IIS2DLPC accelerometer data conversion

[Myles]

Hi：

According to the IIS2DLPC datasheet and STMems_Standard_C_drivers are as follows

https://github.com/STMicroelectronics/iis2dlpc-pid/blob/cb5a10d963790fbe8863d4fd9449f8e00ed3cb8a/iis2dlpc_reg.c

 

According to the IIS2DLPC datasheet, it seems that the iis2dlpc_reg.c needs to be corrected, such as the red text comment?

float_t iis2dlpc_from_fs2_to_mg(int16_t lsb)
{
return ((float_t)lsb) * 0.061f;
//return ((float_t)lsb) * 0.244f;
}

float_t iis2dlpc_from_fs4_to_mg(int16_t lsb)
{
return ((float_t)lsb) * 0.122f;
//return ((float_t)lsb) * 0.488f;
}

float_t iis2dlpc_from_fs8_to_mg(int16_t lsb)
{
return ((float_t)lsb) * 0.244f;
//return ((float_t)lsb) * 0.976f;
}

float_t iis2dlpc_from_fs16_to_mg(int16_t lsb)
{
return ((float_t)lsb) * 0.488f;
//return ((float_t)lsb) * 1.952f;
}

float_t iis2dlpc_from_fs2_lp1_to_mg(int16_t lsb)
{
return ((float_t)lsb) * 0.061f;
//return ((float_t)lsb) * 0.976f;
}

float_t iis2dlpc_from_fs4_lp1_to_mg(int16_t lsb)
{
return ((float_t)lsb) * 0.122f;
//return ((float_t)lsb) * 1.952f;
}

float_t iis2dlpc_from_fs8_lp1_to_mg(int16_t lsb)
{
return ((float_t)lsb) * 0.244f;
//return ((float_t)lsb) * 3.904f;
}

float_t iis2dlpc_from_fs16_lp1_to_mg(int16_t lsb)
{
return ((float_t)lsb) * 0.488f;
//return ((float_t)lsb) * 7.808f;
}

thanks

 

[Federica Bossi]

Hi @Myles ,

Welcome to ST Community!

Drivers are correct. The coefficient values reported in the PID are considering the sensitivity and the shift of 2/4 bit to have data in right giustified according to the resolution, as written in Datasheet (pg 20 Table 11):

Data are always represented in 16 bit and they need to be shift by 2 or 4 according to the power mode (es: in High Performance mode, FS=2g you need to divide 0.244 by 4 = 0.061).

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[Myles]

I figured it out, thanks for clearing up my doubts!