nRF5340PDK Data Length Extension

[rick-w]

Hi, I am using the Nordic nRF53PDK, with the Segger IDE, and v1.3.0 of theSDK, and would like to know how to enable Data Length Extensions. I am starting from the SDK \\v1.3.0\nrf\samples\bluetooth\llpm project, as this is a BT5.2 capable project, supporting Low Latency.

For my project, I need to enable Data Length Extension functionality, but can't see where this needs to be added in order to get it to work.

I have tried adding CONFIG_BT_DATA_LEN_UPDATE=y and CONFIG_BT_CTLR_DATA_LENGTH_MAX=234 to the proj.conf file, but this causes an exception to be issues immediately to the debug ouput UART

Any help would be appreciated.

Best Regards,

Rick

[haakonsh]

I believe LLPM uses a tiny payload due to the low-latency nature. If you need more than a few bytes of payload you should not use LLPM. 

 

but this causes an exception to be issues immediately to the debug ouput UART

 Care to share?

[rick-w]

Thanks Haakonsh.

I believe that the exception I was seeing is due to the Arm MPU size, which is configured for a given project, and that by setting CONFIG_BT_DATA_LEN_UPDATE=y, I was overstepping the MPU boundary, which is currently set to 64KRam for the NET processor.

Is there any documentation on changing the MPU size of the ARM code, from within the SDK

Regards,

Rick

[haakonsh]

Can you share the exception?

[rick-w]

My Bad - it's an assert in:

void arm_core_mpu_mark_areas_for_dynamic_regions()
        __ASSERT(0, "Marking %u areas for dynamic regions failed %x %x \n",
            dyn_region_areas_num, dyn_region_areas->start, dyn_region_areas->size);

it appears that if the code size trips over boundary 0x2CA00 (decimal 182748B), then the assertion is called.

Can you point ot the config file where this boundary is set.

Thansk - Rick

[haakonsh]

Is this log from the net core? 

Try increasing the CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE or CONFIG_MAIN_STACK_SIZE in prj.conf of the hci_rpmsg sample.