nRF connect desktop app - update MTU field disabled

RE: nRF connect desktop app - update MTU field disabled

Amanda Hsieh — Fri, 24 Jan 2025 14:27:59 GMT

See the answer in this post.

RE: nRF connect desktop app - update MTU field disabled

VinuGopalakrishnan — Fri, 24 Jan 2025 10:40:14 GMT

Amanda,

Thanks for the reply. It seems the tool does not support MTU size greater than 247 ? Our code used L2CAP MTU size of 498. When we set the size to 247, data transmission works. See the log below :

regards,

Vinu

RE: nRF connect desktop app - update MTU field disabled

Amanda Hsieh — Wed, 22 Jan 2025 19:29:02 GMT

Could you test with the https://github.com/NordicDeveloperAcademy/bt-fund/tree/main/v2.6.2-v2.3.0/l3/l3_e2_sol? It will update MTU to 247 once connecting. Then, you could not update MTU from the nRF BLE app because it's already done.

Here is my test project devzone.nordicsemi.com/.../peripheral_5F00_uart_5F00_updateL.7z for NCS v2.6.1. You can update MTU after connecting. After you update MTU from the nRF BLE app, the function will be disabled.

Hope the above examples can help you.

RE: nRF connect desktop app - update MTU field disabled

VinuGopalakrishnan — Wed, 22 Jan 2025 10:04:11 GMT

Yes, we are doing the same.

RE: nRF connect desktop app - update MTU field disabled

Amanda Hsieh — Tue, 21 Jan 2025 21:12:49 GMT

Do you also update configs in child_image/hci_ipc.conf as Step. 12?

CONFIG_BT_USER_DATA_LEN_UPDATE=y
CONFIG_BT_BUF_ACL_RX_SIZE=251
CONFIG_BT_BUF_ACL_TX_SIZE=251
CONFIG_BT_L2CAP_TX_MTU=247

RE: nRF connect desktop app - update MTU field disabled

VinuGopalakrishnan — Sat, 18 Jan 2025 07:54:34 GMT

We are using NCS v2.6.1. Yes, the connection parameter update requests are sent from the peripheral. see below snippet:

	/*update connection interval*/
	update_connection_parameters(my_conn);
	/* update the PHY mode */
	update_phy(my_conn);
	/* update the data length*/
	update_data_length(my_conn);
	/* update MTU size*/
	update_mtu(my_conn);

RE: nRF connect desktop app - update MTU field disabled

Amanda Hsieh — Fri, 17 Jan 2025 21:16:27 GMT

Hi,

What NCS version are you using?

From your first figure seems that you have updated the MTU. You can check the log of the nRF BLE app for the MTU size.

To increase the MTU properly, I suggest you check out the Bluetooth Low Energy Fundamentals course at Nordic Developer Academy. Particularly Lesson 3 Exercise 2, Step. 10 and 11 are relevant. Give it a go, and let me know if you are still stuck.

Regards,
Amanda H.