Unable to allocate ATT TX meta

[kfcube]

Hi,

custom board with 52832 and st lsm6dsr sensor. Notify data 100 times / second. 

Occasionally I got this warning:

[00:00:10.303,985] <wrn> bt_att: Unable to allocate ATT TX meta

[00:00:10.303,985] <wrn> bt_gatt: No buffer available to send notification

Which configuration should I increase? Following are my current config, I'd like to know which one is the right one to change.

CONFIG_BT_BUF_ACL_TX_COUNT=5
CONFIG_BT_L2CAP_TX_BUF_COUNT=10
CONFIG_BT_BUF_ACL_TX_SIZE=39
CONFIG_BT_CTLR_DATA_LENGTH_MAX=39

Also, how to make the log in nrfx_twi.c file show? I changed the default level to 3 but couldn't see any logs:
CONFIG_LOG_DEFAULT_LEVEL=3
CONFIG_UART_CONSOLE=y
CONFIG_SERIAL=y
CONFIG_LOG=y
CONFIG_LOG_BACKEND_UART=y

Thanks,

[Susheel Nuguru]

Can you help me reproduce this error?

Can you attach your project here?

[kfcube]

Susheel,

Thanks for your reply. Sorry I can't attach my project but I can tell you what I did. I read sensor data(24 bytes including acce and gyro 6 float numbers) using timer with 100 times / second and notify the mobile app through ble. Sometime I got -12 error (not enough core) then I opened log and found those two warnings. 

All I want to know, is which configuration is for the ATT Tx meta buffer? There are so many configuration items. 

Also, is there anything wrong with my configuration above? Actually I tried a lot of time by increasing one by one. Initially there are lots of -12 and now only several in a minute.

Thanks,
Dragon Ji

[Susheel Nuguru]

What is the size of the sensor data you send per event? I think the DATA_LENGTH_MAX can be bigger. Check if you can calibrate some of the configs as compared to the throughput sample where we have configured parameters to send data as fast as possible.

[kfcube]

Hi Susheel, the size is 24 bytes per event. I will check the sample. Thanks a lot.