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OPT8241
User Manual
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Texas Instruments OPT8241 User Manual

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OPT8241 Evaluation Module
User's Guide
Literature Number: SBOU155B
October 2015–Revised February 2017
Contents
1 Trademarks......................................................................................................................... 3
2 Introduction......................................................................................................................... 4
3 Safety................................................................................................................................. 5
4 Hardware ............................................................................................................................ 6
4.1 Block Diagram ............................................................................................................ 6
4.2 Design Specifications.................................................................................................... 6
4.3 Sensor Board ............................................................................................................. 7
4.4 Illumination Board....................................................................................................... 10
4.5 Power Supply ........................................................................................................... 10
5 Calibration......................................................................................................................... 12
6 Software............................................................................................................................ 13
6.1 Firmware upgrade ...................................................................................................... 13
7 Known Issues .................................................................................................................... 17
8 Related Documentation From Texas Instruments ................................................................... 17
Revision History.......................................................................................................................... 17
2
Table of Contents
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This document explains the details of the hardware and its usage and provides a basic introduction to the accompanying software. Throughout this document, camera development kit, evaluation module, and the abbreviations CDK and EVM are used interchangeably and are synonymous with the term OPT8241­CDK-EVM.
1 Trademarks
Linux is a registered trademark of Linus Torvalds. Microsoft, Windows are registered trademarks of Microsoft Corporation. All other trademarks are the property of their respective owners.
User's Guide
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OPT8241 Evaluation Module
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OPT8241 Evaluation Module
3
Introduction
2 Introduction
The OPT8241-CDK-EVM showcases TI's high-performance 3D Time-of-Flight (ToF) sensor OPT8241 and the ToF controller OPT9221 (TFC). The EVM is designed to be reconfigurable and modular in order to enable evaluation at a wide range of operating points and is not optimized for any specific application, by default. The accompanying software is designed to enable evaluation of the TI 3D ToF technology at various levels of detail.
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4
OPT8241 Evaluation Module
Figure 1. Components of the EVM
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3 Safety
This Laser Device is designed at Class 1 during normal operation. While the OPT8241-CDK-EVM development boards meet the Class 1 classification requirements under EN/IEC60825-1 2007, users are advised to take the necessary safety caution when using the OPT8241-CDK-EVM. First, examine the board for any damage before the board is powered. Check that the diffusers and diffuser mounts are properly secured on the laser diodes. If there is any damage, stop operating by removing power from the CDK immediately. Opening the laser diffuser assembly may lead to hazardous radiation exposure. Any kind of circuit modification to the board or use of software or firmware other than the recommended EVM tools and firmware provided by TI may lead to violation of class 1 safety limits. Due to the small size and unsuitability for labeling, laser safety related labels are included herein, rather than on the product. Additional safety and manufacturer labels are included in the safety section of the OPT8241-EVM Quick
Start Guide.
This is a class A product as defined by standard EN 61326-1:2013. This product is not intended to be used in domestic establishments and also in establishments that are directly connected to a low-voltage power-supply network that supplies buildings used for domestic purposes. In a domestic environment this product may cause radio interference in which case the user may be required to take adequate measures.
There is no scheduled maintenance required for the OPT8241-CDK-EVM; any servicing and maintenance of this EVM shall be performed only by trained Texas Instruments or TI-appointed trained personnel. Any modification or significant damage to the CDK could potentially cause the CDK to operate outside of the EN/IEC60825 2007 Class 1 classification limits.
Safety
WARNING
Use of controls or adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure.
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Figure 2. Explanatory Label
Figure 3. Certification Label
Figure 4. Hot To Touch
OPT8241 Evaluation Module
5
Hardware
4 Hardware
4.1 Block Diagram
The OPT8241 sensor provides the modulation for the internal pixel array as well as for the external illumination drivers. The illumination drivers in-turn drive the laser illumination on the illumination board. The receiver light is focused using a lens on to the OPT8241 sensor. The depth correlation data obtained by the OPT8241 sensor is digitized and provided to the OPT9221 ToF Controller (TFC), the TFC then processes and provides the distance output for each pixel. A Cypress FX2 chip is used as a USB transceiver to enable PC-based acquisition of data and to control the configuration of the CDK dynamically.
