I’m currently working on a Nvidia Jetson TX2 with Ubuntu 18, using an Emlid Reach GPS Module which is capable of provide NMEA messages through a TCP connection and a 1-PPS signal through a UART pin.
I’m not being able to correctly sync the system clock with the GPS clock.
I was able to compile the linux kernel with the required PPS flags:
CONFIG_PPS=y CONFIG_PPS_DEBUG=y CONFIG_PPS_CLIENT_KTIMER=y CONFIG_PPS_CLIENT_LDISC=y CONFIG_PPS_CLIENT_GPIO=y
And I managed to correctly expose a GPIO pin (modifying the kernel dts), obtaining two devices: /dev/pps0 and /dev/pps1. pps0 corresponds to the kernel PPS and pps1 is a PPS related to a GPIO pin in the board.
The GPS module is connected with a USB cable but provides data by creating a USB-To-Ethernet interface and responding on IP 192.168.2.15, TCP port for data acquisition is configurable and set at port 9001. The PPS signal is connected to a pin in the jetson.
My issue is that some gps/pps tools give me satisfactory results while others fail horribly.
Testing both pps signals:
sudo ppstest /dev/pps0 sudo ppstest /dev/pps1
Gives satisfactory results:
trying PPS source "/dev/pps0" found PPS source "/dev/pps0" ok, found 1 source(s), now start fetching data... source 0 - assert 1657740302.347287559, sequence: 6590 - clear 0.000000000, sequence: 0 ...
But the ppscheck tool doesn’t and fails with:
$ sudo ppscheck /dev/pps0 # Seconds nanoSecs Signals PPS ioctl(TIOCMIWAIT) failed: 25 Inappropriate ioctl for device
gpsmon is able to get the NMEA data from the TCP connection but not the PPS, the PPS line remains blank with:
sudo gpsmon -D 5 192.168.2.15:9001:/dev/pps0
On the other hand trying to configure gpsd fails, using:
sudo gpsd -D 5 -N -n tcp://192.168.2.15:9001 gpsd:INFO: launching (Version 3.17) gpsd:IO: opening IPv4 socket gpsd:ERROR: can't bind to IPv4 port gpsd, Address already in use gpsd:ERROR: maybe gpsd is already running!
Trying with the GPS PPS, /dev/pps1 gives me same results.
Which would be the proper way to configure gpsd to take NMEA data from a TCP connection + a device PPS signal?
Does anyone has some information on that PPS “Inappropriate ioctl for device” error?