Ambient light level with vl53l8cx ?

[kgb]

Hello Everyone !

I would like to know if it is possible to measure ambient light levels  either directly or indirectly , using the VL53L8CX sensor.

Thank you in advance

[John E KVAM]

The short answer is no.

There is a filter over the receive section of the sensor that blocks out all the light except the 940nm produced by the VCSEL (laser). So ideally all we see is the light we sent out. But the sun also generates 940nm light. And this 940nm light from the sun is what we call ambient in the VL53L8 manuals.

One could I suppose get a measure of the ambient 940nm light from the sun and guess at how bright the day is. But indoor lights generate almost no 940nm now that halogen lights are a thing of the past.

At one time ST made a part (VL6180) that had an ALS embedded in it. But after a grand run of 10 years we replaced it with a better ToF sensor, and there wasn't the demand to keep the ALS. 

If you need an ALS and you want it small, consider the VD6283 from ST. It's really quite good and amazingly tiny. 

Have a look.

- john

[kgb]

Hallo @John E KVAM,

following your recommendation, I ordered an evaluation board for the VL6180X ambient light sensor. However, I'm now realizing that the sensor may be obsolete ? Can you please provide me more details about its status?

[John E KVAM]

The VL6180 line is obsolete. I'm sorry if that was not clear. The VL53L4CD is the replacement, but it does NOT have an ambient light sensor (ALS). ST does make an ALS - the VD6283, and it's pretty good. But its key feature is that it can detect flicker from LED and other artificial lighting. It's also the smallest ALS on the market. So, if you need Flicker detect and small it's the best on out there. But others clearly make one as well.

If you bought the 6180 EVK I'm sorry, but it's not all bad. if you buy the X-Nucleo-53L4A1, you can use it with the white STM32F401RE board from the 6180 EVK. Save you $10 or so. (The P-Nucleo-53L4A1 consists of the X-Nucleo-53L4A1 AND the STM32F401RE board.)

- john

 

[kgb]

Hello @Anne BIGOT ,

Thank you for your reply. We are currently considering using the VL53L8CX in combination with the VD6283TX for a specific application, instead of the VL53L4CD. However, we’re concerned about potential interference between the two sensors when placed in close proximity. Could you or someone else clarify whether any disturbance might occur in this configuration?

Thanks

[John E KVAM]

the VL53L8CX operates at 940nm and that is in the low infrared area. It's clearly in the IR band of the VD6283TX. 

As it doesn't interfere with the RGB or Visible, you can still use those. 

But the ALS chip is fast. You could run the L8 in Autonomous mode and leave a small gap between measurements. In those gaps you could run the ALS and do what you need to do. 

Or - as the VL53L8 has a sync pin - you could stall the L8, take your ALS measurement and then trigger the L8. 

- john