nrf52840 DK scanning issue

Question

Hi All,

I have the strange issue with scanning. I have the project losely based on examples where I created peripheral adevrtising with 1s interval. This sends the custom adv packet with counter value. The issue is that central one stops receiving after a random while and then resumes or not after long while. Trying to solve it changed scanning timeout from 0 to 3000 and when it times out start scan again. The debug terminal shows that sometimes after scan start nothing is received at all - I filter it to one peripheral only.

<info> app: RSSI = -54 (dBm), Counter =  1658
<info> app: RSSI = -51 (dBm), Counter =  1659
<info> app: RSSI = -49 (dBm), Counter =  1660
<info> app: RSSI = -47 (dBm), Counter =  1661
<info> app: RSSI = -47 (dBm), Counter =  1662
<info> app: RSSI = -47 (dBm), Counter =  1663
<info> app: RSSI = -48 (dBm), Counter =  1665
<info> app: RSSI = -48 (dBm), Counter =  1668
<info> app: RSSI = -47 (dBm), Counter =  1669
<info> app: RSSI = -49 (dBm), Counter =  1670
<info> app: RSSI = -48 (dBm), Counter =  1671
<info> app: RSSI = -48 (dBm), Counter =  1672
<info> app: RSSI = -49 (dBm), Counter =  1673
<info> app: RSSI = -48 (dBm), Counter =  1674
<info> app: RSSI = -47 (dBm), Counter =  1675
<info> app: RSSI = -47 (dBm), Counter =  1676
<info> app: RSSI = -47 (dBm), Counter =  1677
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -51 (dBm), Counter =  1698
<info> app: RSSI = -50 (dBm), Counter =  1699
<info> app: RSSI = -51 (dBm), Counter =  1700
<info> app: RSSI = -51 (dBm), Counter =  1701
<info> app: RSSI = -51 (dBm), Counter =  1702
<info> app: RSSI = -51 (dBm), Counter =  1703
<info> app: RSSI = -51 (dBm), Counter =  1704
<info> app: RSSI = -50 (dBm), Counter =  1705
<info> app: RSSI = -52 (dBm), Counter =  1706
<info> app: RSSI = -51 (dBm), Counter =  1707
<info> app: RSSI = -53 (dBm), Counter =  1708
<info> app: RSSI = -57 (dBm), Counter =  1709
<info> app: RSSI = -51 (dBm), Counter =  1710
<info> app: RSSI = -51 (dBm), Counter =  1711
<info> app: RSSI = -51 (dBm), Counter =  1712
<info> app: RSSI = -54 (dBm), Counter =  1713
<info> app: RSSI = -52 (dBm), Counter =  1715
<info> app: RSSI = -51 (dBm), Counter =  1717
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -52 (dBm), Counter =  1718
<info> app: RSSI = -49 (dBm), Counter =  1720
<info> app: RSSI = -49 (dBm), Counter =  1721
<info> app: RSSI = -48 (dBm), Counter =  1722
<info> app: RSSI = -49 (dBm), Counter =  1724
<info> app: RSSI = -50 (dBm), Counter =  1725
<info> app: RSSI = -51 (dBm), Counter =  1728
<info> app: RSSI = -48 (dBm), Counter =  1730
<info> app: RSSI = -51 (dBm), Counter =  1732
<info> app: RSSI = -48 (dBm), Counter =  1733
<info> app: RSSI = -48 (dBm), Counter =  1734
<info> app: RSSI = -48 (dBm), Counter =  1735
<info> app: RSSI = -48 (dBm), Counter =  1737
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -42 (dBm), Counter =  1738
<info> app: RSSI = -42 (dBm), Counter =  1739
<info> app: RSSI = -42 (dBm), Counter =  1740
<info> app: RSSI = -44 (dBm), Counter =  1741
