Other Parts Discussed in Thread: SK-AM64B
Hi Team,
- SDK:mcu_plus_sdk_am64x_08_06_00_45
- CCS:12.3
- Development board: SK-AM64B
The features are ported from C:\ti\mcu_plus_sdk_am64x_08_06_00_45\examples\networking\enet_layer2_multi_channel
The customer want to achieve time synchronization and sampling synchronization between multiple devices through a standard clock source (based on PTP Layer2) in the network. PPS pulses have been generated using the CPTS GEN feature in CPSW and are output to GPIOs via the TIMSESYNC Router and measured with an oscilloscope. However, the start position of the PPS (rising edge of the pulse) was found to be moving all the time.
PPS path：CPSW(CPTS)->GENF0->TIMESYNC-ROUTER21->GPIO
GENF disable PPM:
As described in the TRM, a pulse is generated when time_STAMP[63-0] = CPTS_GENFn_COMP[63-0], and the period of the pulse is only related to CPTS_GENFn_length[31-0], that is:
A. The PPS generation time is when time_STAMP[63-0] = CPTS_GENFn_COMP[63-0], and once generated, PPS is automatically generated continuously, regardless of the value of time_STAMP[63-0].
B. The period value of PPS is related to CPTS_GENFn_length[31-0], as long as the CPTS_GENFn_length[31-0] value is not modified, the start time (rising edge) of PPS should remain unchanged.
C. CPTS is continuously synchronized with the network time, causing the value of time_stack[63-0] to always be adjusted. However, CPTS_GENFn_length[31-0] is the count CPTS_REF_CLK, so the resulting PPS frequency and period are not affected by the value of time_STAMP[63-0].
Could you help check if the above understanding correct? If so, the rising edges of the PPS pulses from the first two SK pulses are essentially the same, with no skew. After continuous operation, the rising edges of the PPS pulses generated by the two SK's have a significant deviation on the scope. CPTS_REF_CLK appears to be adjusted dynamically because CPTS_GENFn_length[31-0] has not been modified since initialization.
Could you help look into this case? Thanks.
Best Regards,
Cherry
