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harald
harald
Associate III
November 7, 2016
Question

Half sensitivity of one VL53L0X

  • November 7, 2016
  • 1 reply
  • 490 views
Posted on November 07, 2016 at 11:56

Hy,

for a proof of concept I created five identical devices, each having 3 VL53L0X, so I have an overall of 15 VL53L0X that are mounted (behind an acrylic glass shade) and connected (via 2.8V, I2C) identically. During test of my devices I observe, that one of the sensors has quite exact the half sensitivity of all other devices: amplitude is about half, standard deviation is about four times of the other sensors.

I can't see any optical explanation for this: no scratches nor soiling of the front glass. Might there be any other explanation? Do I need to characterize devives before I use them?

Regards

Harald

#vl53l0x #sensitivity
This topic has been closed for replies.

1 reply

Julien NGUYEN
Julien NGUYEN
ST Employee
February 21, 2017
Posted on February 21, 2017 at 03:54

Hi Harald,

When you add the cover glass on the ToF sensor, you need to perform the crostalk calibration before. The crostalk value can be stored in the host and to be loaded during the system power ON.

You may check if the plastic film protection on the top of sensor which has the problem, had been removed

Please find the link to download the cover glass guide

https://my.st.com/content/ccc/resource/technical/document/application_note/group0/9d/93/be/33/13/be/46/19/DM00326504/files/DM00326504.pdf/jcr:content/translations/en.DM00326504.pdf

 

Thanks,

Julien

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harald
haraldAuthor
Associate III
February 24, 2017
Posted on February 24, 2017 at 00:20

Hy Julien,

thanks for your response (only 3.5 months after my question).

As I describe in my report, I have15 sensors in the identical situation, each has same cover glass, each performs crosstalk calibration on every device startup (no need to store calibration values to eeprom, there is no hurry on startup).

And only one of the 15 devices behaves differently. So I can rule out all external reasons, the device itself seems different.

Have you ever heard of a 'half sensitivity'?

Regards

Harald

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