Unable to Increase ACL Packet Size in HCI_USB Sample in nRF Connect SDK

RE: Unable to Increase ACL Packet Size in HCI_USB Sample in nRF Connect SDK

Sigurd — Tue, 10 Dec 2024 15:44:05 GMT

[quote user="AhmedPs19"]I am using nRF Connect SDK 2.6 and it is not recognizing CONFIG_BT_ATT_TX_COUNT[/quote]

It was changed in later releases.

In 2.6 it's called CONFIG_BT_L2CAP_TX_BUF_COUNT.

If it's still not working, could you provide a sniffer trace for the ATT MTU exchange ?

https://www.nordicsemi.com/Products/Development-tools/nRF-Sniffer-for-Bluetooth-LE

RE: Unable to Increase ACL Packet Size in HCI_USB Sample in nRF Connect SDK

AhmedPs19 — Tue, 10 Dec 2024 13:35:53 GMT

Hi Sigurd,

I am using nRF Connect SDK 2.6 and it is not recognizing CONFIG_BT_ATT_TX_COUNT as a valid configuration parameter. Apart from this one , I have added other configurations and it has increased the ACL.

Can you suggest what is the maximum stable MTU size for this sample ?

Regards,
Ahmed

RE: Unable to Increase ACL Packet Size in HCI_USB Sample in nRF Connect SDK

Sigurd — Fri, 06 Dec 2024 12:38:37 GMT

Hi!

Try adding this in prj.conf:

CONFIG_BT_BUF_ACL_RX_SIZE=502
CONFIG_BT_ATT_PREPARE_COUNT=2
CONFIG_BT_ATT_TX_COUNT=10
CONFIG_BT_L2CAP_TX_MTU=498
CONFIG_BT_L2CAP_DYNAMIC_CHANNEL=y
CONFIG_BT_CONN_TX_MAX=10
CONFIG_BT_BUF_ACL_TX_COUNT=10
CONFIG_BT_BUF_ACL_TX_SIZE=502

CONFIG_BT_CTLR_DATA_LENGTH_MAX=251
CONFIG_BT_USER_DATA_LEN_UPDATE=y

Also, if you have issues with hci_usb, then you could try compiling hci_uart with the CDC uart driver and use that instead.