noise reduction for VL6180X

[Ioannis Manousakas]

Hi,

I am using a VL6180X sensor with

SYSRANGE__MAX_CONVERGENCE_TIME: 63

READOUT__AVERAGING_SAMPLE_PERIOD: 255

What are the best settings for minimal noise?

Are there any other setting I have to adjust?

I also have seen the video https://www.youtube.com/watch?v=7INefyjvvdI talking about using a cover glass. Is there any information on how to design such a cover glass?

Thanks for your help.

[John E KVAM]

There are very few 'adjustments'. With your max convergence time set to max, the sensor will gather photons until it has enough and then will return an answer.

Do read the section on SNR. It will 'warn' you about marginal measurements.

​That is a great video and explains the problems and gives one solution. But you may not have to go that far. That video assumes you are building something like a robotic vacuum cleaner where getting dirty is a given. But for almost anything else a bit of clear glass or plastic is all you need. The best cover 'glass' is acrylic or PMMA or actual glass. Best if it is smooth on both sides, clear to 940nm light, thin and close to the sensor. Or if you would like there is a  company that makes them. Hynix is in Taiwan, but they have a distributor in western Canada.

AB Embedded Systems Ltd. (Canada)

info@abmbed.com

1. Pricing

https://www.dropbox.com/s/5iy8qr3zamjk0ru/2018%20Hornix%20Price%20List%

2. Ordering via email via info@abmbed.com

Hynix makes quite a few types of cover glass, and even has one part with the sensor, the glass, a calibration eeprom and a connector. You just need to provide the wring to your MCU.

But do read the user manual on calibration. For the best measurements - it's invaluable.

[Ioannis Manousakas]

Thank you for the reply. I will try a more "aggressive filtering".

I need the glass because the sensor will be in a pressure changing environment (0 to -55kPa) and may be high humidity. I was thinking something with opaque barrier in the middle. The company you mentioned is Hornix Optical Technology Inc from Taiwan (http://www.hornix.com.tw/en/product-list-3/). The thickness is about 0.85mm and I do not think it can withstand repetitive pressure changes...So DIY glass cover may be my solution.

[Ioannis Manousakas]

The video also mentions that the cover glass 3D model is availiable at ST.

How could I get it?

[John E KVAM]

Here you go. Original e-mail below mentioned the VL6180, but if I got the wrong part, please ping me. But the file should have been on the web site somewhere. - john [sensor2]VL53L1X – Time of Flight Sensor John KVAM | Tel: (408) 919-8502 | Mobile: (650) 521-2084 STMicroelectronics | 2755 Great America Way, 3rd Floor | Santa Clara, CA 95054 Introduction to Time-of-Flight<> and SensorExpo Time-of-Flight<>

[algis]

Can you please update the information where is it possible to get the cad model?

[John E KVAM]

The easy way to do the coverglass is to buy it from Hornix in Tiawan. They are an optical company that specializes in molding plastics.

Otherwise all you need out of that coverglass design is some way to hold the 2 pieces of glass in and keep them optically separated.

You question about the noise is harder.

Would it be possible for you to average several ranges?

Looks like you have done what you can.

There is one other bit of advice. The VL6180V1 is the exact same silicon except we filled in the ALS hole and don't calibrate the ALS.

This version of the chip has identical silicon, but it's easier to get and a few cents cheaper.

• john

[Ioannis Manousakas]

It is the same as two years ago...

In my case...I learned FreeCAD and design it myself. I share it here in case it can be useful to anyone...

I 3D printed using a company I found on the internet.

I then cut glass from microscope plates and fitted using epoxy glue.

The results were presented here: https://doi.org/10.1371/journal.pone.0242371