Hello, I have a question regarding BLE Connection.
Test Condition:
- SDK: nRF5_SDK_15.3.0
- Softdevice: s140_nrf52_6.1.1
- Target hardware: PCA10040(nRF52832), custom board(nRF52840)
Problem:
- Connection from Android phone fails from time to time
Notes:
- Only some phones show the problem
- nRF52832 shows more error than nRF52840 ( for example 10% in 52832(10 fails on 100 trial), while 1% in 52840 )
- I captured the failing and success case but failed to identify difference.
Following capture shows normal case.
nRF5 stops advertising(Orange) as soon as it gets CONNECT_REQ(Purple).
And master and slave meet later when CONNECT_REQ specified. ( Green and Blue packet )
Following 2 captures show failing case.
IFS between orange(ADV_IND) and purple(CONNECT_REQ) is 152us both normal and failing case.
nRF5 keeps adverting and does not respond to master's packet.
I don't think it's from interference because of the first failing case.
Here is the zoomed-in picture of the first failing case.
nRF5 has definitely received the purple packet and we know it from the fact that the third ADV_IND is deferred ( 528us + 652 us ).
Usually, the third ADV packet is sent around 874us after the beginning of second ADV packet.
I hope it is not an inherent problem of nRF5.
Please give me some measure to get around this problem.
I think it may help if the gap between ADV packets in one event can be widen.
Thank you.
Best regards,
Jake
