- Mon Aug 20, 2018 7:17 am
#200084
Hi,
I purchased two LIS3DH breakouts and is reading data out of them with a MCU using I2C. All is well until I set the full scale to +-16g.
Based on the datasheet (https://cdn.sparkfun.com/assets/b/c/1/3 ... 274221.pdf), on page 10 under Mechanical Characteristics --> Sensitivity, when the FS bits are set to 11 (+-16g) and in low power mode, each acceleration data's bit represent 192mg. Since low power mode means 8-bit data output, the maximum value that can appear in the 8-bit register is 127 (data is 2's complement). However, a 127 output means an acceleration of 127*192mg = 24.384g. This is greater than the claimed threshold of +-16g.
Does this mean that in low power mode and +-16g full scale, the value of the data register can never exceed 16000mg/192mg = 83? I am getting values such as 127 which don't make sense to me.
I believe my register settings are correct, because when I place the accelerometer flat on the floor, I get 5 on the Z axis, which is 5*192mg = 960mg, which is pretty close to 1g (not 1g since the resolution is low).
Regards,
Kevin S
I purchased two LIS3DH breakouts and is reading data out of them with a MCU using I2C. All is well until I set the full scale to +-16g.
Based on the datasheet (https://cdn.sparkfun.com/assets/b/c/1/3 ... 274221.pdf), on page 10 under Mechanical Characteristics --> Sensitivity, when the FS bits are set to 11 (+-16g) and in low power mode, each acceleration data's bit represent 192mg. Since low power mode means 8-bit data output, the maximum value that can appear in the 8-bit register is 127 (data is 2's complement). However, a 127 output means an acceleration of 127*192mg = 24.384g. This is greater than the claimed threshold of +-16g.
Does this mean that in low power mode and +-16g full scale, the value of the data register can never exceed 16000mg/192mg = 83? I am getting values such as 127 which don't make sense to me.
I believe my register settings are correct, because when I place the accelerometer flat on the floor, I get 5 on the Z axis, which is 5*192mg = 960mg, which is pretty close to 1g (not 1g since the resolution is low).
Regards,
Kevin S