SensorsのトピックRe: MMA8652, problem with freefall/motion flag reading. Desperately need help!

MMA8652, problem with freefall/motion flag reading. Desperately need help!

samkuliev — Tue, 03 Feb 2026 22:36:12 GMT

Hello,
I am using MMA8652FC accelerometer in on of my developments and desperately need help to solve the following problem as I am way behind schedule because of this.

Regardless of the setting of "OAE" and "ELE" in FF_MT_CFG Reg:0x15 and values in 0x017 and 0x018, bit "EA" in FF_MT_SRC 0x016 is getting locked with "Z" axis up. Entire register is acting more like Portrait/Landscape at 0x10.

My intentions are simply to read the motion bit in 0x16 and activate, or deactivate the light.
What am I doing wrong?

Re: MMA8652, problem with freefall/motion flag reading. Desperately need help!

TomasVaverka — Tue, 22 Nov 2016 08:43:48 GMT

Hello Sam,

Please try using the embedded transient detection function that triggers an interrupt when any of the enabled axes has exceeded a set acceleration threshold disregarding the static acceleration. So the data that is compared to the threshold to be exceeded is high-pass filtered data. For more info, please refer to the AN4071.

Best regards,

Tomas