Nordic UART Service Descriptors?

[rvaessen]

I have written an iOS application that is connecting to the BLE UART example (...\nRF51_SDK_9.0.0_2e23562\examples\ble_peripheral\ble_app_uart) running on an nRF51 DK. I am also using the MCP to connect to the nus via an nRF51 Dongle. I am comparing the information that my iOS app discovers with the information displayed by the MCP. The MCP is showing me information that I have not yet been able to discover with the iOS app. In particular: the service name "UART over BLE" and the characteristic names "UART TX" and "UART RX" - see the screen shot below. I have searched all of the SDK 9 files for these three names and have only found them in documentation and comments, not in source code. This has led me to conjecture that the MCP itself is mapping the nus UUIDs to these names. Would someone please help me to understand this? In particular: are these names being transmitted to the MCP by the nus via BLE?

[Eric Stutzenberger]

They must be doing this in the MCP program itself. From the tx_char_add function in ble_nus.c:

char_md.char_props.write         = 1;
char_md.char_props.write_wo_resp = 1;
char_md.p_char_user_desc         = NULL;
char_md.p_char_pf                = NULL;
char_md.p_user_desc_md           = NULL;
char_md.p_cccd_md                = NULL;
char_md.p_sccd_md                = NULL;

For those fields to be available from the device itself, p_user_desc would have to be set to some value other than NULL. If it was, then you could find in using the iOS APIs.

HTH,

Eric

[rvaessen]

Thank you, Eric.

After seeing your answer, I set p_user_desc to "Hello" in ble_nus.c. Doing this has caused the following new information to be displayed by the MCP:

 CharacteristicUserDescription, Value:48-65-6C-6C-6F,-00, UserDescription: Hello

However, on the iOS side I am not detecting any new descriptors for the characteristic.

Do you have any thoughts on this?

[Eric Stutzenberger]

Hmm. I'm not sure. Try refreshing the iOS BT server by turning Bluetooth On and Off. You can keep iOS from caching the BT server info by setting IS_SRVC_CHANGED_CHARACT_PRESENT to 1 instead of 0. This will inform any Central that connects that data might change. Note that caching is preferred but during development it can cause issues such as these.

[rvaessen]

U da man! Thanks bunches :-)