BLE connection / communication issue with Windows PC

[JourneymanWizard]

Greetings,

Our system consists of three BLE sensors using an nRF52840 to send data back to a central tablet or PC.  We are receiving reports that the sensors take a long time to connect to PCs running Windows 11.  Once connected, it does not seem the link is stable; sometimes the PC will list the sensor as paired, but there does not seem to be any communication.

This issue does not seem to present when the central receiver is an Android tablet or PC running iOS (very limited testing on the latter).

I used an SDK configured as a BLE sniffer and Wireshark to capture communication between a sensor and a (separate) PC running Windows.  I don't have much experience with BLE communications, but it seems like there is a PHY negotiation issue - the systems agree to PHY 2M, but somehow there is a mismatch later?

I have attached the Wireshark capture of the interaction; any insight would be appreciated.

Thank you,

trim.pcapng

[dejans]

Hi,

Based on the Bluetooth Spec v5.2, Vol. 6, Part B, Section 5.3, your issue seems to be related to collisions where link layers of master and slave initiate incompatible procedures.

It might be beneficial to get more information about your setup and environment in which devices operate.

Which NCS version do you use?

Could you provide more information about your application?

Could you show application log when the issue occurs? Are there any errors in the log?

Best regards,
Dejan

[JourneymanWizard]

The previous logs were captured in an engineering office space with the sensor and PC ~1m apart and the sniffer a few cm away from the sensor.

I am using the nRF52-DK SDK for packet sniffing.

The application is intended for outside (sensor) use.  The sensors send data from an IMU to a PC.

Unfortunately the sensor does not generate a log.

[dejans]

Hi,

Which sensors do you use?

dejans said:

Could you provide more information about your application?

What is your application supposed to be doing? Is your application based on any of our Bluetooth samples? How often do your sensors send data? When are sensors expected to send data? Do sensors send data one by one? Could you provide some additional details?

JourneymanWizard said:

The sensors send data from an IMU to a PC.

For testing, have you tried to use only one or two BLE sensors instead of three? Is the error still there when you use one or two sensors?

dejans said:

Which NCS version do you use?

Please provide NCS version that you used in your application.

Best regards,
Dejan