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4.2 Design Specifications
The hardware consists of an assembly of customizable boards. The hardware comes assembled by default and it is not recommended to disassemble the hardware. The individual boards are listed below with their main constituents:
• Sensor board – Sensor, lens holder, lens – TFC, DDR2 memory – USB transceiver
• Illumination board – Lasers , diffuser, diffuser holder – Laser driver
The overall specifications of the CDK hardware are listed in Table 1.
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OPT8241 Evaluation Module
Figure 5. CDK Diagram
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4.3 Sensor Board
The sensor board consists of all interconnects and the corresponding connectors. The illumination board is mechanically held to the sensor board using spacers. The electrical connections between illumination board and sensor board are achieved using a flex cable. The sensor board also provides an extension connector for connecting the boards to an external connector.
Hardware
Table 1. Specifications
Item Specification
Time of Flight Sensor OPT8241
Time of Flight Controller OPT9221
Sensor resolution 320 x 240 (QVGA)
Field of view 74.4 (H) x 59.3 (V)
Frame-rate 12 … 60 fps
Illumination source wavelength 850 nm
Operating range Up to 4 m
Connectivity USB 2.0, micro connector
Cable 1.8 m, Micro USB B-type and standard Male A type
Operating Conditions 0°C to 40°C (Ambient)
CDK Power supply max power 15 Watt
Size 88.8 mm (L) x 60 mm (W) x 24.3 mm (H)
The specifications for the sensor board are listed in Table 2.
Item Specification(*)
Size 88.8 mm (L) x 60 mm (W) x 18.9 mm (H)
Modulation frequency up to 100 MHz
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Figure 6. Sensor Board
Table 2. Sensor Board Specifications
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Hardware
4.3.1 Indicator LEDs
The sensor board has 2 LEDs for indicating various operating states of the board. The master LED indicates the overall status of the board and the TFC LED indicates the status of the Time-of-Flight chipset. The various states of the board are listed in Table 3.
In usual operating conditions, the master LED should be green/cyan and the TFC LED should be blue.
4.3.2 Power Switch
The power switch controls the power to both the sensor and the illumination board. The switch controls are shown in Figure 7.
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Table 3. LED Indicator States
State Master LED TFC LED Status Type
All OK, Streaming OFF Bright Green Blue Info
All OK, Streaming On Cyan X Info
TFC Test Mode Enabled X Off Info
Firmware Upgrade in progress
Firmware Upgrade done Magenta X Info
DC Jack unplugged Dimmed colors X Info
Overtemperature X Magenta Warning
TFC booted, but status failed X Red Error
TFC did not boot Blink (Red) Off Error
Blink
(Magenta)
X Info
4.3.3 Reset Switch
The reset switch resets the entire board without the need to power-cycle the board. As part of the reset process, the reset triggers a USB connect and disconnect on the USB and output data streaming will stop. This may cause the evaluation software on the PC to misbehave if the software is in connected state. Disconnect and connect operations on the software should restore the CDK operation with reset parameters. Figure 8 shows the location of the reset switch.
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OPT8241 Evaluation Module
Figure 7. Power Switch
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4.3.4 Lens Assembly
The lens and the lens mount are both custom parts. To allow the use of standard off-the-shelf lenses, a standard M12 lens mount footprint has been provided.
4.3.5 Tripod Mount
A tripod mount comes assembled with the hardware. The tripod mount can be unscrewed from the assembly, if necessary. Figure 9 shows the tripod mount location and the screws that hold the tripod mount to the rest of the assembly.
