Spatial FOG Reference Manual
Page 86 of 144
Version 2.3
03/05/2018
Digital Input
All
Set Zero Orientation Alignment
Digital Input
All
Digital Input
All
Digital Input
All
RTCM Diferential GNSS Corrections Input Serial Receive
2
Receive
Serial Receive
2
Receive
Serial Receive
2
Receive
Serial Receive
2
Receive
Frequency Input All
Frequency Input All
Frequency Input All
Frequency Input All
Frequency Input All
Frequency Input All
Digital Input
All
Digital Input
All
Serial Transmit
1
Transmit
Serial Transmit
1
Transmit
Serial Transmit
1
Transmit
Serial Port Pass-through Packet
Serial
All
All
Frequency Input All
Frequency Input All
Odometer Direction, Forward Low
Digital Input
All
Odometer Direction, Forward High
Digital Input
All
Nortek DVL Binary Format Input
Serial Receive
2
Receive
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.