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</o:shapelayout></xml><![endif]--></head><body lang=ZH-CN link=blue vlink=purple style='text-justify-trim:punctuation'><div class=WordSection1><p class=MsoNormal><span lang=EN-US>When I run the /example/rtai_rtdm_dc. Why the system_time_base is less than zero for sometimes. Than the master will report error message ““Synchronization error”” ,the AL status code is 0x001A.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>The code is following:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US>void update_master_clock(void)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>{<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>#if SYNC_MASTER_TO_REF<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> // calc drift (via un-normalised time diff)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> int32_t delta = dc_diff_ns - prev_dc_diff_ns;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> prev_dc_diff_ns = dc_diff_ns;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> // normalise the time diff<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_diff_ns =<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> ((dc_diff_ns + (cycle_ns / 2)) % cycle_ns) - (cycle_ns / 2);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> // only update if primary master<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> if (dc_started) {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> // add to totals<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_diff_total_ns += dc_diff_ns;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_delta_total_ns += delta;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_filter_idx++;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> if (dc_filter_idx >= DC_FILTER_CNT) {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> // add rounded delta average<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_adjust_ns +=<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> ((dc_delta_total_ns + (DC_FILTER_CNT / 2)) / DC_FILTER_CNT);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> // and add adjustment for general diff (to pull in drift)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_adjust_ns += sign(dc_diff_total_ns / DC_FILTER_CNT);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> // limit crazy numbers (0.1% of std cycle time)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> if (dc_adjust_ns < -1000) {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_adjust_ns = -1000;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> }<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> if (dc_adjust_ns > 1000) {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_adjust_ns = 1000;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> }<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> // reset<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_diff_total_ns = 0LL;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_delta_total_ns = 0LL;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_filter_idx = 0;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> }<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> // add cycles adjustment to time base (including a spot adjustment)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> system_time_base += dc_adjust_ns + sign(dc_diff_ns);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> }<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> else {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_started = (dc_diff_ns != 0);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> if (dc_started) {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> // output first diff<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> rt_printk("First master diff: %d.\n", dc_diff_ns);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> // record the time of this initial cycle<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> dc_start_time_ns = dc_time_ns;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US> }<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>}<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US> When system_time_base is less than zero ,the master can not be sync to the ref clock slave.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US>But I do not know ,why the system_time_base can be less than zero?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p></div></body></html>