Hardware
Figure 8. Reset Switch
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Figure 9. Tripod Mount
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Hardware
4.4 Illumination Board
The illumination board consists of 4 IR lasers mounted with diffusers and the laser driver ckt. The optical output power of the illumination board is controlled using an I2C interface-based digital potentiometer. The voxel viewer software can be used to configure the digital potentiometer. The modulation control of the illumination is done by the OPT8241 sensor and the corresponding signals from the sensor board to the Illumination board via a flex cable.
Table 4 lists the specifications of the illumination boards.
Average Output Power(^) 1.5 W
Peak optical output power 10 W
Modulation frequency 12-MHz to 80-MHz square wave at 50% duty cycle
Laser Beam Divergence 80° at 90% power relative to the center
Transverse Beam Mode Diffused
(1)
All values are typical.
Table 4. Illumination Board Specifications
Item Specification
Size 60 mm (W) x 48.5 mm (L) x 12.1 mm (H)
Illumination type 4 x Near IR Laser
Pulse train width 18 µs–28 ms
Wavelength 850 nm
Laser Beam Shape Circular
Diffuser Material EDC-80, RPC photonics
(1)
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The illumination power can be changed only between 40% to 100% of the total power. Values below 40% of the maximum power are not supported. Since each board's maximum power is individually tuned to make sure that the 100% power setting meets the laser safety requirements, the valid steps between 40% to 100% power can differ across CDKs.
4.5 Power Supply
The image of the power supply recommended for use with the CDK along with all the blade options is shown in Figure 10.
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Hardware
Figure 10. Power Supply
The power supply specifications are shown in Table 5.
Table 5. Power Supply Specifications
Item Specification
Part Number EMSA050300-P5RP-SZ Output Voltage 5 V Output Current Up to 3 A
Input Voltage 90 ≈ 264 VAC
Frequency 47 to 63 Hz
Efficiency Level V
Blade options US, UK, Europe, Australia, China
(1)
All values are typical.
NOTE: TI recommends using an external power supply that complies with applicable regional safety
standards such as (by example) UL, CSA, VDE, CCC, PSE, and so forth.
(1)
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Calibration
5 Calibration
The CDK is factory-calibrated. The calibration on the CDK is for demonstration purposes only and is not meant to be treated as the most accurate calibration possible. Since the CDK can be configured dynamically using the software, the CDK goes out of calibration whenever a critical parameter is changed. Three default profiles are provided in the hardware to serve as templates. Table 6 lists the default calibration profiles.
(1)
Since Long range profile derives from lens calibration profile, lens calibration is not redone in long range profile.
(2)
Profiles that have a parent derive all the calibrations from the parent. Calibrations in a child override the calibrations derived from the parent.
Table 6. Calibration Profiles
Parameter Long Range Short Range High Ambient
Parent Profile Lens Only Long Range Long Range
Frame rate (fps) 30 60 30
Sub-Frames 4 2 4
Quads 6 6 6
Integration Duty Cycle (%) 30 10 5
De-aliasing Enabled Enabled Enabled
Illumination Power (%) 100 40 100
Unambiguous Range (m) 10 5 5
Base Frequency (MHz) 60 60 60
De-aliasing Frequency (MHz) 40 40 40
Usable Range 4 m 1.5 m 1.5 m
Calibrations performed
Temperature, Common
phase offset, Pixel to
Pixel, Pixel cross-talk
Common phase offset
(1)
(2)
Common phase offset
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(2)
Calibration is very sensitive to system parameter changes. Any change in a parameter value could put the CDK in a non-calibrated state. The most common parameter changes that mandate re-calibration are listed in Table 7.
Table 7. Calibration Sensitivity Table
Re-Calibration Required?
