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How to access the TIMER3 in wireless timer sync?

Hello,

I found this great blog entry about synchronizing timers on different devices: https://devzone.nordicsemi.com/nordic/short-range-guides/b/bluetooth-low-energy/posts/wireless-timer-synchronization-among-nrf5-devices

It works just fine on a nRF52840DK and a nRF52DK. Timers on multiple nRF5 devices are synced by one device (master) sending sync packets containing captured timer values to other devices (nodes). (TIMER3 is free running, TIMER2 counts TIMER3 overflows).

At the moment I am struggeling to access this synchronized TIMER3 on the two boards. I am familiar with setting up a TIMER without wireless timer sync.

So here are my questions:

1. How can I define CC, Prescaler, Mode, Bitmode, the interrupt handler and so forth when using wireless timer sync?

2. Can anybody provide me some advice how to access this synchronized TIMER3 properly?

Thank you very much in advance.

0 Michael01101 over 4 years ago in reply to Audun

Hello Audun,

thank you very much for your detailed reply. I really appreciate your help.

Audun said:
which means there either isn't any more sync packets from the transmitter received, or that there is an issue with appying a received packet.

This is caused by the procedure how I catched the offset in my previous reply. I generated an error at the central when the offset occurs to catch the relevant debug data. So the central stopped transmitting sync beacons when the offset occured.

I swapped my previous timers_capture() function with your timers_capture() function. Unfortunately, this does not solve the offset issue.

You can see the debug logs for the peripheral and the central in the following. These logs are generated with your recommended timers_capture() function. I also delayed the generation of the error on my central when the offset occurs. So the central does not stop immediatly transmitting sync beacons. Instead the central continues sending sync beacons for ~560ms after the offset occured before the central stops itself.

--------------------------------------------------------------

Peripheral

This is the debug log on the peripheral side.

[00:05:18.499,877] [00:05:18.539,855] <info> time_sync: 39608, 8, 539588 [00:05:18.579,895] <info> time_sync: 39607, 24, 539588 [00:05:18.619,873] <info> time_sync: 39620, 1, 539627 [00:05:18.659,851] <info> time_sync: 39625, 4, 539640 [00:05:18.699,890] <info> time_sync: 39630, 7, 539653 [00:05:18.739,868] <info> time_sync: 39634, 10, 539666 [00:05:18.779,907] <info> time_sync: 39634, 26, 539666 [00:05:18.819,885] <info> time_sync: 39648, 3, 539705 [00:05:18.859,863] <info> time_sync: 39653, 6, 539718 [00:05:18.899,902] <info> time_sync: 39657, 9, 539731 [00:05:18.939,880] <info> time_sync: 39657, 25, 539731 [00:05:18.979,919] <info> time_sync: 39672, 2, 539770 [00:05:19.019,897] <info> time_sync: 39675, 5, 539783 [00:05:19.059,875] <info> time_sync: 39680, 8, 539796 [00:05:19.099,914] <info> time_sync: 39680, 24, 539796 [00:05:19.139,892] <info> time_sync: 39694, 1, 539835 [00:05:19.179,931] <info> time_sync: 39698, 4, 539848 [00:05:19.219,909] <info> time_sync: 39703, 7, 539861 [00:05:19.259,887] <info> time_sync: 39707, 10, 539874 [00:05:19.299,926] <info> time_sync: 39707, 26, 539874 [00:05:19.339,904] <info> time_sync: 39721, 3, 539913 [00:05:19.379,882] <info> time_sync: 39726, 6, 539926 [00:05:19.419,921] <info> time_sync: 39731, 9, 539939 [00:05:19.459,899] <info> time_sync: 39730, 25, 539939 [00:05:19.499,938] <info> time_sync: 39744, 2, 539978 [00:05:19.539,916] <info> time_sync: 39748, 5, 539991 [00:05:19.579,895] <info> time_sync: 39753, 8, 540004 [00:05:19.619,934] <info> time_sync: 39753, 24, 540004 [00:05:19.659,912] <info> time_sync: 39767, 1, 540043 [00:05:19.699,951] <info> time_sync: 39771, 4, 540056 [00:05:19.739,929] <info> time_sync: 39776, 7, 540069 [00:05:19.779,907] <info> time_sync: 39781, 10, 540082 [00:05:19.819,946] <info> time_sync: 39781, 26, 540082 [00:05:19.859,924] <info> time_sync: 39795, 3, 540121 [00:05:19.899,963] <info> time_sync: 39799, 6, 540134 [00:05:19.939,941] <info> time_sync: 39803, 9, 540147 [00:05:19.979,919] <info> time_sync: 39803, 25, 540147 [00:05:20.019,958] <info> time_sync: 39818, 2, 540186 [00:05:20.059,936] <info> time_sync: 39822, 5, 540199 [00:05:20.099,975] <info> time_sync: 39826, 8, 540212 [00:05:20.139,953] <info> time_sync: 39826, 24, 540212 [00:05:20.179,931] <info> time_sync: 39840, 1, 540251 [00:05:20.219,970] <info> time_sync: 39844, 4, 540264 [00:05:20.259,948] <info> time_sync: 39849, 7, 540277 [00:05:20.299,926] <info> time_sync: 39854, 10, 540290 [00:05:20.339,965] <info> time_sync: 39853, 26, 540290 [00:05:20.379,943] <info> time_sync: 39867, 3, 540329 [00:05:20.419,982] <info> time_sync: 39872, 6, 540342 [00:05:20.459,960] <info> time_sync: 39876, 9, 540355 [00:05:20.499,938] <info> time_sync: 39876, 25, 540355 [00:05:20.539,978] <info> time_sync: 39890, 2, 540394 [00:05:20.579,956] <info> time_sync: 39895, 5, 540407 [00:05:20.619,995] <info> time_sync: 39900, 8, 540420 [00:05:20.659,973] <info> time_sync: 39900, 24, 540420 [00:05:20.699,951] <info> time_sync: 39913, 1, 540459 [00:05:20.739,990] <info> time_sync: 39918, 4, 540472 [00:05:20.779,968] <info> time_sync: 39922, 7, 540485 [00:05:20.820,007] <info> time_sync: 39927, 10, 540498 [00:05:20.859,985] <info> time_sync: 39927, 26, 540498 [00:05:20.899,963] <info> time_sync: 39940, 3, 540537 [00:05:20.940,002] <info> time_sync: 39945, 6, 540550 [00:05:20.979,980] <info> time_sync: 39949, 9, 540563 [00:05:21.020,019] <info> time_sync: 39949, 25, 540563 [00:05:21.059,997] <info> time_sync: 39964, 2, 540602 [00:05:21.099,975] <info> time_sync: 39968, 5, 540615 [00:05:21.140,014] <info> time_sync: 39972, 8, 540628 [00:05:21.179,992] <info> time_sync: 39973, 24, 540628 [00:05:21.219,970] <info> time_sync: 39986, 1, 540667 [00:05:21.260,009] <info> time_sync: 39990, 4, 540680 [00:05:21.299,987] <info> time_sync: 39995, 7, 540693 [00:05:21.340,026] <info> time_sync: 0, 10, 540706 [00:05:21.380,004] <info> time_sync: 0, 26, 540706 [00:05:21.419,982] <info> time_sync: 14, 4, 540745 [00:05:21.460,021] <info> time_sync: 18, 7, 540758 [00:05:21.500,000] <info> time_sync: 23, 10, 540771 [00:05:21.540,039] <info> time_sync: 23, 26, 540771 [00:05:21.580,017] <info> time_sync: 36, 3, 540810 [00:05:21.619,995] <info> time_sync: 42, 6, 540823 [00:05:21.660,034] <info> time_sync: 45, 9, 540836 [00:05:21.700,012] <info> time_sync: 45, 25, 540836 [00:05:21.740,051] <info> time_sync: 59, 2, 540875 [00:05:21.780,029] <info> time_sync: 64, 5, 540888 [00:05:21.820,007] <info> time_sync: 68, 8, 540901 [00:05:21.860,046] <info> time_sync: 73, 11, 540914 [00:05:21.900,024] <info> time_sync: 73, 27, 540914 [00:05:21.940,063] <info> time_sync: 86, 4, 540953 [00:05:21.980,041] <info> time_sync: 74, 20, 540953 [00:05:22.020,019] <info> time_sync: 74, 36, 540953 [00:05:22.060,058] <info> time_sync: 74, 52, 540953 [00:05:22.100,036] <info> time_sync: 74, 68, 540953 [00:05:22.140,014] <info> time_sync: 74, 84, 540953 [00:05:22.180,053] <info> time_sync: 74, 100, 540953 [00:05:22.220,031] <info> time_sync: 74, 116, 540953 [00:05:22.260,070] <info> time_sync: 74, 132, 540953 [00:05:22.300,048] <info> time_sync: 74, 148, 540953 [00:05:22.340,026] <info> time_sync: 74, 164, 540953 [00:05:22.380,065] <info> time_sync: 74, 180, 540953 [00:05:22.420,043] <info> time_sync: 74, 196, 540953 [00:05:22.460,083] <info> time_sync: 74, 212, 540953 [00:05:22.500,061] <info> time_sync: 74, 228, 540953 [00:05:22.540,039] <info> time_sync: 74, 244, 540953 [00:05:22.580,078] <info> time_sync: 74, 260, 540953 [00:05:22.620,056] <info> time_sync: 74, 276, 540953 [00:05:22.660,095] <info> time_sync: 74, 292, 540953 [00:05:22.700,073] <info> time_sync: 74, 308, 540953 [00:05:22.740,051] <info> time_sync: 74, 324, 540953 [00:05:22.780,090] <info> time_sync: 74, 340, 540953 [00:05:22.820,068] <info> time_sync: 74, 356, 540953 [00:05:22.860,046] <info> time_sync: 74, 372, 540953 [00:05:22.900,085] <info> time_sync: 74, 388, 540953 [00:05:22.940,063] <info> time_sync: 74, 404, 540953 [00:05:22.980,102] <info> time_sync: 74, 420, 540953 [00:05:23.020,080] <info> time_sync: 74, 436, 540953 [00:05:23.060,058] <info> time_sync: 74, 452, 540953 [00:05:23.100,097] <info> time_sync: 74, 468, 540953 [00:05:23.140,075] <info> time_sync: 74, 484, 540953 [00:05:23.180,114] <info> time_sync: 74, 500, 540953 [00:05:23.220,092] <info> time_sync: 74, 516, 540953

