RE: [nRF52840 USB Dongle] Irregular Notification Intervals from nRF52832 Peripheral (Expected 7.5ms, Observed 0–40ms)

Edvin — Thu, 19 Jun 2025 20:42:06 GMT

Ok. A sniffer trace would probably help, shedding some light to what rate the packets are actually coming. It may be that you should just copy the data out of the buffer, and into another buffer, and handle it later outside the notification callback as well, but we can look into that after studying the sniffer trace.

Best regards,

Edvin

RE: [nRF52840 USB Dongle] Irregular Notification Intervals from nRF52832 Peripheral (Expected 7.5ms, Observed 0–40ms)

Yan Jose — Thu, 19 Jun 2025 13:36:05 GMT

Each packet is typically 240 bytes long.

RE: [nRF52840 USB Dongle] Irregular Notification Intervals from nRF52832 Peripheral (Expected 7.5ms, Observed 0–40ms)

Edvin — Thu, 19 Jun 2025 12:37:58 GMT

Perhaps you can try to capture a sniffer trace of the connection. For this, you can use the nRF Sniffer for Bluetooth LE.

Perhaps there are some retransmissions happening.

How long is typically the packets that are received?

Best regards,

Edvin

RE: [nRF52840 USB Dongle] Irregular Notification Intervals from nRF52832 Peripheral (Expected 7.5ms, Observed 0–40ms)

