Data Sheet

Sensor Documentation Modern Robotics, Inc.
Version 1.4.3 17
Accelerometer Scale Coefficient:
The Accelerometer Scale Coefficient is adjusted to be approximately 1mg/count. If
greater measurement accuracy is required, the Accelerometer Scale Coefficient (fsb/lsb)
may be set by the user. This can be simply done by setting the device perfectly vertical
and obtaining the accelerometer X value via registers 0x06 and 0x07. If the value read
were to be 850, then the
Once the Accelerometer Scale Coefficient has been adjusted, the 0x57 command should
be issued to ensure the new value is recorded in EEPROM.
Example:
Step 1: Sensor Position
Set the sensor vertical so that the wires are pointing up in the air.
Step 2: Find the X Value
Find the Accelerometer X Value - Register 0x06 (lsb)/0x07 (msb)
Register 0x06 (lsb) = 0xE2
Register 0x07 (msb) = 0x04
X Value = msb:lsb = 0x04:0xE2 = 0x04E2 = 1250
Step 3: Calculate Scaling Value
Scaling Value = 1000/X Value = 1000/1250 = .8
Step 4: Calculate Register Values
Register Value (lsb:fsb) = .8 * 256 = 204.8 = 204 = 0xCC = 0x00CC
Step 5: Enter Values into Accelerometer Scale Coefficient Register
Accelerometer Scale Coefficient = 0x20 (fsb)/0x21 (lsb)
Register 0x20 (fsb) = 0xCC
Register 0x21 (lsb) = 0x00
Step 6: Saving the value to EEPROM
Enter a value of 0x57 (Write EEPROM Data) to the Command Register (0x03) to save the
scaled value into EEPROM.