BUG REPORT: ST67W6X NCP (SDK 2.0.89) – High-Severity BLE GATT Server Defects (Data Corruption >23B & Missing CCCD)

[RomThi]

Dear ST Support Team / FAE Team,

We are currently developing a product using the ST67W611M1 Wi-Fi/BLE combo module on an STM32H563ZI host platform (using X-CUBE-ST67W61 / W61 AT driver).

During our integration and validation phase, we uncovered two high-severity bugs within the ST67W6X NCP firmware (SDK Version 2.0.89 / BT Stack Version 1.9.56) that render the BLE GATT server unusable for production:

1. GATT Read-Data Corruption: Any characteristic value set via AT+BLEGATTSRD that exceeds 23 bytes (the default ATT MTU payload boundary) gets systematically corrupted. A 32-bit little-endian length field is overwritten directly into the data buffer starting exactly at offset 23.
2. Missing Notify Property & CCC Descriptor: When registering a characteristic with the Notify property enabled, the NCP's internal database (AT+BLEGATTSCHAR?) reflects the property correctly, but the exported GATT database exposed to the BLE client drops the Notify bit and completely omits the Client Characteristic Configuration Descriptor (0x2902).

We have fully isolated these issues and created a highly detailed, deterministic bug report containing environmental data, exact reproduction steps, data evidence, and specific pointers to the potential root causes in the NCP stack.

Attached to this ticket, please find:

• The comprehensive bug report (ST67W6X_Bug_Report.txt)

Since these defects severely block our development roadmap and force us into highly restrictive workarounds (limiting all GATT frames to ≤ 23 bytes and avoiding notifications entirely), we kindly ask you to forward this report directly to the Wireless Connectivity / NCP Firmware Engineering Team.

Could you please confirm if these bugs are already known, and whether a newer NCP firmware binary or patch is available to resolve them?

Thank you very much for your support.

Best regards,
Roman

[EPASZ.1]

Using the binary version 2.0.89 when there is a newer version 2.0.106 (and has been for some time), is not recommended. As in this case, I believe both issues were already solved with this release.

Second point is that the Community is not usually the ideal place to report such issues - you can use the official support portal Support Home - STMicroelectronics (under “Open a case”) in the future.

[RomThi]

Hi,
thank you for your help, it now works. At least my first point, that was important. 
I will open a case for support next time. 

Best regards
Roman