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UM2884
User manual
A guide to using the VL53L5CX multizone Time-of-Flight ranging sensor with
wide field of view Ultra Lite Driver (ULD)
Introduction
The purpose of this user manual is to explain how to handle the VL53L5CX Time-of-Flight (ToF) sensor, using the ultra lite driver
(ULD) API. It describes the main functions to program the device, the calibrations, and the output results.
The VL53L5CX is a state of the art, ToF, multizone ranging sensor enhancing the ST FlightSense product family. Housed in
a miniature reflowable package, it integrates a SPAD array, physical infrared filters, and diffractive optical elements (DOE) to
achieve the best ranging performance in various ambient lighting conditions with a range of cover glass materials.
Multizone distance measurements are possible up to 8x8 zones with a wide 63 ° diagonal field of view (FoV) which can be
reduced by software. Each zone of the VL53L5CX measures the distance of the target up to 4 meters, at a maximum frequency
of 60 Hz.
Thanks to ST Histogram patented algorithms, the VL53L5CX is able to detect different objects within the FoV. The Histogram
also provides immunity to cover glass crosstalk beyond 60 cm.
Figure 1.
VL53L5CX sensor module
References
1.
VL53L5CX datasheet (DS13754)
UM2884 - Rev 2 - August 2021
www.st.com
For further information contact your local STMicroelectronics sales office.
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Summary of Contents for ST UM2884
- Page 1 (ULD) API. It describes the main functions to program the device, the calibrations, and the output results. The VL53L5CX is a state of the art, ToF, multizone ranging sensor enhancing the ST FlightSense product family. Housed in a miniature reflowable package, it integrates a SPAD array, physical infrared filters, and diffractive optical elements (DOE) to achieve the best ranging performance in various ambient lighting conditions with a range of cover glass materials.
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Page 2: Acronyms And Abbreviations
Kilo-count per second per spad (unit used to quantify the Kcps/SPAD number of photons into the SPAD array) random access memory serial clock line serial data SPAD single photon avalanche diode Time-of-Flight ultra lite driver VCSEL vertical cavity surface emitting diode Xtalk crosstalk UM2884 - Rev 2 page 2/19... -
Page 3: Functional Description
The VL53L5CX system is composed of a hardware module and the ultra lite driver software (VL53L5CX ULD) running on a host (see figure below). The hardware module contains the ToF sensor. ST delivers the software driver which is referred to in this document as "the driver". This document describes the functions of the driver which are accessible to the host. -
Page 4: Schematics And I2C Configuration
Pull up the LPn pin of the device not being reprogrammed. All devices should now be available on the I2C bus. Repeat the above steps for all the VL53L5CX devices in the system that require a new I2C address. UM2884 - Rev 2 page 4/19... -
Page 5: Package Content And Data Flow
The user also needs to implement two files located in the /Platform folder. The proposed platform is an empty shell, and must be filled with dedicated functions. Note: Platform.h file contains mandatory macros to use the ULD. All the file content is mandatory to correctly use the ULD. UM2884 - Rev 2 page 5/19... -
Page 6: Calibration Flow
The calibration is performed using function vl53l5cx_calibrate_xtalk(). This function can be used at any time. However, the sensor must be initialized first. The following figure represents the Xtalk calibration flow. Figure 6. Xtalk calibration flow UM2884 - Rev 2 page 6/19... -
Page 7: Ranging Flow
The following figure represents the ranging flow used to get measurements. Xtalk calibration and optional function calls must be used before starting the ranging session. The get/set functions cannot be used during a ranging session, and 'on-the-fly' programming is not supported. Figure 7. Ranging flow using VL53L5CX UM2884 - Rev 2 page 7/19... -
Page 8: Available Features
Table 2. Minimum and maximum ranging frequencies Resolution Min ranging frequency [Hz] Max ranging frequency [Hz] Ranging frequency can be updated using function vl53l5cx_set_ranging_frequency_hz(). By default, the ranging frequency is set to 1 Hz. UM2884 - Rev 2 page 8/19... -
Page 9: Ranging Mode
Integration time for 4x4 autonomous Figure 9. Integration time for 8x8 autonomous The sum of all integration times + 1 ms overhead must be lower than the measurement period, otherwise the ranging period will be automatically increased. UM2884 - Rev 2 page 9/19... -
Page 10: Power Modes
Figure 10. Example of scene using several sharpener values Sharpener can be changed using function vl53l5cx_set_sharpener_percent(). The allowed values are between 0 % and 99 %. The default is 5 %. UM2884 - Rev 2 page 10/19... -
Page 11: Target Order
For example, the user can run a Xtalk calibration on one single device, and re-use the same calibration data for all other devices. The Xtalk margin can be used to tune the Xtalk correction. The figure below represents the Xtalk margin. Figure 12. Xtalk margin UM2884 - Rev 2 page 11/19... -
Page 12: Detection Thresholds
An ideal combination for low power applications is the use of the motion indicator with Autonomous ranging mode, and detection thresholds programmed on the motion. This allows detection of movement variations in the FoV with minimum power consumption. UM2884 - Rev 2 page 12/19... -
Page 13: Ranging Results
Consequently, the fields will not be declared in the results structure, and the data will not be transferred to the host. The RAM size and I2C size are reduced. To ensure data consistency, ST recommends to always keep ‘number of target detected’ and ‘target status’ enabled. It allows filtering the measurements depending of the target status (refer to Section 5.5 Results... -
Page 14: Getting Ranging Results
To have consistent data, the user needs to filter invalid target status. To give a confidence rating, a target with status 5 is considered as 100 % valid. A status of 6 or 9 can be considered with a confidence value of 50 %. All other statuses are below 50 % confidence level. UM2884 - Rev 2 page 14/19... - Page 15 …) Major error. Usually a timeout error, due to an I2C error. other Combination of multiple errors described above Note: More error codes can be implemented by the host using the platform files. UM2884 - Rev 2 page 15/19...
- Page 16 Revision history Table 6. Document revision history Date Version Changes 21-Jun-2021 Initial release Added Section 5.4 Using raw firmware format 30-Aug-2021 Added new target status 13 in Table 4. List of available target status UM2884 - Rev 2 page 16/19...
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Page 17: Table Of Contents
Results interpretation ............14 UM2884 - Rev 2... - Page 18 Contents ................17 UM2884 - Rev 2...
- Page 19 ST’s terms and conditions of sale in place at the time of order acknowledgement. Purchasers are solely responsible for the choice, selection, and use of ST products and ST assumes no liability for application assistance or the design of Purchasers’...
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