LPS28DFW FIFO update lock

[SimoCali]

Hello,

I have a couple of devices using LPS28DFW pressure sensors.

The sensors are configured as follows:

• INTERRUPT_CFG = 0x00,
• THS_P_L = 0x00,
• THS_P_H = 0x00,
• IF_CTRL = 0x00,
• CTRL_REG1 = 0x3C,
• CTRL_REG2 = 0x00,
• CTRL_REG3 = 0x01,
• CTRL_REG4 = 0x02,
• FIFO_CTRL = 0x02,
• FIFO_WTM = 0x64,

All other registers are left at their default values.

Usually they work fine, filling the FIFO with new data and generating an interrupt every second. However, I occasionally encounter an issue where the sensors appear to stop filling the FIFO for a period of time. The duration of this stall is not consistent, it can range from a few seconds to a permanent lock-up. During this locked state, I can still successfully read the temperature, and reading back the configuration registers confirms they are set as expected. After a power cycle and reconfiguration, everything returns to working correctly.

Have you ever experienced this issue? Do you have any idea what might be causing it?

[Federica Bossi]

Hi ​@SimoCali ,

I would first check FIFO_STATUS1 / FIFO_STATUS2 / STATUS / INT_SOURCE when the stall happens. If FIFO_FULL_IA, FIFO_OVR_IA, or P_OR is set, it’s likely a FIFO overrun/state issue rather than a sensor failure.

A simple recovery to try is to put the FIFO in bypass (FIFO_CTRL = 0x00), wait a bit, then reconfigure it.