How to detect crash using BMI 323?

[gunbu99]

hello

I'm trying to detect crash using bmi 323.

I used anymotion feature but it doesn't work as I thought

I think when crash occurs, imu's accelerometer may be 4g.  

therefore I set registers below

// use feature engine

FEATURE_IO2 = 0x012C

FEATURE_IO_STATUS = 0x0001

FEATURE_CONTROL = 0x0001

// normal mode on

ACCL_CONF = 0x42a8 //acc_mode = normal mode, bw : odr/4, acc_range : 8g, acc_odr :100Hz

GYRO_CONF = 0x0000

// any motion setting

EXT_ANYMO_1 = 0x1800 // acc_thres : 4g

FEATURE_IO0 = 0x0038 // any motion x,y,z int enable

FEATURE_IO_STATUS = 0x0001

// interrupt

INT_MAP1 = 0x0004 // interrupt mapping, any motion out: INT1

IO_INT_CTRL = 0x0005 // INT1 active high, push-pull, enable

GEN_SET_1 = 0x0011 // event report mode enable, interrupt hold time duration : 40ms

it doesn't work. there's no interrupt while I swing board with imu

if acc_thres is under 10/512g, interrupt happen

I don't understand why this works like that

plz help me. I want to detect crash using  bmi 323

[FAE_CA1]

Hi,

Thanks for your inquiry.

In your code you did not configure BMI323 accel slope (any-motion) interrupt threshold. Please refer to Github example at https://github.com/boschsensortec/BMI323_SensorAPI/blob/main/examples/any_motion/any_motion.c for more information.

Thanks.

[gunbu99]

sorry but I don't get it

in EXT.ANYMO_1 register, I set slope_thres as 4g and in INT_MAP1 register, I set anymotion out

plz refer me what register you said. 

thanks

[FAE_CA1]

Hi,

Yes, you did set the threshold to 4g, I did not see it. Sorry.

Let me try your settings on BMI323 shuttle board to see if any-motion interrupt works or not. I will get back to you later.

Thanks.

[gunbu99]

As I said, interrupt happens when I set slope_thres as 10/512g in EXT.ANYMO_1.

I just don't understand why bmi323 is working like that.

I think that if slope_thres is 10/512g, interrupt happens even though it shake a very little. but in actual situation, interrupt happens when I swing it very hardly.

plz answer and explain how anymotion works.

that's the point I don't understand.