Hello, currently I am conducting PPS signal testing. Referencing the document "UG10143" and its section 6.5.7.1, the kernel is a custom kernel built using flex-build.
By using the command "cat /sys/class/pps/pps0/assert", the timestamp of the eno0 network interface can be captured. However, upon testing, when using an oscilloscope to capture the 1588_PULSE_OUT2 pin, no PPS signal was observed. How should the following sentence in the document be understood?
External trigger signal
To use the actual external trigger pin for signal input on the board. The signal multiplexing should be configured properly, through RCW, or/and FPGA/CPLD. Refer to specific SoC and board reference manuals for that.
Does it mean that the RCW needs to be modified so that only 1588_PULSE_OUT2 can be used for multiplexing in order to be able to capture on the pin? If it's not just about modifying here, could you please explain how to make the modification so that the PPS signal can be captured on this pin? Please be as detailed as possible. Thank you.
LS1028A does support PPS output on 1588_PULSE_OUT2 . However, to observe the PPS signal on J12 of the LS1028ARDB , all of the following must be in place:
- RCW setting :
EC1_SAI3_6_PMUX = 0b101 - Correct 1588 timer configuration
- Proper board-level mux/CPLD routing
Also note that the default PPS pulse width may be only about 10 ns , so it can be easy to miss on the oscilloscope if the trigger or time scale is not set appropriately.