Issue with establishing BLE client connection

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KiKo_4837791
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Level 1
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Hello,

We have a simple BLE keyboard product that uses CYBLE-012011-00 module. We are having an issue with a newer batch of CYBLE modules with the BLE connection failing to be established. In addition to our own firmware, the problem persists  with example projects such as BLE Keyboard and BLE Mouse, and with different host devices (Linux PC, Android, iOS, Windows PC). We have none of these issues with an older batch (2017) of the same modules.

We can replicate the issue by uploading an example firmware (BLE Keyboard) to the older batch. BLE connection is established succesfully and the device works as expected. With the newer batch, the device is seen to transmit the BLE beacon. However, when BLE connection is attempted, generic error is returned on the HCI level and connection fails to establish.

I've included BT monitoring dumps from Bluez taken with the older and newer modules. Also included are images of the module markings. (Note: there's some modification done to the antenna in the older batch. Having this mod done with the newer batch did not resolve the issue)

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1 Solution
Yugandhar
Moderator
Moderator
Moderator
1000 replies posted 5 likes given First comment on blog

Hello,

Setting the ECO Capacitance trim values in the firmware might helps. If any BLE module is used, the trim values should be changed to the values provided by that module’s datasheet. Please refer to this KBA ECO Capacitance Trim Values for EZ-BLE Modules - KBA218990 for the CAPTRIM Register value.

Please let me know your observations after adding the Cap trim value.

Thanks,
P Yugandhar.

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2 Replies
Yugandhar
Moderator
Moderator
Moderator
1000 replies posted 5 likes given First comment on blog

Hello,

Setting the ECO Capacitance trim values in the firmware might helps. If any BLE module is used, the trim values should be changed to the values provided by that module’s datasheet. Please refer to this KBA ECO Capacitance Trim Values for EZ-BLE Modules - KBA218990 for the CAPTRIM Register value.

Please let me know your observations after adding the Cap trim value.

Thanks,
P Yugandhar.

KiKo_4837791
Level 1
Level 1
First reply posted First question asked First like given

I followed the linked solution and applied the value marked for CYBLE-012011-00. This completely resolved the issue! The connection no longer drops immediately after the connection is made. Thank you very much for the help with this issue.

BR

K Korpelin

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