Yan Jose — Thu, 19 Jun 2025 08:41:59 GMT

[00:00:05.121,337] <inf> main: Notify: interval 5 ms
[00:00:05.127,502] <inf> main: Notify: interval 6 ms
[00:00:05.132,385] <inf> main: Notify: interval 5 ms
[00:00:05.137,268] <inf> main: Notify: interval 5 ms
[00:00:05.143,524] <inf> main: Notify: interval 6 ms
[00:00:05.161,956] <inf> main: Notify: interval 18 ms
[00:00:05.166,931] <inf> main: Notify: interval 5 ms
[00:00:05.191,467] <inf> main: Notify: interval 25 ms
[00:00:05.196,350] <inf> main: Notify: interval 5 ms
[00:00:05.202,484] <inf> main: Notify: interval 6 ms
[00:00:05.207,397] <inf> main: Notify: interval 5 ms
[00:00:05.263,977] <inf> main: Notify: interval 56 ms
[00:00:05.268,890] <inf> main: Notify: interval 5 ms
[00:00:05.307,952] <inf> main: Notify: interval 39 ms
[00:00:05.323,974] <inf> main: Notify: interval 16 ms
[00:00:05.328,887] <inf> main: Notify: interval 5 ms
[00:00:05.341,949] <inf> main: Notify: interval 13 ms
[00:00:05.346,832] <inf> main: Notify: interval 5 ms
[00:00:05.352,996] <inf> main: Notify: interval 6 ms
[00:00:05.357,910] <inf> main: Notify: interval 5 ms
[00:00:05.372,436] <inf> main: Notify: interval 15 ms
[00:00:05.377,349] <inf> main: Notify: interval 5 ms
[00:00:05.386,993] <inf> main: Notify: interval 9 ms
[00:00:05.401,947] <inf> main: Notify: interval 15 ms
[00:00:05.406,860] <inf> main: Notify: interval 5 ms
[00:00:05.416,992] <inf> main: Notify: interval 10 ms
[00:00:05.446,472] <inf> main: Notify: interval 30 ms
[00:00:05.459,472] <inf> main: Notify: interval 13 ms
[00:00:05.464,355] <inf> main: Notify: interval 5 ms
[00:00:05.469,207] <inf> main: Notify: interval 5 ms
[00:00:05.489,471] <inf> main: Notify: interval 20 ms
[00:00:05.494,354] <inf> main: Notify: interval 5 ms
[00:00:05.499,237] <inf> main: Notify: interval 5 ms
[00:00:05.505,493] <inf> main: Notify: interval 6 ms
[00:00:05.521,942] <inf> main: Notify: interval 16 ms
[00:00:05.527,252] <inf> main: Notify: interval 6 ms
[00:00:05.536,987] <inf> main: Notify: interval 9 ms
[00:00:05.551,940] <inf> main: Notify: interval 15 ms
[00:00:05.556,854] <inf> main: Notify: interval 5 ms
[00:00:05.566,986] <inf> main: Notify: interval 10 ms
[00:00:05.611,968] <inf> main: Notify: interval 45 ms
[00:00:05.616,882] <inf> main: Notify: interval 5 ms
[00:00:05.622,985] <inf> main: Notify: interval 6 ms
[00:00:05.627,899] <inf> main: Notify: interval 5 ms
[00:00:05.641,937] <inf> main: Notify: interval 14 ms
[00:00:05.646,881] <inf> main: Notify: interval 5 ms
[00:00:05.656,982] <inf> main: Notify: interval 10 ms
[00:00:05.671,966] <inf> main: Notify: interval 15 ms
[00:00:05.676,879] <inf> main: Notify: interval 5 ms
[00:00:05.687,011] <inf> main: Notify: interval 10 ms
[00:00:05.701,965] <inf> main: Notify: interval 15 ms
[00:00:05.706,878] <inf> main: Notify: interval 5 ms
[00:00:05.716,979] <inf> main: Notify: interval 10 ms
[00:00:05.731,964] <inf> main: Notify: interval 15 ms
[00:00:05.736,877] <inf> main: Notify: interval 5 ms
[00:00:05.747,009] <inf> main: Notify: interval 10 ms
[00:00:05.761,962] <inf> main: Notify: interval 15 ms
[00:00:05.767,242] <inf> main: Notify: interval 6 ms
[00:00:05.777,008] <inf> main: Notify: interval 9 ms
[00:00:05.791,961] <inf> main: Notify: interval 15 ms
[00:00:05.796,875] <inf> main: Notify: interval 5 ms
[00:00:05.806,976] <inf> main: Notify: interval 10 ms
[00:00:05.821,960] <inf> main: Notify: interval 15 ms
[00:00:05.833,068] <inf> main: Notify: interval 12 ms
[00:00:05.837,982] <inf> main: Notify: interval 4 ms
[00:00:05.851,959] <inf> main: Notify: interval 14 ms
[00:00:05.856,872] <inf> main: Notify: interval 5 ms
[00:00:05.867,004] <inf> main: Notify: interval 10 ms
[00:00:05.881,958] <inf> main: Notify: interval 15 ms
[00:00:05.886,871] <inf> main: Notify: interval 5 ms
[00:00:05.897,003] <inf> main: Notify: interval 10 ms
[00:00:05.911,956] <inf> main: Notify: interval 15 ms
[00:00:05.916,870] <inf> main: Notify: interval 5 ms
[00:00:05.927,001] <inf> main: Notify: interval 10 ms
[00:00:05.971,954] <inf> main: Notify: interval 45 ms
[00:00:05.976,837] <inf> main: Notify: interval 5 ms
[00:00:05.982,971] <inf> main: Notify: interval 6 ms
[00:00:05.987,884] <inf> main: Notify: interval 5 ms
[00:00:06.001,953] <inf> main: Notify: interval 14 ms
[00:00:06.007,263] <inf> main: Notify: interval 6 ms
[00:00:06.016,998] <inf> main: Notify: interval 9 ms
[00:00:06.046,936] <inf> main: Notify: interval 30 ms
[00:00:06.059,997] <inf> main: Notify: interval 13 ms
[00:00:06.064,880] <inf> main: Notify: interval 5 ms
[00:00:06.069,763] <inf> main: Notify: interval 5 ms
[00:00:06.075,958] <inf> main: Notify: interval 6 ms
[00:00:06.080,841] <inf> main: Notify: interval 5 ms
[00:00:06.089,965] <inf> main: Notify: interval 9 ms
[00:00:06.094,909] <inf> main: Notify: interval 5 ms
[00:00:06.106,994] <inf> main: Notify: interval 12 ms
[00:00:06.136,993] <inf> main: Notify: interval 30 ms
[00:00:06.151,947] <inf> main: Notify: interval 15 ms
[00:00:06.156,860] <inf> main: Notify: interval 5 ms
[00:00:06.166,992] <inf> main: Notify: interval 10 ms
[00:00:06.181,945] <inf> main: Notify: interval 15 ms
[00:00:06.186,859] <inf> main: Notify: interval 5 ms
[00:00:06.196,990] <inf> main: Notify: interval 10 ms
[00:00:06.225,463] <inf> main: Notify: interval 29 ms
[00:00:06.238,494] <inf> main: Notify: interval 13 ms
[00:00:06.243,377] <inf> main: Notify: interval 5 ms
[00:00:06.254,974] <inf> main: Notify: interval 11 ms
[00:00:06.260,223] <inf> main: Notify: interval 6 ms
[00:00:06.265,106] <inf> main: Notify: interval 5 ms
[00:00:06.270,965] <inf> main: Notify: interval 5 ms
[00:00:06.282,531] <inf> main: Notify: interval 12 ms
[00:00:06.287,445] <inf> main: Notify: interval 5 ms
[00:00:06.331,939] <inf> main: Notify: interval 44 ms
[00:00:06.336,822] <inf> main: Notify: interval 5 ms
[00:00:06.342,987] <inf> main: Notify: interval 6 ms
[00:00:06.347,900] <inf> main: Notify: interval 5 ms
[00:00:06.361,999] <inf> main: Notify: interval 14 ms
[00:00:06.376,983] <inf> main: Notify: interval 15 ms
[00:00:06.391,937] <inf> main: Notify: interval 15 ms
[00:00:06.396,881] <inf> main: Notify: interval 5 ms
[00:00:06.406,982] <inf> main: Notify: interval 10 ms
[00:00:06.421,966] <inf> main: Notify: interval 15 ms
[00:00:06.426,879] <inf> main: Notify: interval 5 ms
[00:00:06.437,011] <inf> main: Notify: interval 10 ms
[00:00:06.451,965] <inf> main: Notify: interval 15 ms
[00:00:06.456,878] <inf> main: Notify: interval 5 ms
[00:00:06.466,979] <inf> main: Notify: interval 10 ms
[00:00:06.481,964] <inf> main: Notify: interval 15 ms
[00:00:06.486,877] <inf> main: Notify: interval 5 ms
[00:00:06.497,375] <inf> main: Notify: interval 11 ms
[00:00:06.511,962] <inf> main: Notify: interval 14 ms
[00:00:06.516,876] <inf> main: Notify: interval 5 ms
[00:00:06.526,977] <inf> main: Notify: interval 10 ms
[00:00:06.541,961] <inf> main: Notify: interval 15 ms
[00:00:06.546,875] <inf> main: Notify: interval 5 ms

I inserted the following code into the notify_cb function to log the receive interval via the debugger:

The logged intervals match what I observed earlier, so it seems the callback function is actually being invoked at those intervals.

RE: [nRF52840 USB Dongle] Irregular Notification Intervals from nRF52832 Peripheral (Expected 7.5ms, Observed 0–40ms)

Turbo J — Thu, 19 Jun 2025 06:37:28 GMT

Try to measure time on the receiving device and not on the PC. Windows timing can be interesting. See also timeBeginPeriod().

I also recommend putting an USB 2.0 (or higher) hub between the PC host and the NRF device.