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Motus Reference Manual
Page 94 of 146
Version 1.1
29/11/2019
15.4.1 1PPS Output
In this function, the pin pulses for 50 milliseconds to signal the precise second. The
1PPS line starts pulsing approximately 100 milliseconds after power up and always
fires irrespective of whether Motus has accurate time or not. It is important to note
that when Motus acquires time corrections from a GNSS receiver, the 1PPS signal may
fire at an interval of less than 1 second. This typically only occurs the first time the
GNSS receiver obtains a fix after startup. The time initialised status flag can be used to
determine whether the time and 1PPS line is accurate or not.
1PPS Source Voltage Level Trigger
Auxiliary -5 V to 5 V Falling Edge
GPIO 0 to 5 V Rising Edge
Table 24: 1PPS Specifications
15.4.2 GNSS Fix Output
In this function, the pin is low when there is no GNSS fix or a 2D fix and high when
there is a 3D, SBAS, Differential or RTK GNSS fix.
15.4.3 Odometer Input
This function is designed for low resolution vehicle speed sensors and odometers. It
expects a normally low input with a high state for the trigger. If the pulse length is
more than 0.1 metres this odometer input function should be used, if it is less than 0.1
metres the wheel speed sensor function should be used. Please contact Advanced
Navigation support for help integrating with your speed sensor.
Parameter Value
Trigger Low → High
Maximum Frequency 600Khz
Maximum Pulse Rate 4294967 pulses/metre
Table 25: Odometer Specifications
15.4.4 Zero Velocity Input
When using this function, a high state indicates to Motus that it is stationary. The low
state indicates that the vehicle is not stationary. Use of this function can significantly
improve drift performance when a GNSS signal is not available.
15.4.5 Pitot Tube Input
This function is designed for fixed wing aircraft to enhance navigation through the use
of a pitot tube to measure airspeed. It requires a differential pressure sensor that has a
frequency output such as the Kavlico P992 (frequency output option) or the
Paroscientific series 5300. Please contact Advanced Navigation support for help
integrating with a pitot tube.