OPT3101EVM: OPT3101EVM

Kailyn,

Take a look at https://www.ti.com/lit/pdf/sbaa303 -  Extending the Range of OPT3101 Systems. This app note will provide more information on longer range measurements.

Using the standard EVM to increase the range will not provide the maximum range the customer may be looking for. The beam angle and sensitivity of the IR LED's play a large factor in range. Some customers use LiDAR to get longer distances. To see how this functions look at:

EVALUATION BOARD
BW-3P-TF02-PRO — Benewake TF02 Pro LiDAR module (long-range distance sensor)
The TF02 PRO module is based on the OPT3101 and is a single-point long-range LiDAR sensor. The sensor is low cost, small size and low power consumption with excellent performance produced by Benewake.
From: Benewake

Let me know if you have any further questions. 

Kailyn,

  You need to do the calibration with the HDR mode turned off. In order to go back to operating mode with longer range you need to turn HDR back on.

Pengsheng,

 Take a look at the OPT3101Coefficients.cpp file of the SDK. To be honest the automated method using an MSP430 board and the SDK code is the best method of doing the calibration. Read the code, it will walk you through the entire process. It's possible you are missing something in calibration that the automated version in the SDK will resolve. 

The problems you are seeing are not common with other customers. I recommend that you read through the process in the cpp file. Attempt to recalibrate based on using this method then if it does not work, let me know and please include a very detailed description of your test setup and procedure. I will review it and get back to you. 

Pengsheng,

  I am sorry about the delay, it took soime time to find and understand what you were seeing and replacate your problem, them find a solution. This is what we believe is your problem and solution.

In HDR mode, the current can switch between 2 current settings on one TX channel, and with super-HDR, TX1 can be used to add 2 more current settings.

What we think is going on here is that the phase offset measurements are not being done at the proper amplitude for each current setting.

The documentation recommends doing phase offset calibration at a target distance where the amplitude is between 16000-24000. The preset values in the SDK are arbitrary and definitely don’t follow this rule. The values are set like below in OPT3101Coefficients.cpp.

void environmentalController::manuallySetReferenceDistances(){

       this->refDistancesInMM[0][0]=50;

       this->refDistancesInMM[0][1]=120;

       this->refDistancesInMM[1][0]=60;

       this->refDistancesInMM[1][1]=150;

       this->refDistancesInMM[2][0]=0;

       this->refDistancesInMM[2][1]=0;

} 

The indexing on refDistancesInMM is [Tx channel] and [current setting, 0 being H and 1 being L]. In order for them to find the proper distances to set for each current and tx setting, you will need to change your configuration to do just one current, flash that, and see at what distance you can get 16000-24000 codes for that particular current. At higher currents, that distance will be pretty far with a white background, so you can use darker backgrounds in order to get lower amplitude settings, but they’ll need to remember what current settings used what color background when you do the calibration.

 Once you know these distances, you can enter that into OPT3101Coefficients.cpp and then use super-HDR configuration and perform the calibration.

This method is used to get extended range because it moves the IQ data calculations into the other quadrants. For more information look up IQ demodulation techniques. 

It's important to tknow that this part is not Direct TOF but Indirect TOF and calculates distance based on the phase angle not a single pulse time. This is why this part is so much better and accurate.

Let me know how this works. 

Pengsheng,

  I use a heavey weight card stock 90+ bright white, 300mmx300 and a flat black low pile carpet, 300mmx300mm. I set the height of the OPT3101EVM to emimit and receive in the middle of the reflectors. The distance is determined by the amplitude of the reflective signal.

No it is not required to use Lambertian surfaces. It is somewhat expected that the reflective angle will be 180 degrees. 

Pengsheng,

  In the OPT3101Coefficients.cpp file in the SDK is the location that you will insert the results from each step of the calibration sequence. No the data is not saved automatically. You will need to capture it in the UART window where the feedback is presented, then inserted into the the calibration file. This will need to be done for each step of the calibration.

The purpose of the Light is to represent strong ambient light or sunshine. You need about 100k LUX of light. The EVM has a photodiode with IR pass filter and an LED has a narrower bandwidth than sunlight. You should use halogen because an LED won’t have any IR.We recommend halogen lamp due to matching close to sunlight.

The only time humidity will impact light measurments is 90+ percent humidity (97-100 is fog, rain or under water) We recomment less that 80 percent humidity for the calibration.

Hopefully you are making good progress on the calibration. Based on your questions and other customers as well, I am rewriting the calibration document. It will be after the new year, but your questions and comments are helpful. 

Pengsheng,

For step 4 ambient cal Look at 3.6.3 Phase offset Ambient coefficient in the how to calibrate doc. It does not mean to mask the photodiode. You need to sweep ambient light from 0 to max (see Figure 7. Phase offset vs Ambient data)

The SDK only erases when the writeToFlash/EEPROM command is called. I believe SDK is by default storing in local file on the PC assuming they are running SDK on windows PC. And then load calibration functions called it writes the file values into 3101. There is a flash in the calibration functions if you want to saveToFile or use EEPROM.

Pengsheng,

SDK does not write/load the system level coefficients to EEPROM because these values should not change across devices so won't need to change values in OPT3101Coefficients.cpp when loading firmware to a different unit.

The EEPROM is read by the OPT3101 on device reset and the device loads the EEPROM values into the registers. More detail in page 32 of the datasheet.

I will end and lock this thread. Please feel free to start a new question at any time. We like the E2E questions to be individual questions to make it easier for others the track and find solutions. When the question continues but also goes in a different direction it needs to be closed and locked. 

Thank you.