STHS34PF80 – Data remains constant, TOBJECT = -48

[los_trpaslikos]

Hello,
I am trying to get the STHS34PF80 sensor working on an STM32L0 platform via I²C. My initialization sequence is as follows:

1. Algorithm reset according to AN5867:

CTRL2 (0x21) = 0x10  // FUNC_CFG_ACCESS = 1
PAGE_RW (0x11) = 0x40 // FUNC_CFG_WRITE = 1
FUNC_CFG_ADDR (0x08) = 0x2A
FUNC_CFG_DATA (0x09) = 0x01
PAGE_RW (0x11) = 0x00
CTRL2 (0x21) = 0x00

1. Interrupt configuration:
   CTRL3 (0x22) = 0x05

2. AVG_TRIM:
   0x10 = 0x01

3. Continuous mode:
   CTRL1 (0x20) = 0x15 (BDU=1, ODR=4 Hz according to datasheet)

After this, I wait for EXTI interrupt (DRDY). On interrupt, I read:

• STATUS (0x23)
• TOBJECT_L/H (0x26/0x27) and etc.
• FUNC_STATUS (0x25)

Problem:

• The TOBJECT value remains constant (-48), even when I place a hand or heat source in front of the sensor.
• Presence/motion flags in FUNC_STATUS almost never change. Occasionally, I see a value of 1, but very rarely, even when moving a hand or breathing near the sensor.
• See attached screenshot of current data from the terminal.

Questions:

• Is my initialization sequence correct?
• What could cause TOBJECT to stay constant?
• Are there recommended threshold and AVG settings for reliable detection?

Thanks for any tips or reference to a working example.

[casadeib]

Hi @los_trpaslikos ,

Are you using STM32L0 platform together with a custom PCB with STHS34PF80? Can you please give us more details on you HW setup? Did you find out this issue only on one part?