<info> app: RSSI = -48 (dBm), Counter =  1742
<info> app: RSSI = -49 (dBm), Counter =  1744
<info> app: RSSI = -48 (dBm), Counter =  1745
<info> app: RSSI = -46 (dBm), Counter =  1746
<info> app: RSSI = -46 (dBm), Counter =  1747
<info> app: RSSI = -47 (dBm), Counter =  1748
<info> app: RSSI = -47 (dBm), Counter =  1749
<info> app: RSSI = -48 (dBm), Counter =  1750
<info> app: RSSI = -47 (dBm), Counter =  1752
<info> app: RSSI = -49 (dBm), Counter =  1753
<info> app: RSSI = -43 (dBm), Counter =  1754
<info> app: RSSI = -47 (dBm), Counter =  1755
<info> app: RSSI = -45 (dBm), Counter =  1756
<info> app: RSSI = -43 (dBm), Counter =  1757
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -45 (dBm), Counter =  1758
<info> app: RSSI = -45 (dBm), Counter =  1759
<info> app: RSSI = -44 (dBm), Counter =  1760
<info> app: RSSI = -44 (dBm), Counter =  1762
<info> app: RSSI = -44 (dBm), Counter =  1763
<info> app: RSSI = -44 (dBm), Counter =  1764
<info> app: RSSI = -44 (dBm), Counter =  1764
<info> app: RSSI = -44 (dBm), Counter =  1765
<info> app: RSSI = -44 (dBm), Counter =  1766
<info> app: RSSI = -44 (dBm), Counter =  1767
<info> app: RSSI = -44 (dBm), Counter =  1769
<info> app: RSSI = -44 (dBm), Counter =  1771
<info> app: RSSI = -44 (dBm), Counter =  1772
<info> app: RSSI = -44 (dBm), Counter =  1773
<info> app: RSSI = -44 (dBm), Counter =  1774
<info> app: RSSI = -44 (dBm), Counter =  1775
<info> app: RSSI = -44 (dBm), Counter =  1776
<info> app: RSSI = -44 (dBm), Counter =  1777
<info> app: RSSI = -43 (dBm), Counter =  1777
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -48 (dBm), Counter =  1798
<info> app: RSSI = -46 (dBm), Counter =  1800
<info> app: RSSI = -48 (dBm), Counter =  1801
<info> app: RSSI = -46 (dBm), Counter =  1802
<info> app: RSSI = -46 (dBm), Counter =  1803
<info> app: RSSI = -46 (dBm), Counter =  1805
<info> app: RSSI = -47 (dBm), Counter =  1806
<info> app: RSSI = -47 (dBm), Counter =  1808
<info> app: RSSI = -44 (dBm), Counter =  1809
<info> app: RSSI = -47 (dBm), Counter =  1810
<info> app: RSSI = -47 (dBm), Counter =  1811
<info> app: RSSI = -45 (dBm), Counter =  1812
<info> app: RSSI = -46 (dBm), Counter =  1813
<info> app: RSSI = -47 (dBm), Counter =  1814
<info> app: RSSI = -48 (dBm), Counter =  1815
<info> app: RSSI = -49 (dBm), Counter =  1816
<info> app: RSSI = -46 (dBm), Counter =  1817
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -49 (dBm), Counter =  1838
<info> app: RSSI = -48 (dBm), Counter =  1839
<info> app: RSSI = -52 (dBm), Counter =  1840
<info> app: RSSI = -49 (dBm), Counter =  1841
<info> app: RSSI = -51 (dBm), Counter =  1842
<info> app: RSSI = -53 (dBm), Counter =  1843
<info> app: RSSI = -49 (dBm), Counter =  1844
<info> app: RSSI = -49 (dBm), Counter =  1845
<info> app: RSSI = -49 (dBm), Counter =  1846
<info> app: RSSI = -49 (dBm), Counter =  1849
<info> app: RSSI = -52 (dBm), Counter =  1850
<info> app: RSSI = -48 (dBm), Counter =  1851
<info> app: RSSI = -51 (dBm), Counter =  1852
<info> app: RSSI = -49 (dBm), Counter =  1853
