8452 vehicle motion

[marcick]

Hi all,

which is the best interrupt option/configuration using this sensor to quickly detect a vehicle (car) movement, without be sensitive to other vibrations (doors opening for example) ?

I need to detect when the vehicle really start moving to generate an alarm.

[marcick]

Hello, I'm actually using this configuration to detect vehicle movement. Is there anything I can do to increase sensivity ?

I'm trying to play with register without success

$2A, [$18] ' 0x2A: CTRL_REG1 system control 1 register, Set device in 100Hz ODR, Standby
$1D, [$1E] ' 0x1D: Transient_CFG register, enable latch, Enable XYZ
$1F, [$01] ' 0x1F: TRANSIENT_THS register, set threshold to 1 counts
$20, [$05] ' 0x20: TRANSIENT_COUNT, set debounce 50mS
$2D, [$20] ' 0x2D: CTRL_REG4 register, enable transient interrupt
$2E, [$20] ' 0x2E: CTRL_REG5 interrupt configuration register, Route the Transient Interrupt to INT 1 hardware pin

[reyes]

Hi,

I recommend you to use the Transient Detection embedded function because it compares whether any of the enabled axes has exceeded a set change in acceleration disregarding the static acceleration. The data that is compared to the threshold to be exceeded is high-pass filtered data.

The application note AN4071 can help you to understand what is this embedded transient detection function and how to properly set the registers to use this function.

And you can also use the application note AN4601 as a more specific guideline for your application since for this document, the MMA8452 was used to detect whether a car is moving by combining the accelerometer's auto-wake/sleep and transient detection functions.

Have a great day,
Jose

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[marcick]

Great.

Thank you very much for the excellent support.

Marco