[LinuxPPS] PPS - Ublox NEO-M9N

[Rodolfo Giometti]

On 12/09/23 08:50, emanuele.pasinetti at tecnowatt.com wrote:
> Good morning,
> 
> I have a problem with GPS module ( AIW-212 – Advantech) Ublox NEO-M9N in 
> minipci-express format, my goal is to get working chrony daemon in combination 
> with gpsd to synchronize my system.
> 
> The device is correctly recognized by OS (Debian 11) and I can trap the NMEA 
> messages on /dev/ttyACM0.
> 
> On system start I can see that also the PPS module is correctly installed :
> 
> dmesg
> 
> [    5.294806] pps_ldisc: PPS line discipline registered
> 
> [    5.295102] pps pps1: new PPS source acm0
> 
> [    5.295109] pps pps1: source "/dev/ttyACM0" added
> 
> When I try to check the pps I can’t see any status changing.
> 
> ppstest /dev/pps1
> 
> trying PPS source "/dev/pps1"
> 
> found PPS source "/dev/pps1"
> 
> ok, found 1 source(s), now start fetching data...
> 
> time_pps_fetch() error -1 (Connection timed out)
> 
> To verify the PPS presence (in addiction to checking the GPS mode (3D FIX) with 
> cgps tool) I have connected a wire soldered to the PPS signal present on module 
> and the DCD signal of an RS232 serial port.
> 
> If I check the PPS with ppscheck tool I think the signal is working correctly.
> 
> ppscheck /dev/ttyS0
> 
> # Seconds  nanoSecs   Signals
> 
> 1694124205.155059987 TIOCM_CD
> 
> 1694124205.254962112
> 
> 1694124206.154989656 TIOCM_CD
> 
> 1694124206.255009871
> 
> 1694124207.155048536 TIOCM_CD
> 
> 1694124207.255041944
> 
> 1694124208.155054413 TIOCM_CD
> 
> 1694124208.255058004
> 
> Why the PPS is not visible on  “/dev/pps1” ?

Before executing the ppstest tool did you execute ldattach to be sure that 
/dev/ttyS0's line discipline is correctly set to PPS?

Ciao,

Rodolfo

-- 
GNU/Linux Solutions                  e-mail: giometti at enneenne.com
Linux Device Driver                          giometti at linux.it
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