Question for VL53L0X Accuracy Mode and Possibility store application specific factor on sensor

[YGude.1]

e are operating VL53L0X in High Accuracy mode with time budget configured to 9000msec.

Please help us to understand how sensor taking multiple sample and gave final stable output in high accuracy mode.

We are going to use this sensor for distance measurement of piston inside syringe. For same plan is to put sensor on cap of the syringe. During initial testing with multiple sensor board, when piston is at top of syringe, we observed variation in reading. That indicate, we might need to store application specific factor with sensor. For same we might need to make provision of eeprom with Vl53L0x sensor on sensor board. 

We wanted to know, is there any possibility to store such "Application specific factor" on VL53L0X sensor, so we can avoid eeprom?

If answer is No, then is there any alternative part available (similar in size of VL53L0X ) where we can store "Application specific factor"?

[John E KVAM]

Ouch. No it's not the syringe that bothers me, it's the fact that none of our Time of Flight sensors have any EEPROM inside where you can store some calibration data.

ST does sell EEPROMs that are only a few cents. (You are not the first to ask, so I looked it up.)

Another issue is the VL53L0X has a issue at the very close distances. You will see that below about 1 inch, the distance measurement starts to go UP when you expect it to go DOWN. For this reason we always recommend that custoemers set the sensor back an inch into their housing if they can. That avoids the issue.

(I'm guessing here that you are interested in the very short distances.)

We are working very diligently on this close distance issue, and expect to have a part out in September that does a much better job both with accuracy and with the very short distances. It has the same foot-print and physical shape, and the software API is nearly identical. So by all means continue your development and stay tuned for our announcement in the Fall.

[YGude.1]

​Thanks John for your reply.

As you mentioned, we are placing sensor few inch back into housing .

I also asked about sensor working in high accuracy mode to take multiple sample and gave final stable output.

Please provide some insights.

We are using Vl53L0x for distance measurement up to 20 cm. While testing with filter glass (recommended by ST)  we observed result deteriorate by 1mm for few measurement areas.  Now I will work cross talk calibration, some software filter in order to overcome 1 mm  deterioration of result.

From ST side, if you provide some input on this deterioration and possible solution to overcome same then it will helpful to us.

[John E KVAM]

Putting the sensor into high accuracy mode just means that we ping more often. The closer together we put the pings, the less distance we can range, so it's a tradeoff.

But if you are ranging to less than 1M it will work just dandy.

Read the datasheet on accuracy. It shows better numbers if you double the timing budget from 33ms to 66ms. As a general rule you will get a 2X improvement in accuracy with a 4x increase in timing budget.

Because you know what you are looking at, you will be able to do better than our spec, and using a longer timing budget will help as well.

Unfortunately you are NOT going to get mm accruacy. That's the holy grail of this type of sensor and we are gettting closer with our 'next' part. But I cannot promise anything yet.