How to change the default MTU size of the BLE central (ble_app_blinky_c)?

RE: How to change the default MTU size of the BLE central (ble_app_blinky_c)?

Amanda Hsieh — Wed, 23 Oct 2019 12:57:40 GMT

Hi,

You can refer to Vidar Berg's suggestion in this post.

This post also might help.

-Amanda H

RE: How to change the default MTU size of the BLE central (ble_app_blinky_c)?

Dhyanes — Wed, 23 Oct 2019 07:15:02 GMT

Hi,

Thank you for the answers. I want to know how a BLE central can write more than 20 bytes to the BLE peripheral's characteristics. So in reference to your answer, I am not bit clear for data transfers.

regards

Dhyanes

RE: How to change the default MTU size of the BLE central (ble_app_blinky_c)?

Amanda Hsieh — Wed, 23 Oct 2019 06:28:39 GMT

Hi,

Only the client side can write data to the server. Please see the following figure:

-Amanda H.

RE: How to change the default MTU size of the BLE central (ble_app_blinky_c)?

Dhyanes — Tue, 22 Oct 2019 11:35:20 GMT

Hi Amanda,

Thank you for the answers. I am trying to send around 30 bytes from central to a peripheral (non-nrf device). And the invalid data size error comes on the server-side. I am able to send more than 120 bytes to the same peripheral using NRF connect phone application, but I am not able to send them using ble_central_app_blinky application. And I assume the solution you had provided, needs to be worked in client-side, but in this case, I am using different ble peripheral. Please help me with the same.

regards

Dhyanes

RE: How to change the default MTU size of the BLE central (ble_app_blinky_c)?

Amanda Hsieh — Tue, 22 Oct 2019 11:11:56 GMT

Hi Dhyanes,

[quote user="Dhyanes"]I get an invalid data size error as a return statement. [/quote]

Did you increase the characteristic length (.max_len)?

Please see Step 2.H, Set characteristic length in the Bluetooth low energy Characteristics, a beginner's tutorial.

The latest question seems it's not related to the subject.

If you have any new questions, please create a new support case. It will be easy for other users to search on the Devzon.

RE: How to change the default MTU size of the BLE central (ble_app_blinky_c)?

Dhyanes — Tue, 22 Oct 2019 08:29:36 GMT

Hi Turbo,

I could update the RAM settings, thank you for the answer. But still the central is not able to send more than 20 bytes while writing for a characteristic and I get an invalid data size error as a return statement. Do you have an idea on how to solve this issue? Advance thank you.

RE: How to change the default MTU size of the BLE central (ble_app_blinky_c)?

Dhyanes — Mon, 21 Oct 2019 15:27:44 GMT

Hi Turbo

Thank you for the answers. I am currently using Segger Embedded studio for code compilation and generating hex files. I could open the linker settings of my project but I am not able to see any RAM related settings. Can you throw some light over the same? please

Regards

Dhyanes

RE: How to change the default MTU size of the BLE central (ble_app_blinky_c)?

Turbo J — Mon, 21 Oct 2019 15:22:30 GMT

Expected behaviour: You have to change the linker settings in order to fullfill the softdevices larger RAM requirements. Check your linker script, and also check the log messages - it should tell you how what RAM setting would be required.