<info> time_sync: 39602, 5, 539575    timestamp: 1348952 timestamp: 1348992 timestamp: 1349032 timestamp: 1349072 timestamp: 1349112 timestamp: 1349152 timestamp: 1349192 timestamp: 1349232 timestamp: 1349272 timestamp: 1349312 timestamp: 1349352 timestamp: 1349392 timestamp: 1349432 timestamp: 1349472 timestamp: 1349512 timestamp: 1349552 timestamp: 1349592 timestamp: 1349632 timestamp: 1349672 timestamp: 1349712 timestamp: 1349752 timestamp: 1349792 timestamp: 1349832 timestamp: 1349872 timestamp: 1349912 timestamp: 1349952 timestamp: 1349992 timestamp: 1350032 timestamp: 1350072 timestamp: 1350112 timestamp: 1350152 timestamp: 1350192 timestamp: 1350232 timestamp: 1350272 timestamp: 1350312 timestamp: 1350352 timestamp: 1350392 timestamp: 1350432 timestamp: 1350472 timestamp: 1350512 timestamp: 1350552 timestamp: 1350592 timestamp: 1350632 timestamp: 1350672 timestamp: 1350712 timestamp: 1350752 timestamp: 1350792 timestamp: 1350832 timestamp: 1350872 timestamp: 1350912 timestamp: 1350952 timestamp: 1350992 timestamp: 1351032 timestamp: 1351072 timestamp: 1351112 timestamp: 1351152 timestamp: 1351192 timestamp: 1351232 timestamp: 1351272 timestamp: 1351312 timestamp: 1351352 timestamp: 1351392 timestamp: 1351432 timestamp: 1351472 timestamp: 1351512 timestamp: 1351552 timestamp: 1351592 timestamp: 1351632 timestamp: 1351672 timestamp: 1351712 timestamp: 1351752 timestamp: 1351790 timestamp: 1351830 timestamp: 1351873 timestamp: 1351913 timestamp: 1351953 timestamp: 1351993 timestamp: 1352033 timestamp: 1352073 timestamp: 1352113 timestamp: 1352153 timestamp: 1352193 timestamp: 1352233 timestamp: 1352273 timestamp: 1352313 timestamp: 1352353 timestamp: 1352393 timestamp: 1352433 timestamp: 1352473 timestamp: 1352513 timestamp: 1352553 timestamp: 1352593 timestamp: 1352633 timestamp: 1352673 timestamp: 1352713 timestamp: 1352753 timestamp: 1352793 timestamp: 1352833 timestamp: 1352873 timestamp: 1352913 timestamp: 1352953 timestamp: 1352993 timestamp: 1353033 timestamp: 1353073 timestamp: 1353113 timestamp: 1353153 timestamp: 1353193 timestamp: 1353233 timestamp: 1353273 timestamp: 1353313 timestamp: 1353353 timestamp: 1353393 timestamp: 1353433 timestamp: 1353473 timestamp: 1353513 timestamp: 1353553 timestamp: 1353593 timestamp: 1353633 timestamp: 1353673

You can see that the offset happened in line 72. We can also see that the peripheral still receives the beacon sync pakets until line 87. At this point the central stops sending sync beacons as a consequence of the selfmade error to catch the relevant debug data. So the peripheral can not receive any sync beacon pakets anymore, because there are none.

It is also interesting that the offset occures when the sync_timer_val goes to zero.

--------------------------------------------------------------

Central

This is the debug log on the central side. The debug log is the corresponding one to debug log of the peripheral, which I descriped a few lines earlier.

This is pretty much the same as in my previous reply.

