTimingBudget(uint32_t budget_us)
  Sets the measurement timing budget to the given value in microseconds. This is the time allowed for one range measurement; a longer timing budget allows for more accurate measurements. The default budget is about 33000 microseconds, or 33 ms; the minimum is 20 ms. The return value is a boolean indicating whether the requested budget was valid.

• uint32_t getMeasurementTimingBudget()
  Returns the current measurement timing budget in microseconds.

• bool setVcselPulsePeriod(vcselPeriodType type, uint8_t period_pclks) Sets the VCSEL (vertical cavity surface emitting laser) pulse period for the given period type (VL53L0X::VcselPeriodPreRange or VL53L0X::VcselPeriodFinalRange) to the given value (in PCLKs). Longer periods increase the potential range of the sensor. Valid values are (even numbers only):

  Pre: 12 to 18 (initialized to 14 by default)
  Final: 8 to 14 (initialized to 10 by default)

  The return value is a boolean indicating whether the requested period was valid.

• uint8_t getVcselPulsePeriod(vcselPeriodType type)
  Returns the current VCSEL pulse period for the given period type.

• void startContinuous(uint32_t period_ms = 0)
  Starts continuous ranging measurements. If the optional argument period_ms is 0 (the default if not specified), continuous back-to-back mode is used (the sensor takes measurements as often as possible); if it is nonzero, continuous timed mode is used, with the specified inter-measurement period in milliseconds determining how often the sensor takes a measurement.

• void stopContinuous()
  Stops continuous mode.

• uint16_t readRangeContinuousMillimeters()
  Returns a range reading in millimeters when continuous mode is active.

• uint16_t readRangeSingleMillimeters()
  Performs a single-shot ranging measurement and returns the reading in millimeters.

• void setTimeout(uint16_t timeout)
  Sets a timeout period in milliseconds after which read operations will abort if the sensor is not ready. A value of 0 disables the timeout.

• uint16_t getTimeout()
  Returns the current timeout period setting.

• bool timeoutOccurred()
  Indicates whether a read timeout has occurred since the last call to timeoutOccurred().

• Pololu for both the sensor breakout board and their Arduino library this project bases upon
• Drogon for his awesome WiringPi library, see notes in my fork
• ST for making this great sensor!