Hello there,
I am attempting to extend our existing PTP timing solution to use NTP and GPS as well, using a Beaglebone Black. I intend for Linux to synchronise the system clock to UTC via either PTP (LinuxPTPd), GPS (GPSd+ntpd) or NTP (ntpd). I was thinking of using some form of realtime Linux to generate a 1PPS and 200Hz signal but the jitter will be rather high. I then discovered the PRU and have spent the last hours looking at it, and realising the scale of the project - its not an evenings work!
Rather than dive in and spend a lot of time developing it only to find I run into some limitations, I would first like to know from any experts here if it is possible to read the system time from Linux in the PRU (without too much penalty to Linux) and generate the clock pulses. I expect that I would use the Linux clock that is reported on by 'gettimeofday()' and toggle IO lines whenever 5ms intervals occur, and whenever 1000ms intervals occur. The jitter should be acceptably low - I am driving a PLL with a fairly slow time constant.
Is this possible to read the system time used by Linux? Any ideas? Advice? All of which would be gratefully accepted!
Kind regards and many thanks,
Hamish