<info> time_sync: 32680, 540718, 0    timestamp: 1351797
<info> time_sync: 8651, 540719, 0    timestamp: 1351798
<info> time_sync: 16656, 540722, 0    timestamp: 1351806
<info> time_sync: 32656, 540722, 0    timestamp: 1351807
<info> time_sync: 8656, 540723, 0    timestamp: 1351808
<info> time_sync: 24656, 540723, 0    timestamp: 1351809
<info> time_sync: 656, 540724, 0    timestamp: 1351810
<info> time_sync: 16656, 540724, 0    timestamp: 1351811
<info> time_sync: 32656, 540724, 0    timestamp: 1351812
<info> time_sync: 8656, 540725, 0    timestamp: 1351813
<info> time_sync: 24656, 540725, 0    timestamp: 1351814
<info> time_sync: 656, 540726, 0    timestamp: 1351815
<info> time_sync: 16656, 540726, 0    timestamp: 1351816
<info> time_sync: 32656, 540726, 0    timestamp: 1351817
<info> time_sync: 8656, 540727, 0    timestamp: 1351818
<info> time_sync: 24656, 540727, 0    timestamp: 1351819
<info> time_sync: 656, 540728, 0    timestamp: 1351820
<info> time_sync: 16656, 540728, 0    timestamp: 1351821
<info> time_sync: 32657, 540728, 0    timestamp: 1351822
<info> time_sync: 8656, 540729, 0    timestamp: 1351823
<info> time_sync: 24656, 540729, 0    timestamp: 1351824
<info> time_sync: 656, 540730, 0    timestamp: 1351825
<info> time_sync: 32657, 540730, 0    timestamp: 1351827
<info> time_sync: 8647, 540731, 0    timestamp: 1351828
<info> time_sync: 24657, 540731, 0    timestamp: 1351829
<info> time_sync: 656, 540732, 0    timestamp: 1351830
<info> time_sync: 16656, 540732, 0    timestamp: 1351831
<info> app: diff: 38
<info> time_sync: 34937, 540732, 0    timestamp: 1351832
<info> app: Zeit bei Emfpfang: 1351832 ms
<info> time_sync: 37943, 540732, 0    timestamp: 1351832
<info> time_sync: 8654, 540733, 0    timestamp: 1351833
<info> time_sync: 24770, 540733, 0    timestamp: 1351834
<info> time_sync: 733, 540734, 0    timestamp: 1351835
<info> time_sync: 16680, 540734, 0    timestamp: 1351836
<info> time_sync: 32728, 540734, 0    timestamp: 1351837
<info> time_sync: 8648, 540735, 0    timestamp: 1351838
<info> time_sync: 32656, 540738, 0    timestamp: 1351847
<info> time_sync: 8656, 540739, 0    timestamp: 1351848
<info> time_sync: 24656, 540739, 0    timestamp: 1351849
<info> time_sync: 656, 540740, 0    timestamp: 1351850
<info> time_sync: 16656, 540740, 0    timestamp: 1351851
<info> time_sync: 32656, 540740, 0    timestamp: 1351852
<info> time_sync: 8656, 540741, 0    timestamp: 1351853
<info> time_sync: 24656, 540741, 0    timestamp: 1351854
<info> time_sync: 656, 540742, 0    timestamp: 1351855
<info> time_sync: 16656, 540742, 0    timestamp: 1351856
<info> time_sync: 32656, 540742, 0    timestamp: 1351857
<info> time_sync: 8656, 540743, 0    timestamp: 1351858
<info> time_sync: 24656, 540743, 0    timestamp: 1351859
<info> time_sync: 656, 540744, 0    timestamp: 1351860
<info> time_sync: 16655, 540744, 0    timestamp: 1351861
<info> time_sync: 32656, 540744, 0    timestamp: 1351862
<info> time_sync: 8655, 540745, 0    timestamp: 1351863
<info> time_sync: 24657, 540745, 0    timestamp: 1351864
<info> time_sync: 647, 540746, 0    timestamp: 1351865
<info> time_sync: 16656, 540746, 0    timestamp: 1351866
<info> time_sync: 32656, 540746, 0    timestamp: 1351867
<info> time_sync: 24657, 540747, 0    timestamp: 1351869
<info> time_sync: 647, 540748, 0    timestamp: 1351870
<info> time_sync: 16657, 540748, 0    timestamp: 1351871
<info> app: diff: 40
<info> time_sync: 37541, 540748, 0    timestamp: 1351872
<info> time_sync: 8804, 540749, 0    timestamp: 1351873
<info> time_sync: 24655, 540749, 0    timestamp: 1351874
<info> time_sync: 716, 540750, 0    timestamp: 1351875
<info> time_sync: 16697, 540750, 0    timestamp: 1351876
<info> time_sync: 32655, 540752, 0    timestamp: 1351882
<info> time_sync: 8656, 540753, 0    timestamp: 1351883
<info> time_sync: 24656, 540753, 0    timestamp: 1351884
<info> time_sync: 656, 540754, 0    timestamp: 1351885
<info> time_sync: 16656, 540754, 0    timestamp: 1351886
<info> time_sync: 32656, 540754, 0    timestamp: 1351887
<info> time_sync: 8656, 540755, 0    timestamp: 1351888
<info> time_sync: 24656, 540755, 0    timestamp: 1351889
<info> time_sync: 656, 540756, 0    timestamp: 1351890
<info> time_sync: 16656, 540756, 0    timestamp: 1351891
<info> time_sync: 32656, 540756, 0    timestamp: 1351892
<info> time_sync: 8655, 540757, 0    timestamp: 1351893
<info> time_sync: 24656, 540757, 0    timestamp: 1351894
<info> time_sync: 655, 540758, 0    timestamp: 1351895
<info> time_sync: 16657, 540758, 0    timestamp: 1351896
<info> time_sync: 32647, 540758, 0    timestamp: 1351897
<info> time_sync: 8656, 540759, 0    timestamp: 1351898
<info> time_sync: 24656, 540759, 0    timestamp: 1351899
<info> time_sync: 656, 540760, 0    timestamp: 1351900
<info> time_sync: 16657, 540760, 0    timestamp: 1351901
<info> time_sync: 32647, 540760, 0    timestamp: 1351902
<info> time_sync: 8656, 540761, 0    timestamp: 1351903
<info> time_sync: 24656, 540761, 0    timestamp: 1351904
<info> time_sync: 656, 540764, 0    timestamp: 1351910
<info> time_sync: 16656, 540764, 0    timestamp: 1351911
<info> app: diff: 43
<info> time_sync: 35004, 540764, 0    timestamp: 1351912
<info> app: Zeit bei Emfpfang: 1351912 ms
<info> time_sync: 38010, 540764, 0    timestamp: 1351912
<info> time_sync: 8701, 540765, 0    timestamp: 1351913
<info> time_sync: 24834, 540765, 0    timestamp: 1351914
<info> time_sync: 647, 540766, 0    timestamp: 1351915
<info> time_sync: 16703, 540766, 0    timestamp: 1351916
<info> time_sync: 32825, 540766, 0    timestamp: 1351917
<info> time_sync: 8655, 540767, 0    timestamp: 1351918
<info> time_sync: 24656, 540767, 0    timestamp: 1351919
<info> time_sync: 656, 540770, 0    timestamp: 1351925
<info> time_sync: 16655, 540770, 0    timestamp: 1351926
<info> time_sync: 32656, 540770, 0    timestamp: 1351927
<info> time_sync: 8655, 540771, 0    timestamp: 1351928
<info> time_sync: 24656, 540771, 0    timestamp: 1351929
<info> time_sync: 656, 540772, 0    timestamp: 1351930
<info> time_sync: 16656, 540772, 0    timestamp: 1351931
<info> time_sync: 32656, 540772, 0    timestamp: 1351932
<info> time_sync: 8656, 540773, 0    timestamp: 1351933
<info> time_sync: 24656, 540773, 0    timestamp: 1351934
<info> time_sync: 656, 540774, 0    timestamp: 1351935
<info> time_sync: 16656, 540774, 0    timestamp: 1351936
<info> time_sync: 32656, 540774, 0    timestamp: 1351937
<info> time_sync: 8656, 540775, 0    timestamp: 1351938
<info> time_sync: 24656, 540775, 0    timestamp: 1351939
<info> time_sync: 657, 540776, 0    timestamp: 1351940
<info> time_sync: 16647, 540776, 0    timestamp: 1351941
<info> time_sync: 32656, 540776, 0    timestamp: 1351942
<info> time_sync: 8656, 540777, 0    timestamp: 1351943
<info> time_sync: 24656, 540777, 0    timestamp: 1351944
<info> time_sync: 657, 540778, 0    timestamp: 1351945
