BLE stream communication LOG errs

[Sam-IIT]

Hi all,

I've been developing a BLE application on my laptop to communicate with the 52840. I manage to understand how to create and run a BLE connection through the really nice tutorial that has been posted a couple of years ago on youtube.
https://www.youtube.com/watch?v=hY_tDext6zA 

Maybe this is nothing or maybe I'm using the system wrong, but I created a specific characteristic for stream data. Whenever I activate it, my terminal gets flooded with the messages in the attached pic.

My question is, are those only related to the Loggin framework and I should not be (at a certain level) worried? is this an issue about streaming too fast? If the latter, maybe this BLE is not indicated for data streams?

thank you all

[EDIT]

some extra info that may be of use.
I am streaming data out from a worker that runs at 1ms and sends a single uint16 packet over a dedicated characteristic. This error occurs when I enable such stream. Writing/reading single characteristics with manual inputs (using the evk buttons) does not give any issues. Ideally I'd like to stream an array of 16 uint16 elements.

This is my current configuration file

CONFIG_GPIO=y
CONFIG_SPI=y
CONFIG_FPU=y
CONFIG_NEWLIB_LIBC=y
CONFIG_CBPRINTF_FP_SUPPORT=y

# Set CONFIG_NEWLIB_LIBC_FLOAT_PRINTF if printf should be able to print float
CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y

# Enable DK LED and Buttons library
CONFIG_DK_LIBRARY=y

# Configure logger
CONFIG_LOG=y
CONFIG_LOG_MODE_MINIMAL=n
CONFIG_USE_SEGGER_RTT=n
CONFIG_LOG_BACKEND_RTT=n
CONFIG_LOG_BACKEND_UART=y
CONFIG_LOG_DEFAULT_LEVEL=3
CONFIG_LOG_PRINTK=y
CONFIG_LOG_MODE_DEFERRED=y

# Configure Bluetooth
CONFIG_BT=y
CONFIG_BT_PERIPHERAL=y
CONFIG_BT_DEVICE_NAME="XYZ"
CONFIG_BT_DEVICE_APPEARANCE=0
CONFIG_BT_MAX_CONN=1
CONFIG_BT_LL_SOFTDEVICE=y

CONFIG_ASSERT=y

[Sigurd]

Hi!

You could try to increase some BLE related buffers.

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_CTLR_PHY_2M=y

[Sam-IIT]

Hi Sigurd,

thanks for the reply. Unfortunately that had no effect, I still have missing data.

[Sigurd]

1) What SDK version are you using?

2) What BLE connection interval are you using?

I am streaming data out from a worker that runs at 1ms and sends a single uint16 packet

3) Just for testing, if you send it at e.g. 200ms instead, do you see the same issue then?

4) For the logs dropped, could you try to increase CONFIG_LOG_BUFFER_SIZE to e.g. 4096?

[Sam-IIT]

I'm using SDK 2.9. I even implemented the full array of 16 uin16_t to be streamed and I have no issues at 200ms. Even at 50ms works fine, but I am unable to reach 1ms.

Incrementing the log buffer didn't change anything in the output and the log prints report the same error.

How can I change the BLE connection interval? 

[Sam-IIT]

I found the setting CONFIG_BT_CTLR_SDC_MAX_CONN_EVENT_LEN_DEFAULT from other nRF samples.

Since I was not using it, it should have been set to the default of 7.5 ms. I tried to set it to its lower value (2500) but nothing changed.

 

[Sigurd]

Could you post some code snippets that shows how you send your data?