<info> app: RSSI = -49 (dBm), Counter =  1854
<info> app: RSSI = -54 (dBm), Counter =  1855
<info> app: RSSI = -48 (dBm), Counter =  1856
<info> app: RSSI = -48 (dBm), Counter =  1857
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -44 (dBm), Counter =  1878
<info> app: RSSI = -44 (dBm), Counter =  1878
<info> app: RSSI = -43 (dBm), Counter =  1879
<info> app: RSSI = -43 (dBm), Counter =  1879
<info> app: RSSI = -44 (dBm), Counter =  1880
<info> app: RSSI = -43 (dBm), Counter =  1881
<info> app: RSSI = -43 (dBm), Counter =  1882
<info> app: RSSI = -43 (dBm), Counter =  1882
<info> app: RSSI = -43 (dBm), Counter =  1883
<info> app: RSSI = -43 (dBm), Counter =  1883
<info> app: RSSI = -43 (dBm), Counter =  1884
<info> app: RSSI = -43 (dBm), Counter =  1884
<info> app: RSSI = -43 (dBm), Counter =  1885
<info> app: RSSI = -43 (dBm), Counter =  1886
<info> app: RSSI = -43 (dBm), Counter =  1886
<info> app: RSSI = -44 (dBm), Counter =  1887
<info> app: RSSI = -44 (dBm), Counter =  1887
<info> app: RSSI = -43 (dBm), Counter =  1888
<info> app: RSSI = -43 (dBm), Counter =  1888
<info> app: RSSI = -45 (dBm), Counter =  1889
<info> app: RSSI = -43 (dBm), Counter =  1889
<info> app: RSSI = -44 (dBm), Counter =  1890
<info> app: RSSI = -44 (dBm), Counter =  1890
<info> app: RSSI = -43 (dBm), Counter =  1891
<info> app: RSSI = -43 (dBm), Counter =  1891
<info> app: RSSI = -43 (dBm), Counter =  1892
<info> app: RSSI = -43 (dBm), Counter =  1892
<info> app: RSSI = -43 (dBm), Counter =  1893
<info> app: RSSI = -43 (dBm), Counter =  1893
<info> app: RSSI = -43 (dBm), Counter =  1894
<info> app: RSSI = -43 (dBm), Counter =  1894
<info> app: RSSI = -43 (dBm), Counter =  1895
<info> app: RSSI = -43 (dBm), Counter =  1895
<info> app: RSSI = -44 (dBm), Counter =  1896
<info> app: RSSI = -44 (dBm), Counter =  1896
<info> app: RSSI = -45 (dBm), Counter =  1897
<info> app: RSSI = -45 (dBm), Counter =  1897
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -49 (dBm), Counter =  1919
<info> app: RSSI = -52 (dBm), Counter =  1921
<info> app: RSSI = -50 (dBm), Counter =  1925
<info> app: RSSI = -51 (dBm), Counter =  1926
<info> app: RSSI = -51 (dBm), Counter =  1927
<info> app: RSSI = -51 (dBm), Counter =  1928
<info> app: RSSI = -50 (dBm), Counter =  1929
<info> app: RSSI = -51 (dBm), Counter =  1931
<info> app: RSSI = -49 (dBm), Counter =  1933
<info> app: RSSI = -50 (dBm), Counter =  1934
<info> app: RSSI = -50 (dBm), Counter =  1935
<info> app: RSSI = -51 (dBm), Counter =  1936
<info> app: RSSI = -50 (dBm), Counter =  1937
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -50 (dBm), Counter =  1938
<info> app: RSSI = -51 (dBm), Counter =  1941
<info> app: RSSI = -51 (dBm), Counter =  1942
<info> app: RSSI = -51 (dBm), Counter =  1943
<info> app: RSSI = -50 (dBm), Counter =  1944
<info> app: RSSI = -50 (dBm), Counter =  1945
<info> app: RSSI = -51 (dBm), Counter =  1946
<info> app: RSSI = -51 (dBm), Counter =  1947
<info> app: RSSI = -50 (dBm), Counter =  1948
<info> app: RSSI = -50 (dBm), Counter =  1949
<info> app: RSSI = -51 (dBm), Counter =  1950