<info> time_sync: 16647, 540778, 0    timestamp: 1351946
<info> time_sync: 32656, 540778, 0    timestamp: 1351947
<info> time_sync: 24657, 540779, 0    timestamp: 1351949
<info> time_sync: 647, 540780, 0    timestamp: 1351950
<info> time_sync: 16657, 540780, 0    timestamp: 1351951
<info> app: diff: 40
<info> time_sync: 37450, 540780, 0    timestamp: 1351952
<info> time_sync: 8707, 540781, 0    timestamp: 1351953
<info> time_sync: 24832, 540781, 0    timestamp: 1351954
<info> time_sync: 830, 540782, 0    timestamp: 1351955
<info> time_sync: 16813, 540782, 0    timestamp: 1351956
<info> time_sync: 32760, 540782, 0    timestamp: 1351957
<info> time_sync: 8656, 540785, 0    timestamp: 1351963
<info> time_sync: 24656, 540785, 0    timestamp: 1351964
<info> time_sync: 656, 540786, 0    timestamp: 1351965
<info> time_sync: 16656, 540786, 0    timestamp: 1351966
<info> time_sync: 32656, 540786, 0    timestamp: 1351967
<info> time_sync: 8656, 540787, 0    timestamp: 1351968
<info> time_sync: 24656, 540787, 0    timestamp: 1351969
<info> time_sync: 656, 540788, 0    timestamp: 1351970
<info> time_sync: 16656, 540788, 0    timestamp: 1351971
<info> time_sync: 32656, 540788, 0    timestamp: 1351972
<info> time_sync: 8657, 540789, 0    timestamp: 1351973
<info> time_sync: 24647, 540789, 0    timestamp: 1351974
<info> time_sync: 656, 540790, 0    timestamp: 1351975
<info> time_sync: 16656, 540790, 0    timestamp: 1351976
<info> time_sync: 32656, 540790, 0    timestamp: 1351977
<info> time_sync: 8657, 540791, 0    timestamp: 1351978
<info> time_sync: 24656, 540791, 0    timestamp: 1351979
<info> time_sync: 24656, 540793, 0    timestamp: 1351984
<info> time_sync: 656, 540794, 0    timestamp: 1351985
<info> time_sync: 16656, 540794, 0    timestamp: 1351986
<info> time_sync: 32656, 540794, 0    timestamp: 1351987
<info> time_sync: 8656, 540795, 0    timestamp: 1351988
<info> time_sync: 24656, 540795, 0    timestamp: 1351989
<info> time_sync: 656, 540796, 0    timestamp: 1351990
<info> time_sync: 16656, 540796, 0    timestamp: 1351991
<info> app: diff: 40
<info> time_sync: 37594, 540796, 0    timestamp: 1351992
<info> time_sync: 8654, 540797, 0    timestamp: 1351993
<info> time_sync: 24749, 540797, 0    timestamp: 1351994
<info> time_sync: 696, 540798, 0    timestamp: 1351995
<info> time_sync: 16744, 540798, 0    timestamp: 1351996
<info> time_sync: 32792, 540798, 0    timestamp: 1351997
<info> time_sync: 8656, 540799, 0    timestamp: 1351998
<info> time_sync: 24657, 540799, 0    timestamp: 1351999
<info> time_sync: 656, 540800, 0    timestamp: 1352000
<info> time_sync: 32656, 540802, 0    timestamp: 1352007
<info> time_sync: 8656, 540803, 0    timestamp: 1352008
<info> time_sync: 24656, 540803, 0    timestamp: 1352009
<info> time_sync: 656, 540804, 0    timestamp: 1352010
<info> time_sync: 16656, 540804, 0    timestamp: 1352011
<info> time_sync: 32656, 540804, 0    timestamp: 1352012
<info> time_sync: 8656, 540805, 0    timestamp: 1352013
<info> time_sync: 24656, 540805, 0    timestamp: 1352014
<info> time_sync: 656, 540806, 0    timestamp: 1352015
<info> time_sync: 16656, 540806, 0    timestamp: 1352016
<info> time_sync: 32656, 540806, 0    timestamp: 1352017
<info> time_sync: 8656, 540807, 0    timestamp: 1352018
<info> time_sync: 24656, 540807, 0    timestamp: 1352019
<info> time_sync: 656, 540808, 0    timestamp: 1352020
<info> time_sync: 16657, 540808, 0    timestamp: 1352021
<info> time_sync: 32656, 540808, 0    timestamp: 1352022
<info> time_sync: 8655, 540809, 0    timestamp: 1352023
<info> time_sync: 24656, 540809, 0    timestamp: 1352024
<info> time_sync: 657, 540810, 0    timestamp: 1352025
<info> time_sync: 16656, 540810, 0    timestamp: 1352026
<info> time_sync: 32656, 540810, 0    timestamp: 1352027
<info> time_sync: 24657, 540811, 0    timestamp: 1352029
<info> time_sync: 647, 540812, 0    timestamp: 1352030
<info> time_sync: 16657, 540812, 0    timestamp: 1352031
<info> app: diff: 40
<info> time_sync: 37366, 540812, 0    timestamp: 1352032
<info> time_sync: 8654, 540813, 0    timestamp: 1352033
<info> time_sync: 24819, 540813, 0    timestamp: 1352034
<info> time_sync: 800, 540814, 0    timestamp: 1352035
<info> time_sync: 16801, 540814, 0    timestamp: 1352036
<info> time_sync: 8656, 540817, 0    timestamp: 1352043
<info> time_sync: 24656, 540817, 0    timestamp: 1352044
<info> time_sync: 656, 540818, 0    timestamp: 1352045
<info> time_sync: 16656, 540818, 0    timestamp: 1352046
<info> time_sync: 32656, 540818, 0    timestamp: 1352047
<info> time_sync: 8656, 540819, 0    timestamp: 1352048
<info> time_sync: 24656, 540819, 0    timestamp: 1352049
<info> time_sync: 656, 540820, 0    timestamp: 1352050
<info> time_sync: 16656, 540820, 0    timestamp: 1352051
<info> time_sync: 32656, 540820, 0    timestamp: 1352052
<info> time_sync: 8656, 540821, 0    timestamp: 1352053
<info> time_sync: 24656, 540821, 0    timestamp: 1352054
<info> time_sync: 656, 540822, 0    timestamp: 1352055
<info> time_sync: 16655, 540822, 0    timestamp: 1352056
<info> time_sync: 32656, 540822, 0    timestamp: 1352057
<info> time_sync: 8655, 540823, 0    timestamp: 1352058
<info> time_sync: 24656, 540823, 0    timestamp: 1352059
<info> time_sync: 657, 540824, 0    timestamp: 1352060
<info> time_sync: 16647, 540824, 0    timestamp: 1352061
<info> time_sync: 32656, 540824, 0    timestamp: 1352062
<info> time_sync: 8656, 540825, 0    timestamp: 1352063
<info> time_sync: 657, 540826, 0    timestamp: 1352065
<info> time_sync: 16647, 540826, 0    timestamp: 1352066
<info> time_sync: 32647, 540826, 0    timestamp: 1352067
<info> time_sync: 8656, 540827, 0    timestamp: 1352068
<info> time_sync: 24656, 540827, 0    timestamp: 1352069
<info> time_sync: 656, 540828, 0    timestamp: 1352070
<info> time_sync: 16656, 540828, 0    timestamp: 1352071
<info> time_sync: 35509, 540828, 0    timestamp: 1352072
<info> app: diff: 40
<info> time_sync: 8699, 540829, 0    timestamp: 1352073
<info> time_sync: 24663, 540829, 0    timestamp: 1352074
<info> time_sync: 737, 540830, 0    timestamp: 1352075
<info> time_sync: 16649, 540830, 0    timestamp: 1352076
<info> time_sync: 32648, 540830, 0    timestamp: 1352077
<info> time_sync: 8648, 540831, 0    timestamp: 1352078
<info> time_sync: 657, 540832, 0    timestamp: 1352080
<info> time_sync: 16647, 540832, 0    timestamp: 1352081
<info> time_sync: 32657, 540832, 0    timestamp: 1352082
<info> time_sync: 8656, 540833, 0    timestamp: 1352083
<info> time_sync: 16656, 540836, 0    timestamp: 1352091
<info> time_sync: 32656, 540836, 0    timestamp: 1352092
<info> time_sync: 8656, 540837, 0    timestamp: 1352093
<info> time_sync: 24656, 540837, 0    timestamp: 1352094
<info> time_sync: 656, 540838, 0    timestamp: 1352095
<info> time_sync: 16656, 540838, 0    timestamp: 1352096
<info> time_sync: 32656, 540838, 0    timestamp: 1352097
<info> time_sync: 8656, 540839, 0    timestamp: 1352098
