1Pps Output - Advanced Navigation Spatial FOG Reference Manual

Disable Pressure
Set Zero Orientation Alignment
System State Packet Trigger
Raw Sensors Packet Trigger
RTCM Diferential GNSS Corrections Input Serial Receive
Trimble GNSS Input
u-blox GNSS Input
Hemisphere GNSS Input
Left Wheel Speed Sensor
Right Wheel Speed Sensor
1PPS Input
Wheel Speed Sensor
Wheel Encoder Phase A
Wheel Encoder Phase B
Event 1 Input
Event 2 Input
TSS1 Output
Simrad 1000 Output
Simrad 3000 Output
Serial Port Pass-through Packet
Gimbal Encoder Phase A
Gimbal Encoder Phase B
Odometer Direction, Forward Low
Odometer Direction, Forward High
Nortek DVL Binary Format Input
Table 18: GPIO pin functions
12.4.1

1PPS Output

In this function, the pin is normally low and pulses high 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 Spatial FOG has accurate time or
not. It is important to note that when Spatial FOG acquires time corrections from it's
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 fag can be used to determine whether the time and 1PPS line is
accurate or not.
Spatial FOG Reference Manual
Page 86 of 144
03/05/2018
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