STHS34PF80 Presence Detection Issue: Short Detection Range and Stuck Presence Flag

[mobaid]

Hello ST Community,

I'm currently working with the STHS34PF80 sensor for presence detection on an STM32WB55 development board. However, I've encountered a couple of issues that I hope someone here can help with:

1. Short Detection Range: The detection range without any lens is quite limited, averaging around 1 meter. This is significantly shorter than what I expected for my application. I’m wondering if others have experienced similar range limitations and if there are any suggestions or adjustments that can improve this.

2. Stuck Presence Flag in Register: After a presence is detected, the presence register value maintains a fixed high value even after the object has left the sensor’s detection zone. This causes the presence flag in the function status register to remain raised and not get cleared automatically. As a result, I am unable to reliably use the presence detection for further processing because the presence flag doesn’t reset as expected.

Has anyone encountered similar issues with the STHS34PF80? If so, how did you resolve them? Are there any specific configurations or workarounds to ensure that the presence flag resets correctly after an object leaves the detection zone?

Any insights or suggestions would be greatly appreciated.

Thank you in advance!

Best regards,
Mohamed Obaid

[ola]

Hi ST,

Can someone from ST please help with poor detection range on the STHS34PF80 sensor as I am having the same problem where detection is only about 1 meter as described in the above post.

Regards

Ola

[mobaid]

Second issue is solved "Stuck Presence Flag in Register" here

https://community.st.com/t5/mems-sensors/sths34pf80-sensor-detects-false-presence-after-inanimate-object/m-p/714147/highlight/true#M24084

but the range is still short average 1meter even with less presence threshold 50~100 LSB
and the FOV seems to be less than 80' without a lens

[mobaid]

You may reduce the presence threshold e.x.

sths34pf80_presence_threshold_set(&dev_ctx, 100);

if it didn't work , it's my issue here .

[ola]

Hi Mobaid,

Thank you for the link to the solution to the first issue about "Stuck Presence Flag in Registers" I am now setting the SEL_ABS bit in the  ALGO_CONFIG register as part of my initialization and I just have to keep an eye out to see if there are any improvement in behaviour. 

I make the above comment because for many days after my initial implementation of the driver I never saw the issue with the PRES_FLAG until two days ago when I was doing a demo and then I noticed that the PRES_FLAG intermittently would not clear when an object is out of the FOV. 

For my implementation I am using interrupt. I have the MOT_FLAG routed to the interrupt pin and when it triggers I read the FUNC_STATUS (0x25) register for the PRES_FLAG bit.

I will try and remember to report back if I no longer see the issue with presence flag.

Regards

Ola

[mobaid]

Hi Ola ,

Sounds great! Looking forward to hearing if the presence flag issue is resolved. Let me know how it goes!

best regard ,
Mohamed Obaid