<info> time_sync: 24656, 540839, 0    timestamp: 1352099
<info> time_sync: 656, 540840, 0    timestamp: 1352100
<info> time_sync: 16656, 540840, 0    timestamp: 1352101
<info> time_sync: 32656, 540840, 0    timestamp: 1352102
<info> time_sync: 8656, 540841, 0    timestamp: 1352103
<info> time_sync: 24656, 540841, 0    timestamp: 1352104
<info> time_sync: 656, 540842, 0    timestamp: 1352105
<info> time_sync: 16656, 540842, 0    timestamp: 1352106
<info> time_sync: 32656, 540842, 0    timestamp: 1352107
<info> time_sync: 8657, 540843, 0    timestamp: 1352108
<info> time_sync: 24656, 540843, 0    timestamp: 1352109
<info> time_sync: 656, 540844, 0    timestamp: 1352110
<info> time_sync: 16656, 540844, 0    timestamp: 1352111
<info> app: diff: 40
<info> time_sync: 37632, 540844, 0    timestamp: 1352112
<info> time_sync: 8654, 540845, 0    timestamp: 1352113
<info> time_sync: 24681, 540845, 0    timestamp: 1352114
<info> time_sync: 644, 540846, 0    timestamp: 1352115
<info> time_sync: 16680, 540846, 0    timestamp: 1352116
<info> time_sync: 32728, 540846, 0    timestamp: 1352117
<info> time_sync: 8656, 540847, 0    timestamp: 1352118
<info> time_sync: 24657, 540847, 0    timestamp: 1352119
<info> time_sync: 8656, 540851, 0    timestamp: 1352128
<info> time_sync: 24656, 540851, 0    timestamp: 1352129
<info> time_sync: 656, 540852, 0    timestamp: 1352130
<info> time_sync: 16656, 540852, 0    timestamp: 1352131
<info> time_sync: 32656, 540852, 0    timestamp: 1352132
<info> time_sync: 8656, 540853, 0    timestamp: 1352133
<info> time_sync: 24656, 540853, 0    timestamp: 1352134
<info> time_sync: 656, 540854, 0    timestamp: 1352135
<info> time_sync: 16656, 540854, 0    timestamp: 1352136
<info> time_sync: 32656, 540854, 0    timestamp: 1352137
<info> time_sync: 8656, 540855, 0    timestamp: 1352138
<info> time_sync: 24656, 540855, 0    timestamp: 1352139
<info> time_sync: 656, 540856, 0    timestamp: 1352140
<info> time_sync: 16656, 540856, 0    timestamp: 1352141
<info> time_sync: 32656, 540856, 0    timestamp: 1352142
<info> time_sync: 8656, 540857, 0    timestamp: 1352143
<info> time_sync: 24656, 540857, 0    timestamp: 1352144
<info> time_sync: 656, 540858, 0    timestamp: 1352145
<info> time_sync: 16657, 540858, 0    timestamp: 1352146
<info> time_sync: 32647, 540858, 0    timestamp: 1352147
<info> time_sync: 8656, 540859, 0    timestamp: 1352148
<info> time_sync: 24656, 540859, 0    timestamp: 1352149
<info> time_sync: 656, 540860, 0    timestamp: 1352150
<info> time_sync: 16657, 540860, 0    timestamp: 1352151
<info> app: diff: 40
<info> time_sync: 37414, 540860, 0    timestamp: 1352152
<info> time_sync: 8775, 540861, 0    timestamp: 1352153
<info> time_sync: 24839, 540861, 0    timestamp: 1352154
<info> time_sync: 644, 540862, 0    timestamp: 1352155
<info> time_sync: 16718, 540862, 0    timestamp: 1352156
<info> time_sync: 32719, 540862, 0    timestamp: 1352157
<info> time_sync: 656, 540866, 0    timestamp: 1352165
<info> time_sync: 16656, 540866, 0    timestamp: 1352166
<info> time_sync: 32656, 540866, 0    timestamp: 1352167
<info> time_sync: 8656, 540867, 0    timestamp: 1352168
<info> time_sync: 24656, 540867, 0    timestamp: 1352169
<info> time_sync: 656, 540868, 0    timestamp: 1352170
<info> time_sync: 16656, 540868, 0    timestamp: 1352171
<info> time_sync: 32656, 540868, 0    timestamp: 1352172
<info> time_sync: 8656, 540869, 0    timestamp: 1352173
<info> time_sync: 24656, 540869, 0    timestamp: 1352174
<info> time_sync: 656, 540870, 0    timestamp: 1352175
<info> time_sync: 16656, 540870, 0    timestamp: 1352176
<info> time_sync: 32656, 540870, 0    timestamp: 1352177
<info> time_sync: 8656, 540871, 0    timestamp: 1352178
<info> time_sync: 24656, 540871, 0    timestamp: 1352179
<info> time_sync: 656, 540872, 0    timestamp: 1352180
<info> time_sync: 16656, 540872, 0    timestamp: 1352181
<info> time_sync: 32656, 540872, 0    timestamp: 1352182
<info> time_sync: 8657, 540873, 0    timestamp: 1352183
<info> time_sync: 24647, 540873, 0    timestamp: 1352184
<info> time_sync: 656, 540874, 0    timestamp: 1352185
<info> time_sync: 16655, 540874, 0    timestamp: 1352186
<info> time_sync: 32656, 540874, 0    timestamp: 1352187
<info> time_sync: 8657, 540875, 0    timestamp: 1352188
<info> time_sync: 24656, 540875, 0    timestamp: 1352189
<info> time_sync: 656, 540876, 0    timestamp: 1352190
<info> time_sync: 16657, 540876, 0    timestamp: 1352191
<info> app: diff: 40
<info> time_sync: 37701, 540876, 0    timestamp: 1352192
<info> time_sync: 8743, 540877, 0    timestamp: 1352193
<info> time_sync: 24807, 540877, 0    timestamp: 1352194
<info> time_sync: 644, 540878, 0    timestamp: 1352195
<info> time_sync: 16705, 540878, 0    timestamp: 1352196
<info> time_sync: 32704, 540878, 0    timestamp: 1352197
<info> time_sync: 16656, 540882, 0    timestamp: 1352206
<info> time_sync: 32656, 540882, 0    timestamp: 1352207
<info> time_sync: 8656, 540883, 0    timestamp: 1352208
<info> time_sync: 24656, 540883, 0    timestamp: 1352209
<info> time_sync: 656, 540884, 0    timestamp: 1352210
<info> time_sync: 16656, 540884, 0    timestamp: 1352211
<info> time_sync: 32656, 540884, 0    timestamp: 1352212
<info> time_sync: 8656, 540885, 0    timestamp: 1352213
<info> time_sync: 24656, 540885, 0    timestamp: 1352214
<info> time_sync: 656, 540886, 0    timestamp: 1352215
<info> time_sync: 16656, 540886, 0    timestamp: 1352216
<info> time_sync: 32656, 540886, 0    timestamp: 1352217
<info> time_sync: 8655, 540887, 0    timestamp: 1352218
<info> time_sync: 24656, 540887, 0    timestamp: 1352219
<info> time_sync: 655, 540888, 0    timestamp: 1352220
<info> time_sync: 16656, 540888, 0    timestamp: 1352221
<info> time_sync: 32656, 540888, 0    timestamp: 1352222
<info> time_sync: 8656, 540889, 0    timestamp: 1352223
<info> time_sync: 24656, 540889, 0    timestamp: 1352224
<info> time_sync: 656, 540890, 0    timestamp: 1352225
<info> time_sync: 16656, 540890, 0    timestamp: 1352226
<info> time_sync: 32657, 540890, 0    timestamp: 1352227
<info> time_sync: 8647, 540891, 0    timestamp: 1352228
<info> time_sync: 24656, 540891, 0    timestamp: 1352229
<info> time_sync: 656, 540892, 0    timestamp: 1352230
<info> time_sync: 16657, 540892, 0    timestamp: 1352231
<info> time_sync: 35557, 540892, 0    timestamp: 1352232
<info> app: diff: 40
<info> time_sync: 8747, 540893, 0    timestamp: 1352233
<info> time_sync: 24711, 540893, 0    timestamp: 1352234
<info> time_sync: 792, 540894, 0    timestamp: 1352235
<info> time_sync: 16744, 540894, 0    timestamp: 1352236
<info> time_sync: 32792, 540894, 0    timestamp: 1352237
<info> time_sync: 8651, 540895, 0    timestamp: 1352238
<info> time_sync: 16656, 540898, 0    timestamp: 1352246
<info> time_sync: 32656, 540898, 0    timestamp: 1352247
<info> time_sync: 8656, 540899, 0    timestamp: 1352248
