Ranging and Timestamp for a dynamic ToF + IMU sensor

[RyanPike]

I have the timing budget set to 56ms. Have histogram merge turned off, and histogram max size set to 1.

I also have an IMU on board. I have also enabled Phase cal patch power. The following is the setup.

I am having trouble getting returns above 1.2metres, and is there any way of estimating the timestamp with higher fidelity. At the moment I am just taking the mid-point from when it starts ranging to when we can load the sensor. Its not using a GPIO pin, its using the blocking getMeasurementData function, we have instrumented that poll and have included that into the timing measurement.

 

Just want to know if theres any tricks we can do to get it comfortable returning 2+ metres, there are 16 sensors pointing radially outward. The sensor has slow  and fast dynamic motion that it undergoes.

[RyanPike]

Also is it at all possible to get basically an azimuth / elevation inside the ToF FOV?

[RyanPike]

Also this is an L4CX ToF model.

[Bin]

Hi,

Please see the main points below:

1. Range above 1.2 m / target 2 m+
According to the Datasheet - VL53L4CX - Time-of-Flight sensor with extended range measurement, for a 17% gray target under reference conditions, VL53L4CX can typically reach around “2.1 m at 90% detection rate”.  
So, 2 m is possible, but it depends strongly on:
- target reflectance and size
- whether the target covers enough FoV
- ambient IR
- cover glass / crosstalk
- timing budget
- motion
- multi-sensor interaction

Recommended checks:
- use “Medium distance mode” for maximum range
- try increasing timing budget beyond “56 ms” if frame rate allows
- make sure “RefSPAD / Xtalk / Offset” calibration is correctly done in final assembly conditions
- if multiple sensors run together, check possible interaction by comparing “1 sensor vs multiple sensors”
- First, we recommend checking the sensor in a simple reference setup: keep both the sensor and target still, test indoors with minimal IR, and use a large flat target that fills most of the FoV. This helps establish the baseline ranging capability before evaluating the full dynamic multi-sensor system.

 

2. Timestamp accuracy
Per A guide to using the VL53L4CX Time-of-Flight sensor with extended distance measurement - User manual, the `TimeStamp` field is not implemented, so there is no precise internal timestamp available from the API.  
Your midpoint estimation is acceptable as an approximation, but for better timing fidelity, using “GPIO1 interrupt”, timestamping on interrupt arrival, then reading the data immediately.

 

3. Azimuth / elevation inside FoV
A single VL53L4CX cannot provide azimuth/elevation inside its FoV. It is a single-zone ToF sensor, not a multizone angular sensor.  
With your 16 radially arranged sensors, you may estimate coarse direction at system level by combining outputs from multiple sensors, but this is not something one VL53L4CX can output directly.

Best Regards,

Bin FAN