Receiving HCI_HARDWARE_ERROR_EVENT ISR delay error

[Nicolas B.]

Device: STM32WB55

Hi Community,

We are receiving HCI_HARDWARE_ERROR_EVENT with code 0x04 from bluetooth full stack (version 1.18 up to 1.24 tested), while advertising and C1 enters STOP1. It happens randomly, and the device becomes sometimes unconnectable after this unless we reset the stack.

We are NOT using STM32CubeWB, but followed recommandations found in AN5289 regarding PLL management and entering/leaving STOP1 mode.

Any insight on what can cause this and how to fix it properly ?

Thanks,

 

[Remy ISSALYS]

Hello,

The hardware code 0x04 means an ISR delay error was detected. This can be caused by a flash operation (write or erase) on CPU1. To protect the CPU2 timing, the application on CPU1 must implement the algorithm described in Section 4.7 of AN5289 to write or erase flash memory. When the CPU executes code from flash memory, it stalls as soon as a write or erase operation starts, so it can delay the ISR on the CPU2 side if the flash operation is performed without following the specified algorithm.

You can look at the following application, which demonstrates the capability to erase/write flash while the RF is active. The application embeds the flash driver, which implements the algorithm described in AN5289:

STM32Cube_FW_WB_V1.24.0\Projects\P-NUCLEO-WB55.Nucleo\Applications\BLE\BLE_RfWithFlash

Do you perform flash operations in your application without implementing the algorithm?

If not, could you share more information about your application and how you manage the PLL and low power? Are you using the low-power manager?

Best Regards

[Imen.D]

Hello ​@Nicolas B.,

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We look forward an update from you.

[Nicolas B.]

​@Remy ISSALYS, ​@Imen.D ,

Thanks for replying, I have been away from this subject for a while, hence my late reply.

No, I am not trying to write/erase flash memory during the times the problem arises. It happens randomly when my device is using STOP mode.

Here attached is the relevant code (I am not using Cube IDE nor any Cube package).

Kind Regards,

Nicolas