<info> time_sync: 24656, 540899, 0    timestamp: 1352249
<info> time_sync: 656, 540900, 0    timestamp: 1352250
<info> time_sync: 16655, 540900, 0    timestamp: 1352251
<info> time_sync: 32656, 540900, 0    timestamp: 1352252
<info> time_sync: 8655, 540901, 0    timestamp: 1352253
<info> time_sync: 24656, 540901, 0    timestamp: 1352254
<info> time_sync: 656, 540902, 0    timestamp: 1352255
<info> time_sync: 16656, 540902, 0    timestamp: 1352256
<info> time_sync: 32656, 540902, 0    timestamp: 1352257
<info> time_sync: 8656, 540903, 0    timestamp: 1352258
<info> time_sync: 24656, 540903, 0    timestamp: 1352259
<info> time_sync: 656, 540904, 0    timestamp: 1352260
<info> time_sync: 16656, 540904, 0    timestamp: 1352261
<info> time_sync: 32656, 540904, 0    timestamp: 1352262
<info> time_sync: 8656, 540905, 0    timestamp: 1352263
<info> time_sync: 24657, 540905, 0    timestamp: 1352264
<info> time_sync: 647, 540906, 0    timestamp: 1352265
<info> time_sync: 16656, 540906, 0    timestamp: 1352266
<info> time_sync: 32656, 540906, 0    timestamp: 1352267
<info> time_sync: 24657, 540907, 0    timestamp: 1352269
<info> time_sync: 647, 540908, 0    timestamp: 1352270
<info> time_sync: 16657, 540908, 0    timestamp: 1352271
<info> app: diff: 40
<info> time_sync: 37433, 540908, 0    timestamp: 1352272
<info> time_sync: 8690, 540909, 0    timestamp: 1352273
<info> time_sync: 24835, 540909, 0    timestamp: 1352274
<info> time_sync: 816, 540910, 0    timestamp: 1352275
<info> time_sync: 16817, 540910, 0    timestamp: 1352276
<info> time_sync: 8655, 540913, 0    timestamp: 1352283
<info> time_sync: 24656, 540913, 0    timestamp: 1352284
<info> time_sync: 655, 540914, 0    timestamp: 1352285
<info> time_sync: 16656, 540914, 0    timestamp: 1352286
<info> time_sync: 32656, 540914, 0    timestamp: 1352287
<info> time_sync: 8656, 540915, 0    timestamp: 1352288
<info> time_sync: 24656, 540915, 0    timestamp: 1352289
<info> time_sync: 656, 540916, 0    timestamp: 1352290
<info> time_sync: 16656, 540916, 0    timestamp: 1352291
<info> time_sync: 32656, 540916, 0    timestamp: 1352292
<info> time_sync: 8656, 540917, 0    timestamp: 1352293
<info> time_sync: 24656, 540917, 0    timestamp: 1352294
<info> time_sync: 656, 540918, 0    timestamp: 1352295
<info> time_sync: 16656, 540918, 0    timestamp: 1352296
<info> time_sync: 32657, 540918, 0    timestamp: 1352297
<info> time_sync: 8647, 540919, 0    timestamp: 1352298
<info> time_sync: 24656, 540919, 0    timestamp: 1352299
<info> time_sync: 656, 540920, 0    timestamp: 1352300
<info> time_sync: 32657, 540920, 0    timestamp: 1352302
<info> time_sync: 8647, 540921, 0    timestamp: 1352303
<info> time_sync: 24647, 540921, 0    timestamp: 1352304
<info> time_sync: 656, 540922, 0    timestamp: 1352305
<info> time_sync: 16656, 540922, 0    timestamp: 1352306
<info> time_sync: 32656, 540922, 0    timestamp: 1352307
<info> time_sync: 8656, 540923, 0    timestamp: 1352308
<info> time_sync: 24657, 540923, 0    timestamp: 1352309
<info> time_sync: 647, 540924, 0    timestamp: 1352310
<info> time_sync: 16656, 540924, 0    timestamp: 1352311
<info> app: diff: 40
<info> time_sync: 37760, 540924, 0    timestamp: 1352312
<info> time_sync: 8736, 540925, 0    timestamp: 1352313
<info> time_sync: 24845, 540925, 0    timestamp: 1352314
<info> time_sync: 792, 540926, 0    timestamp: 1352315
<info> time_sync: 32644, 540926, 0    timestamp: 1352317
<info> time_sync: 8650, 540927, 0    timestamp: 1352318
<info> time_sync: 24642, 540927, 0    timestamp: 1352319
<info> time_sync: 646, 540928, 0    timestamp: 1352320
<info> time_sync: 16643, 540928, 0    timestamp: 1352321
<info> time_sync: 32656, 540928, 0    timestamp: 1352322
<info> time_sync: 8657, 540929, 0    timestamp: 1352323
<info> time_sync: 24647, 540929, 0    timestamp: 1352324
<info> time_sync: 32656, 540932, 0    timestamp: 1352332
<info> time_sync: 8656, 540933, 0    timestamp: 1352333
<info> time_sync: 24656, 540933, 0    timestamp: 1352334
<info> time_sync: 656, 540934, 0    timestamp: 1352335
<info> time_sync: 16656, 540934, 0    timestamp: 1352336
<info> time_sync: 32656, 540934, 0    timestamp: 1352337
<info> time_sync: 8656, 540935, 0    timestamp: 1352338
<info> time_sync: 24656, 540935, 0    timestamp: 1352339
<info> time_sync: 656, 540936, 0    timestamp: 1352340
<info> time_sync: 16656, 540936, 0    timestamp: 1352341
<info> time_sync: 32656, 540936, 0    timestamp: 1352342
<info> time_sync: 8656, 540937, 0    timestamp: 1352343
<info> time_sync: 24656, 540937, 0    timestamp: 1352344
<info> time_sync: 656, 540938, 0    timestamp: 1352345
<info> time_sync: 16656, 540938, 0    timestamp: 1352346
<info> time_sync: 32656, 540938, 0    timestamp: 1352347
<info> time_sync: 8656, 540939, 0    timestamp: 1352348
<info> time_sync: 24657, 540939, 0    timestamp: 1352349
<info> time_sync: 656, 540940, 0    timestamp: 1352350
<info> time_sync: 16656, 540940, 0    timestamp: 1352351
<info> app: diff: 40
<info> time_sync: 37467, 540940, 0    timestamp: 1352352
<info> time_sync: 8723, 540941, 0    timestamp: 1352353
<info> time_sync: 24813, 540941, 0    timestamp: 1352354
<info> time_sync: 760, 540942, 0    timestamp: 1352355
<info> time_sync: 16808, 540942, 0    timestamp: 1352356
<info> time_sync: 32644, 540942, 0    timestamp: 1352357
<info> time_sync: 8656, 540943, 0    timestamp: 1352358
<info> time_sync: 24657, 540943, 0    timestamp: 1352359
<info> time_sync: 652, 540944, 0    timestamp: 1352360
<info> time_sync: 8656, 540947, 0    timestamp: 1352368
<info> time_sync: 24656, 540947, 0    timestamp: 1352369
<info> time_sync: 656, 540948, 0    timestamp: 1352370
<info> time_sync: 16656, 540948, 0    timestamp: 1352371
<info> time_sync: 32656, 540948, 0    timestamp: 1352372
<info> time_sync: 8656, 540949, 0    timestamp: 1352373
<info> time_sync: 24656, 540949, 0    timestamp: 1352374
<info> time_sync: 656, 540950, 0    timestamp: 1352375
<info> time_sync: 16656, 540950, 0    timestamp: 1352376
<info> time_sync: 32656, 540950, 0    timestamp: 1352377
<info> time_sync: 8656, 540951, 0    timestamp: 1352378
<info> time_sync: 24656, 540951, 0    timestamp: 1352379
<info> time_sync: 656, 540952, 0    timestamp: 1352380
<info> time_sync: 16655, 540952, 0    timestamp: 1352381
<info> time_sync: 32656, 540952, 0    timestamp: 1352382
<info> time_sync: 8655, 540953, 0    timestamp: 1352383
<info> time_sync: 24656, 540953, 0    timestamp: 1352384
<info> time_sync: 657, 540954, 0    timestamp: 1352385
<info> time_sync: 16656, 540954, 0    timestamp: 1352386
<info> time_sync: 32656, 540954, 0    timestamp: 1352387
<info> time_sync: 8656, 540955, 0    timestamp: 1352388
<info> time_sync: 24656, 540955, 0    timestamp: 1352389
<info> time_sync: 657, 540956, 0    timestamp: 1352390
<info> time_sync: 16657, 540956, 0    timestamp: 1352391
<info> app: diff: 40
<error> app: ERROR 0 [NRF_SUCCESS] ...