Parameter Changed
Unambiguous range (any change in
modulation frequency)
Frame rate, number of quads,
number of sub-frames (any change
in quad timing)
Integration duty cycle Yes, but to a small extent No No
Illumination power Yes No No
Common phase offset
Yes Yes Yes
Yes, but to a small extent No No
Pixel-to-Pixel Differences
Non-Linearity Calibration, Pixel Cross-Talk Calibration
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6 Software
The CDK is supported by the open source 3D Camera software development kit – Voxel-SDK. To make the evaluation easier, Voxel Viewer, a closed source viewer built on top of Voxel SDK is provided by TI. The viewer supports the following functionality:
• View the following streamed data real-time: – Phase – Amplitude – Ambient – Distance – Depth – Point cloud
• Configure the camera settings
• Basic statistics: – Temporal and spatial averaging – Temporal and spatial standard deviation – Histogram
• Filters (Spatial and temporal): – Filter addition/deletion/insertion – Configuration of filter coefficients
• Calibrate the camera
• OPT9221 firmware update
The details of the viewer are covered in the Voxel Viewer User's Guide.
Software
6.1 Firmware upgrade
The CDK has two firmware. The FX2 firmware and the TFC (OPT9221) firmware. Both the firmware are stored in separate EEPROMs. Firmware upgrade is a critical activity and the following precautions must be adhered to:
• The CDK should be adequately powered using the recommended power adapter.
• Only the recommended software should be used for firmware upgrade.
• Loading firmware other than the firmware provided by TI is not recommended and could lead to hardware failure.
6.1.1 FX2 Firmware upgrade
FX2 firmware upgrade is accomplished using the Cypress Control Center tool. The procedure follows:
• Launch the cypress control center tool. If the CDK is connected, the CDK is listed in the control center tool.
• Choose "TI 3DTOF CDK OPT8241" among the devices listed.
• Click on the menu option – Program → FX2 → 64KB EEPROM.
• Choose the provided firmware file and click on open to start the programming.
• If the programming goes through, the status bar shows "Programming Succeeded".
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OPT8241 Evaluation Module
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Software
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OPT8241 Evaluation Module
Figure 11. Cypress Control Center
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Software
6.1.2 TFC (OPT9221) Firmware Upgrade
The OPT9221 firmware can be updated using the Voxel-Viewer tool. The procedure follows:
• If the Voxel Viewer application is already running and connected to the CDK, launch the "Voxel Programmer" utility from the menu – File → Open Programmer
• If the Voxel Viewer application is not running, the "Voxel Programmer" utility can be directly launched from the start menu in Microsoft®Windows®or from a terminal in Linux®.
• Once the programmer is open and is connected to the CDK, choose the provided OPT9221 firmware file and click on the download button.
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Figure 12. Program Menu
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Software
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Figure 13. Launching the Programmer From the Voxel Viewer
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OPT8241 Evaluation Module
Figure 14. OPT9221 Firmware Download
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7 Known Issues
List of known issues for the hardware revision Rev2P0:
• Hardware issues: – When the USB cable is connected, the red LED on the illumination board turns on even when the
power switch is in the off position. This is behavior is not harmful and the rest of the circuit is indeed powered off. Occasional blinking may also be observed.
– The lens mount has no alignment tabs. This results into incorrect centering and hence noticeable
vignetting near the corners of the image. – Hot unplug of power supply DC jack may lead to power failure and board reset. – The OPT8241 LVDS data capture on the TFC has latency issues and will be fixed in a future
OPT9221 firmware. As of firmware version 0.23, the latency issue is not resolved. The issue
manifests itself as a 1-in-8 column pattern both in phase and amplitude images and disappears
when "data_latency" parameter is adjusted by ±1.
• Calibration issues: – Frequency calibration is not performed on the boards. This may lead to gain errors in distance
measurement.
– Non-linearity calibration is not performed on the boards. This may lead to varying phase slopes
versus distance.
8 Related Documentation From Texas Instruments
Related documentation regarding the EVM is available here: http://www.ti.com/tool/opt8241-cdk-evm. The documentation related to the ToF chipset used in the EVM is available in the following:
• Sensor - http://www.ti.com/product/OPT8241
• Time-of-Flight Controller - http://www.ti.com/product/OPT9221
Known Issues
Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from A Revision (February 2016) to B Revision ............................................................................................. Page
• Added class A product statement pertaining to EN 61326-1:2013 in the Safety section. ....................................... 5
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Revision History
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