Crossbow Technology AHRS400 Series - AHRS Output Quick Reference; Analog Output Conversion; Digital Output Conversion

AHRS400 Series User’s Manual
Page 24 Doc# 7430-0004-01 Rev. A
6 Appendix B. AHRS Output Quick Reference
GR is the G-range of the accelerometers. For example, if your DMU has ±
2 G accelerometers, GR = 2.
RR is the rate range of the rate sensors. For example, if your DMU has ±
100°/s rate sensors, RR = 100.
6.1 Analog Output Conversion
Accelerometer
Use sensitivity, offset from
calibration sheet. Output is raw
sensor voltage.
Rate Sensor
Rate (°/s) =
V
out
(V) * RR * 1.5/4.096
Pin 5 X axis accelerometer, raw Pin 8 Roll rate sensor
Pin 6 Y axis accelerometer, raw Pin 9 Pitch rate sensor
Pin 7 Z axis accelerometer, raw Pin 10 Yaw rate sensor
Magnetometer (Scaled Mode)
Mag (Gauss) =
V
out
(V) * 1.25 * 1.5/4.096
Roll, Pitch, Yaw (Angle Mode)
Angle (°) = V
out
(V) * FA/4.096
Pin 12 X axis magnetometer Pin 12 Roll Angle FA = 180
Pin 13 Y axis magnetometer Pin 13 Pitch Angle FA = 90
Pin 14 Z axis magnetometer Pin 14 Yaw angle FA = 180
6.2 Digital Output Conversion
Data is sent as 16-bit signed integer for all but Temperature. Temperature
sensor data is sent as unsigned integer.
Acceleration
Roll, Pitch, Yaw (Angle Mode)
Accel (G) = data * GR * 1.5/2
15
Angle (°) = data * 180/2
15
Rate Magnetic Field
Rate (°/s) = data * RR * 1.5/2
15
Mag (Gauss) = data * 1.25 * 1.5/2
15
Temperature
Temperature (°C) =
[(data * 5/4096) – 1.375]*44.44
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