--------------------------------------------------------------

I ran my tests multiple times. It looks like that the offset always occures when the sync_timer_val goes from 40000 to 0. Sometimes I also saw a bit of "jumping" of the sync_timer_val. This is the debug log of the peripheral of another test run:

[00:07:02.453,063] <info> time_sync: 39724, 3, 174194    timestamp: 435495
[00:07:02.493,041] <info> time_sync: 39729, 6, 174207    timestamp: 435535
[00:07:02.533,081] <info> time_sync: 39730, 22, 174207    timestamp: 435575
[00:07:02.573,120] <info> time_sync: 101, 0, 174246    timestamp: 435615
[00:07:02.613,098] <info> time_sync: 39747, 2, 174259    timestamp: 435655
[00:07:02.653,076] <info> time_sync: 39752, 5, 174272    timestamp: 435695
[00:07:02.693,054] <info> time_sync: 39756, 8, 174285    timestamp: 435735
[00:07:02.733,093] <info> time_sync: 39757, 24, 174285    timestamp: 435775
[00:07:02.773,071] <info> time_sync: 39770, 1, 174324    timestamp: 435815
[00:07:02.813,110] <info> time_sync: 39775, 4, 174337    timestamp: 435855
[00:07:02.853,088] <info> time_sync: 39779, 7, 174350    timestamp: 435895
[00:07:02.893,066] <info> time_sync: 39780, 23, 174350    timestamp: 435935
[00:07:02.933,105] <info> time_sync: 39793, 0, 174389    timestamp: 435975
[00:07:02.973,083] <info> time_sync: 39798, 3, 174402    timestamp: 436015
[00:07:03.013,122] <info> time_sync: 39802, 6, 174415    timestamp: 436055
[00:07:03.053,100] <info> time_sync: 39803, 22, 174415    timestamp: 436095
[00:07:03.093,139] <info> time_sync: 102, 0, 174454    timestamp: 436135
[00:07:03.133,117] <info> time_sync: 39820, 2, 174467    timestamp: 436175
[00:07:03.173,095] <info> time_sync: 39825, 5, 174480    timestamp: 436215
[00:07:03.213,134] <info> time_sync: 39829, 8, 174493    timestamp: 436255
[00:07:03.253,112] <info> time_sync: 39830, 24, 174493    timestamp: 436295
[00:07:03.293,090] <info> time_sync: 39843, 1, 174532    timestamp: 436335
[00:07:03.333,129] <info> time_sync: 39848, 4, 174545    timestamp: 436375
[00:07:03.373,107] <info> time_sync: 39853, 7, 174558    timestamp: 436415
[00:07:03.413,085] <info> time_sync: 39854, 23, 174558    timestamp: 436455
[00:07:03.453,125] <info> time_sync: 39866, 0, 174597    timestamp: 436495
[00:07:03.493,103] <info> time_sync: 39871, 3, 174610    timestamp: 436535
[00:07:03.533,142] <info> time_sync: 39875, 6, 174623    timestamp: 436575
[00:07:03.573,120] <info> time_sync: 39876, 22, 174623    timestamp: 436615
[00:07:03.613,159] <info> time_sync: 100, 0, 174662    timestamp: 436655
[00:07:03.653,137] <info> time_sync: 39894, 2, 174675    timestamp: 436695
[00:07:03.693,115] <info> time_sync: 39898, 5, 174688    timestamp: 436735
[00:07:03.733,154] <info> time_sync: 39903, 8, 174701    timestamp: 436775
[00:07:03.773,132] <info> time_sync: 39904, 24, 174701    timestamp: 436815
[00:07:03.813,110] <info> time_sync: 39916, 1, 174740    timestamp: 436855
[00:07:03.853,149] <info> time_sync: 39921, 4, 174753    timestamp: 436895
[00:07:03.893,127] <info> time_sync: 39926, 7, 174766    timestamp: 436935
[00:07:03.933,166] <info> time_sync: 39927, 23, 174766    timestamp: 436975
[00:07:03.973,144] <info> time_sync: 39939, 0, 174805    timestamp: 437015
[00:07:04.013,122] <info> time_sync: 39944, 3, 174818    timestamp: 437055
[00:07:04.053,161] <info> time_sync: 39948, 6, 174831    timestamp: 437095
[00:07:04.093,139] <info> time_sync: 39949, 22, 174831    timestamp: 437135
[00:07:04.133,178] <info> time_sync: 102, 0, 174870    timestamp: 437175
[00:07:04.173,156] <info> time_sync: 39967, 2, 174883    timestamp: 437215
[00:07:04.213,134] <info> time_sync: 39971, 5, 174896    timestamp: 437255
[00:07:04.253,173] <info> time_sync: 39976, 8, 174909    timestamp: 437295
[00:07:04.293,151] <info> time_sync: 39977, 24, 174909    timestamp: 437335
[00:07:04.333,129] <info> time_sync: 39990, 1, 174948    timestamp: 437375
[00:07:04.373,168] <info> time_sync: 39994, 4, 174961    timestamp: 437415
[00:07:04.413,146] <info> time_sync: 39999, 7, 174974    timestamp: 437455
[00:07:04.453,186] <info> time_sync: 0, 23, 174974    timestamp: 437493

--------------------------------------------------------------

Finally I want to point something out regarding the priority.

Audun said:
Either way, since you are calling the timestamp function from a lower priority that SWI3_EGU3_IRQHandler

This is not fully correct. I would like to call the timestamp function from the same priority than the SWI3_EGU3_IRQHandler (If this is possible?). The timestamp function gets called with priority 6. In order to match this line in your timers_capture() function:

APP_ERROR_CHECK_BOOL(current_int_priority_get() > TIME_SYNC_EVT_HANDLER_IRQ_PRIORITY);

I have to set TIME_SYNC_EVT_HANDLER_IRQ_PRIORITY at least to 5. Which could cause an unwanted behaviour. Is it possible to call it from the same priority?

Another consequence of this APP_ERROR_CHECK_BOOL(...) line is, that I have to use

#define TIME_SYNC_TX_OFFSET_REALIGN_TIMEOUT 0

because every other value would cause an error with this function:

static int32_t calculate_tx_start_offset(void)

--------------------------------------------------------------

So I am still having the abrupt offset issue.

Do you have any other suggestions on how to solve this issue. We highly appreciate your help with our problem. It still looks like that the success of our project depends on your help.

Thank you very much in advance.

Best regards,

Michael

0 Audun over 4 years ago

Hi Michael,

Michael01101 said:
So I am still having the abrupt offset issue.

Do you have any other suggestions on how to solve this issue. We highly appreciate your help with our problem. It still looks like that the success of our project depends on your help.

