I have a BeagleBone Black configured with U-Boot overlays for PPS input on header pin 9.12 and UART4 on 9.11 and 9.13. This is being fed from an AdaFruit Ultimate GPS breakout board.
Excerpt from /boot/uEnv.txt uboot_overlay_addr0=/lib/firmware/NF3H-PPS-00A0.dtbo uboot_overlay_addr1=/lib/firmware/BB-UART4-00A0.dtbo No other mods were made to uEnv.txt. Initially when I set it up, all appeared good, with the PPS input getting assigned to /dev/pps0 Then all of a sudden on my last reboot the PPS input started getting assigned to /dev/pps1 and serial4 getting assigned to /dev/pps0 I noticed something like this before I installed the latest BBB debian image but dismissed it. Now that I see it again I have questions as to what is causing it. I need to be able to reliably predict what PPS device is getting assigned, as this BBB is being set up as a GPS NTP server using GPSD and Chrony. See dmesg output below. [ 17.330602] pps_ldisc: PPS line discipline registered [ 17.332357] pps pps0: new PPS source serial4 [ 17.332431] pps pps0: source "/dev/ttyS4" added Then later in dmesg output... [ 26.246745] pps pps1: new PPS source ocp:bs_pinmode_P9_12_0x27_pinm [ 26.246871] pps pps1: Registered IRQ 88 as PPS source Does anybody have any ideas as to what is causing this? The uEnv.txt mods above are the only system changes made other than doing apt-gets to install the necessary debian packages for ppstools, gpsd, man-db, and chrony. I also had to build and "make install" chrony from source in order to get PPS support built in. If the answer is that it'll always be /dev/pps1 I'm OK with that. It's just that it has flopped around on me a couple of times now for reasons I don't understand. Now when I power-cycle or reboot the BBB, the chrony service will not start because it fails to open /dev/pps1 yet when I do a ppstest /dev/pps1 I see the PPS input coming in. Almost as if during startup the chrony service is trying to access /dev/pps1 before it is ready. If I then start chrony manually with systemctl start chrony, it starts up successfully. debian@beaglebone:~$ uname -a Linux beaglebone 4.4.91-ti-r133 #1 SMP Tue Oct 10 05:18:08 UTC 2017 armv7l GNU/Linux -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/c33a66f2-6138-47e4-9f54-f6188a268ee8%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
