about long-term wireless stability of the QN9080

[jung-jin]

Hello

Our product is using QN9080.
It disconnects well between 5 and 15 minutes after Bluetooth connection.
The wireless environment is at the level of a general office and is not noisy.
The goal is to operate stably for more than 8 hours.
The transmission interval is 40 ms, and the communication speed is around 30 kbps.
What variables can be adjusted to increase wireless connection stability?

ex)
(1) Increase memory or queue size?
- gMaxL2caQueueSize_c ?
- gPrepareWriteQueueSize_c ?

(2) Increase timeout or some time parameter?
- gBleDefaultTxTime_c?
- connection interval or latency?

(3) or user coded phy?

Please let me know if there is a way to increase the stability of wireless connection by adjusting certain parameters.

Best Regards,
jung jin

[acklyn]

QN9080 integrates a 32-bit ARM Cortex-M4F core with Bluetooth Low Energy (v5.0)

compliant radio, link controller, host stack and GATT profiles. The 32-bit ARM Cortex-M4F

MCU and on-chip  memory provides additional signal processing and scope to run scentsy workstation

applications for a true single-chip Bluetooth Low Energy (v5.0) solution.

[Ricardo_Zamora]

Hi jung jin,

Hope you are doing well. How are you connecting the QN9080? (Other device or to another QN9080).

What SDK example are you using as a base? What modifications did you make?

Are you using the QN9080DK board? Or is it a custom board?

Best Regards,

Ricardo

[jung-jin]

Hi Ricardo.

(1) QN9080 device - Smart phone (android)
(2) Our project based on private_profile_client
- Bluetooth-related functions have not been modified, but only application-related functions.
(3) Our custom board

<more information>
- Bluetooth connection is sometimes disconnected between 10 and 15 minutes.
- Sometimes, it's stable for more than an hour.
- Sometimes the device reboots when the connection is disconnected.

If there's a way to improve the stability of wireless communication, I hope you can let me know.

Best Regards,
jung-jin

[Ricardo_Zamora]

Hi jung-jin,

Are you having this issue with the private_profile_client without any modification? Have you try with two QN9080 boards? We don't know if the disconnection is caused by the QN9080 or by the android application.

By any chance, could you print the disconnection reason?

In the gConnEvtDisconnected_c case of the BleApp_ConnectionCallback, please add these lines:

Serial_Print(gAppSerMgrIf, "Disconnection Reason:  ", gNoBlock_d);

Serial_PrintDec(gAppSerMgrIf, pConnectionEvent->eventData.disconnectedEvent.reason);

Serial_Print(gAppSerMgrIf, ".\n\r", gNoBlock_d);

What is the Disconnection Reason?

Regards,

Ricardo

[jung-jin]

Hi Ricardo.

When I tested with the proposed code, the disconnection message was not printed.
When I checked, it was not a Bluetooth disconnection problem, and a sudden reboot occurred during operation.
I'm not sure why the device suddenly reboots randomly during Bluetooth communication.

Is there any way to print out a message to find out the cause of the reboot?
Our company's three products developed by applying QN9080 seem to show similar trends.
- It operates for as short as 5 minutes, as long as 1 hour, and then suddenly reboots.
- Bluetooth connection will be disconnected when rebooting.

Best Regards,
jung-jin

[Ricardo_Zamora]

Hi jung-jin,

Can you please check this register?

(From the User Manual)

This could help us to identify the issue you are presenting.

Do you have a QN9080DK? Is this issue also happening in our board? This to discard an issue with your custom board.

Regards,

Ricardo

[jung-jin · Accepted solution]

Finally, it was confirmed that reboot occurs randomly due to i2C communication
Decreasing I2C speed from 400 kHz to 100 kHz resolved the issue
I don't know why it reboots sometimes when I set I2C to 400 kHz.

Thank you for your reply.

[jung-jin]

Hi Ricardo.

Currently, I am reading the reset source register after initializing uart.
Is it right to read it as below?

Serial_Print(gAppSerMgrIf, "RST_CAUSE_SRC : %x", SYSCON->RST_CAUSE_SRC & SYSCON_RST_CAUSE_SRC_RESET_CAUSE_MASK, gAllowToBlock_d);

The register value read after a sudden reboot occurs is 0x1FF.
Does this mean that power on reset has occurred?

+ more info

 - Rebooting occurs even when Bluetooth is not connected. (Waiting with only advertising)
 - When it's okay, it works normally for more than 5 hours.
 - Sometimes the QN9080 board reboots in five minutes.

Regards,

Jing-jin