Thanks for the update. I have spent time in the office today to set up a better test case to reproduce the issue you see:

On the receiver side I have a RTC set up to capture a timestamp every X ms, and I look at the relative difference between the current and previous timestamp to determine if this is a sane value. I think this is functionally equivalent of the setup you have?

I believe I see the issue, and will work on confirming my setup and work on a solution.

Best regards,

Audun
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0 Michael01101 over 4 years ago in reply to Audun

Hello Audun,

thank you very much for the reply and the effort you put into this.

Basically this is a functionally equivalent of my setup. But one thing is different:

On the receiver side of the sync beacons (peripheral) I have a TIMER (TIMER peripheral) to capture a timestamp every 40ms. Then I check the difference between the current and the previous timestamp, as you already mentioned. If the difference is higher than 41 or lower than 39 I generate an error.

If you are interested, this is the configuration of the TIMER:

static const nrfx_timer_t               m_timer = NRFX_TIMER_INSTANCE(1);

void saadc_sampling_event_init(void)
{
    ret_code_t err_code;
    err_code = nrf_drv_ppi_init();
    APP_ERROR_CHECK(err_code);
    
    nrfx_timer_config_t timer_config = NRFX_TIMER_DEFAULT_CONFIG;
    timer_config.frequency = NRF_TIMER_FREQ_16MHz;
    err_code = nrfx_timer_init(&m_timer, &timer_config, timer_handler);
    APP_ERROR_CHECK(err_code);

    /* setup m_timer for compare event */
    uint32_t ticks = nrfx_timer_ms_to_ticks(&m_timer,1);
    nrfx_timer_extended_compare(&m_timer, NRF_TIMER_CC_CHANNEL0, ticks, NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, false);
    nrfx_timer_enable(&m_timer);

    uint32_t timer_compare_event_addr = nrfx_timer_compare_event_address_get(&m_timer, NRF_TIMER_CC_CHANNEL0);
    uint32_t saadc_sample_event_addr = nrfx_saadc_sample_task_get();

    /* setup ppi channel so that timer compare event is triggering sample task in SAADC */
    err_code = nrf_drv_ppi_channel_alloc(&m_ppi_channel);
    APP_ERROR_CHECK(err_code);
    
    err_code = nrf_drv_ppi_channel_assign(m_ppi_channel, timer_compare_event_addr, saadc_sample_event_addr);
    APP_ERROR_CHECK(err_code);
}

I setup a ppi channel so that timer compare event is triggering sample task in SAADC (every 1ms). In the saadc_callback I call my timestamp function every 40th time (every 40ms) .

Audun said:
I believe I see the issue, and will work on confirming my setup and work on a solution.

That sounds great. I am looking forward to hearing from you.

Please let me know, if you need anything more.

Thank you very much in advance.

Best regards,

Michael

0 Audun over 4 years ago in reply to Michael01101

Hi Michael,

can you try to replace your timers_capture function again with the one below? This should have no restrictions on what interrupt level it can be called from. It won't have a potentially long delay either.

With this change I haven't seen the issue again on my side. Will let my test case run over the weekend and see if any issues are triggered.

I've not looked closely at the TIMER reference code you posted, but will take a closer look at that if the issue persists on your side.

Best regards,

Audun

static void timers_capture(uint32_t * p_sync_timer_val, uint32_t * p_count_timer_val, uint32_t * p_peer_counter)
{
    static nrf_atomic_flag_t m_timestamp_capture_flag = 0;

    nrf_atomic_u32_t peer_counter;

    if (nrf_atomic_flag_set_fetch(&m_timestamp_capture_flag) != 0)
    {
        // Not thread-safe
        APP_ERROR_CHECK_BOOL(false);
    }

    nrf_ppi_channel_t ppi_chn;
    nrfx_err_t ret = nrfx_ppi_channel_alloc(&ppi_chn);
    APP_ERROR_CHECK_BOOL(ret == NRFX_SUCCESS);

    ppi_counter_timer_capture_configure(ppi_chn);

    NVIC_DisableIRQ(m_params.egu_irq_type);

    bool counter_adjustment_triggered;

    // Loop while there is a chance of capturing during timer adjustment,
    // or if timer wraparound happens very close to the same clock cycle as the capture.
    do
    {
        counter_adjustment_triggered = m_params.egu->EVENTS_TRIGGERED[0];

        m_params.egu->TASKS_TRIGGER[1] = 1;

        if (counter_adjustment_triggered)
        {
            peer_counter = ((sync_pkt_t *) mp_curr_adj_pkt)->counter_val;
        }
        else
        {
            peer_counter = m_master_counter;
        }
    } while (counter_adjustment_triggered != m_params.egu->EVENTS_TRIGGERED[0] ||
             m_params.high_freq_timer[0]->CC[3] < 2);

    NVIC_EnableIRQ(m_params.egu_irq_type);

    ppi_counter_timer_capture_disable(ppi_chn);
    nrfx_ppi_channel_free(ppi_chn);

    *p_sync_timer_val  = m_params.high_freq_timer[0]->CC[3];
    *p_count_timer_val = (m_params.high_freq_timer[1]->CC[0]);
    *p_peer_counter    = peer_counter;

    nrf_atomic_flag_clear(&m_timestamp_capture_flag);
}

0 Audun over 4 years ago in reply to Audun

Hi again Michael,

there were some corner cases that triggered during the weekend, and I've made some further refinements to the code now. Can you try the following on your side?

static void timers_capture(uint32_t * p_sync_timer_val, uint32_t * p_count_timer_val, uint32_t * p_peer_counter)
{
    static nrf_atomic_flag_t m_timestamp_capture_flag = 0;

    nrf_atomic_u32_t peer_counter;

    if (nrf_atomic_flag_set_fetch(&m_timestamp_capture_flag) != 0)
    {
        // Not thread-safe
        APP_ERROR_CHECK_BOOL(false);
    }

    nrf_ppi_channel_t ppi_chn;
    nrfx_err_t ret = nrfx_ppi_channel_alloc(&ppi_chn);
    APP_ERROR_CHECK_BOOL(ret == NRFX_SUCCESS);

    ppi_counter_timer_capture_configure(ppi_chn);

    NVIC_DisableIRQ(m_params.egu_irq_type);

    bool counter_adjustment_triggered;

    // Loop if adjustment procedure happened close to timer capture
    do
    {
        counter_adjustment_triggered = m_params.egu->EVENTS_TRIGGERED[0];

        m_params.egu->EVENTS_TRIGGERED[1] = 0;
        m_params.egu->TASKS_TRIGGER[1] = 1;
        while (m_params.egu->EVENTS_TRIGGERED[1] == 0)
        {
            __NOP();
        }

        if (m_params.high_freq_timer[1]->CC[0] < 2 || m_params.high_freq_timer[0]->CC[3] < 2)
        {
            /* Capture again if capture happened too close to adjustment or wraparound */
            m_params.egu->EVENTS_TRIGGERED[1] = 0;
            m_params.egu->TASKS_TRIGGER[1] = 1;
            while (m_params.egu->EVENTS_TRIGGERED[1] == 0)
            {
                __NOP();
            }
        }

        if (counter_adjustment_triggered)
        {
            peer_counter = ((sync_pkt_t *) mp_curr_adj_pkt)->counter_val;
        }
        else
        {
            peer_counter = m_master_counter;
        }
    } while (counter_adjustment_triggered != m_params.egu->EVENTS_TRIGGERED[0] ||
             m_params.high_freq_timer[0]->CC[3] < 2);

    NVIC_EnableIRQ(m_params.egu_irq_type);

    ppi_counter_timer_capture_disable(ppi_chn);
    nrfx_ppi_channel_free(ppi_chn);

    *p_sync_timer_val  = m_params.high_freq_timer[0]->CC[3];
    *p_count_timer_val = (m_params.high_freq_timer[1]->CC[0]);
    *p_peer_counter    = peer_counter;

    nrf_atomic_flag_clear(&m_timestamp_capture_flag);
}