Skip to main content
C
chadrockey
Visitor II
October 17, 2023
Question

Difference Between A and B Message

  • October 17, 2023
  • 1 reply
  • 874 views

I've seen references to various A and B or (even and odd) messages for the ToF sensors.

In my application, it turns out that every other measurement is not great, so if I throw out packets based on their message ID count, then I get perfect data but at half measurement rates.  The effect I see is that the measurements oscillate between the real value and a nearby (within 6 or 10cm) value.

I think for my sensor, the packet that contains the ambient data is the better one.

Is there more documentation on what the two packets are and why the measurements would be different between the two?  Is there a way to set them both to operate the same so that I don't lose half the samples?

This topic has been closed for replies.

1 reply

Anne BIGOT
Anne BIGOT
Technical Moderator
October 20, 2023

Hello

There are two different VCSEL periods that are used alternatively. This is used to avoid wraparound at long distance. 
Do you need to drop half of the values at long or short distances ? What is the sensor you are using ? For some, there is an offset calibration option allowing to compensate this effect. For the VL53L3CX, it is for example : PerformOffsetPerVCSELCalibration.

Regards

Anne

Our community relies on fruitful exchanges and good quality content. You can thank and reward helpful and positive contributions by marking them as 'Accept as Solution'. When marking a solution, make sure it answers your original question or issue that you raised. ST Employees that act as moderators have the right to accept the solution, judging by their expertise. This helps other community members identify useful discussions and refrain from raising the same question. If you notice any false behavior or abuse of the action, do not hesitate to 'Report Inappropriate Content'
Terms & ConditionsAccessibility statement