signalk-hwt901b-imu

SignalK node server plugin (BETA) reading roll, pitch and magnetic heading from WITMOTION's HWT910B sensor

INPUT:

as of device data sheet and own testing, cable plug respresenting the boat's stern:
0x55 0x53 PitchL PitchH RollL RollH YawL YawH VL VH SUM

CALCULATION：

• Pitch (x axis):
  ((PitchH<<8)|PitchL)/32768*180(°) plus an offset determined after calibration and install
• Roll (y axis):
  ((RollH<<8)|RollL)/32768*180(°) plus an offset determined after calibration and install
• Yaw (z axis):
  ((YawH<<8)|YawL)/32768*180(°)
• Version：
  (VH<<8)|VL
• Checksum：
  SUM=0x55+0x53+RollH+RollL+PitchH+PitchL+YawH+YawL+VH+VL (least significant byte must match SUM)
• Magnetic Heading:
  z axis value (yaw) plus an offset determined after calibration and install

PROCESSING:

• Gyroscope has to be calibrated by wit motion windows software prior to final placement onboard
• acceleration calibration, as well as levelling pitch & roll can be accomplished via the plugin's settings

OUTPUT TO SIGNALK (in rad):

{"updates":[{"$source":"WIT.n",
             "values":
               [{"path": "navigation.headingMagnetic",
                         "value":123.456},
                {"path": "navigation.attitude",
                         "value":{"roll":0.123456,
                         "pitch":-0.123456,
                         "yaw":null}}
                ]
            }]
}