Random BLE Disconnects + PWM

RE: Random BLE Disconnects + PWM

Sigurd — Wed, 30 Jun 2021 19:54:16 GMT

[quote user=""]The FW update after which this issue seems to have been introduced[/quote]

Without any logs it is difficult to figure out what the root cause is. If you have the firmware before and after the update, you might want to do a review and look more into what other changes the update did in your firmware, but if it was a very big update with a lot of changes, some nrf_logs that shows the failure might be needed to figure this one out.

RE: Random BLE Disconnects + PWM

nikolozka — Tue, 29 Jun 2021 14:40:25 GMT

We're using SDK 15.3 with S132v6.1

RE: Random BLE Disconnects + PWM

Sigurd — Tue, 29 Jun 2021 14:06:35 GMT

Ok. What nRF5-SDK version, and what SoftDevice variant and version are you using?

RE: Random BLE Disconnects + PWM

nikolozka — Tue, 29 Jun 2021 13:18:21 GMT

That is my suspicion as well, Though I haven't been able to observe this with either the debugger or nrf connect or packet sniffer connected. The test devices I'm working this haven;t exhibited this behavior, but It does happen on deployed devices from time to time.
To add some more info we're using:

NRF_SDH_CLOCK_LF_SRC 0
NRF_SDH_CLOCK_LF_ACCURACY 1
NRF_SDH_CLOCK_LF_RC_TEMP_CTIV 2
NRF_SDH_CLOCK_LF_RC_CTIV 16

The connection parameters are pretty standard too:

MIN_CONN_INTERVAL MSEC_TO_UNITS(15, UNIT_1_25_MS)
MAX_CONN_INTERVAL MSEC_TO_UNITS(45, UNIT_1_25_MS)
SLAVE_LATENCY 3
CONN_SUP_TIMEOUT MSEC_TO_UNITS(6000, UNIT_10_MS)

The disconnects happen both on android and IOS, in our production app as well as our internal test app that usesdifferent bluetooth implementation. So there's a high likelyhood of the diconnect originating on the HW side

RE: Random BLE Disconnects + PWM

Sigurd — Tue, 29 Jun 2021 13:10:46 GMT

Hi,

[quote user=""]the connection gets dropped immediately[/quote]

Do you know what the disconnect reason is when this happens? Based on your description, I assume it's 8 (BLE_HCI_CONNECTION_TIMEOUT) ?

[quote user=""]NRF_DRV_PWM_INSTANCE(0); it has recently caught my attention that this could be using TIMER0[/quote]

No, the PWM peripheral is clocked directly from the clock tree, it does not use the TIMER.

RE: Random BLE Disconnects + PWM

nikolozka — Thu, 24 Jun 2021 13:51:38 GMT

The device doesn't crash nor restart.

Its keeps advertising but becoms "unconnectable" untill it goes to sleep after we stop attempting to connect.

This is triggered from BLE_ADV_EVT_IDLE if certain interrupts haven't been received for a while.

Sleep mode in our case is just disabling peripherals & going to WFE() (no going to POWEROFF or any such operation)

it seems like BLE_ADV_EVT_IDLE + restarting advertising clears the issue but it's hard to tell for certain what is causing this behavior

There is logging functionality on the HW side ofcourse but I haven't been able to reproduce this behavior under test conditions / with debugger connected

RE: Random BLE Disconnects + PWM

awneil — Thu, 24 Jun 2021 13:40:36 GMT

Is the device crashing & restarting ?

[quote userid="95197" url="~/f/nordic-q-a/76725/random-ble-disconnects-pwm"]The App side logs seem to indicate that the diconnection comes from the HW side[/quote]

Do you have some HW side logs ?