cancel
Showing results for 
Search instead for 
Did you mean: 

VL53L4CX one-cycle delay in the returned data

sctz
Associate III

Hi:

When I move the object detected by the VL53L4CX, I find that there is a one cycle delay in the distance it returns. Is this because its first data is discarded?(Range status=6)? Is there a way to improve this?

Thankyou.

Cyt

 

1 ACCEPTED SOLUTION

Accepted Solutions
John E KVAM
ST Employee

This is really interesting. I never figured out how to move a target and determine if there were any latency or not. It would be interesting if you can share your experiment procedure.

In order to detect something called 'radar aliasing' the sensor alternates between ranges with different pulse repetition intervals. So you get an A range and a B range. For the very first range, you get a status 6 - meaning the aliasing was not checked. With the B range, you get verification, and then get normal a status.

When your target moves, the A range will not correlate with the B range and you might get a status indicateing you might have a aliasing issue (also called wrap-around.)

I'm going to guess that you are tossing out the status 4 or 6, thinking it's an error. But if you have reason to believe the status was due to motion and not aliasing, you can accept the status simply as a warning. Both ranges were correct when you took them. 

 


If this or any post solves your issue, please mark them as 'Accept as Solution' It really helps. And if you notice anything wrong do not hesitate to 'Report Inappropriate Content'. Someone will review it.

View solution in original post

2 REPLIES 2
John E KVAM
ST Employee

This is really interesting. I never figured out how to move a target and determine if there were any latency or not. It would be interesting if you can share your experiment procedure.

In order to detect something called 'radar aliasing' the sensor alternates between ranges with different pulse repetition intervals. So you get an A range and a B range. For the very first range, you get a status 6 - meaning the aliasing was not checked. With the B range, you get verification, and then get normal a status.

When your target moves, the A range will not correlate with the B range and you might get a status indicateing you might have a aliasing issue (also called wrap-around.)

I'm going to guess that you are tossing out the status 4 or 6, thinking it's an error. But if you have reason to believe the status was due to motion and not aliasing, you can accept the status simply as a warning. Both ranges were correct when you took them. 

 


If this or any post solves your issue, please mark them as 'Accept as Solution' It really helps. And if you notice anything wrong do not hesitate to 'Report Inappropriate Content'. Someone will review it.

HI

The test works like this:

I use a O/E Converter to get the signal of the L4's light. When I put an object between the chip and the O/E Converter, O/E Converter  will not receive the signal . I use this to determine the delay between the output of the chip and the change in the actual object.

Regarding the slow response, I have confirmed that it may be that the data calculation is taking too much time in MCU processing causing me to mistakenly think that it is slowing down by one cycle... Thank you very much for your explanation.

Cyt