<info> app: RSSI = -49 (dBm), Counter =  1952
<info> app: RSSI = -49 (dBm), Counter =  1953
<info> app: RSSI = -51 (dBm), Counter =  1954
<info> app: RSSI = -50 (dBm), Counter =  1955
<info> app: RSSI = -50 (dBm), Counter =  1956
<info> app: RSSI = -51 (dBm), Counter =  1957
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -49 (dBm), Counter =  1978
<info> app: RSSI = -51 (dBm), Counter =  1979
<info> app: RSSI = -48 (dBm), Counter =  1980
<info> app: RSSI = -48 (dBm), Counter =  1981
<info> app: RSSI = -52 (dBm), Counter =  1982
<info> app: RSSI = -49 (dBm), Counter =  1983
<info> app: RSSI = -50 (dBm), Counter =  1984
<info> app: RSSI = -48 (dBm), Counter =  1985
<info> app: RSSI = -48 (dBm), Counter =  1986
<info> app: RSSI = -48 (dBm), Counter =  1987
<info> app: RSSI = -48 (dBm), Counter =  1988
<info> app: RSSI = -50 (dBm), Counter =  1989
<info> app: RSSI = -51 (dBm), Counter =  1991
<info> app: RSSI = -48 (dBm), Counter =  1992
<info> app: RSSI = -48 (dBm), Counter =  1993
<info> app: RSSI = -48 (dBm), Counter =  1994
<info> app: RSSI = -49 (dBm), Counter =  1995
<info> app: RSSI = -48 (dBm), Counter =  1996
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -43 (dBm), Counter =  1999
<info> app: RSSI = -44 (dBm), Counter =  2000
<info> app: RSSI = -43 (dBm), Counter =  2001
<info> app: RSSI = -44 (dBm), Counter =  2004
<info> app: RSSI = -44 (dBm), Counter =  2007
<info> app: RSSI = -45 (dBm), Counter =  2009
<info> app: RSSI = -45 (dBm), Counter =  2010
<info> app: RSSI = -44 (dBm), Counter =  2012
<info> app: RSSI = -45 (dBm), Counter =  2015
<info> app: RSSI = -44 (dBm), Counter =  2017
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -51 (dBm), Counter =  2038
<info> app: RSSI = -52 (dBm), Counter =  2039
<info> app: RSSI = -52 (dBm), Counter =  2040
<info> app: RSSI = -49 (dBm), Counter =  2041
<info> app: RSSI = -49 (dBm), Counter =  2042
<info> app: RSSI = -52 (dBm), Counter =  2043
<info> app: RSSI = -55 (dBm), Counter =  2044
<info> app: RSSI = -54 (dBm), Counter =  2045
<info> app: RSSI = -49 (dBm), Counter =  2046
<info> app: RSSI = -54 (dBm), Counter =  2047
<info> app: RSSI = -49 (dBm), Counter =  2048
<info> app: RSSI = -51 (dBm), Counter =  2049
<info> app: RSSI = -48 (dBm), Counter =  2050
<info> app: RSSI = -57 (dBm), Counter =  2051
<info> app: RSSI = -51 (dBm), Counter =  2054
<info> app: RSSI = -49 (dBm), Counter =  2056
<info> app: Scan timed out.
<info> app: Starting scan on 1Mbps.
<info> app: 
 Scanning Start

<info> app: RSSI = -44 (dBm), Counter =  2060

Scanning settings and start routine are standard ones.

Please take a look and maybe aynone had similar issue?

Thanks!

MikeP · Answer

Hi, 
 I have to answer it myself. Tried playing with scan interval and window. As standard, interval is 100ms , window is 50ms. So with the time advert transmission was moving toward non scanning window. Also when scanning was started was important. After setting both window and interval to the same value, everything is received correctly. 
 Hope it will help others as well. 
 Mike