Set "write-with(out)-response" flag

[daten]

Hello,

I'm stuck with a seemingly simple issue: I fail to find the place where to set the flag indicating the peripheral unit supports (only) write-with-response or write-without-response.

No matter what I tried so far, the peripheral - nrf51 and nrf52 units - always have the "write-without-response"-flag set in their advertisements.

I'd really appreciate a pointer where to change "write-without-response" to "write-with-response" using latest SDKs for nrf51 as well as nrf52.

In case it's important: I'm advertising UART services.

Thanks a lot!

[tesc]

Hi,

I am afraid I do not understand what you are looking for. I am not aware of any such flags for advertising. The closest I can think of is permission settings in the ATT table, used e.g. for GATT Services and Characteristics, where you set e.g. whether a characteristic can be read, written, etc. There is however no distinction there on what write procedures are supported or not supported.

Can you explain some more what you are looking for?

Regards,
Terje

[daten]

Hey, thanks for your fast answer (really appreciated!) and sorry for not having been clear.

Let me try to elaborate: I'm talking about the "write with response" / "write without/no response" flag on the characteristic service advertisement.

When using the app "nrf connect", selecting a peripheral, then selecting a service (in my case nordic UART service) I can see that it states under:

Nordic UART service

  RX Charactertistic

    Properties: WRITE, WRITE NO RESPONSE

I'd like *not* to have "WRITE NO RESPONSE" being advertised.

[tesc]

Hi,

Thank you for the elaboration. The confusion was because of "advertising" being a specific concept in BLE, and this is not part of that concept.

What you see in the nRF Connect application is what procedures (read, write, etc.) are possible on the characteristic. It is a result from what is stored in the attribute table on the device. It is something nRF Connect finds out during "Database Discovery", where it essentially reads the full GATT table from the device.

The way to change those settings, is when the characteristics are added to the device with sd_ble_gatts_characteristic_add(). The p_char_md argument, a structure of type ble_gatts_char_md_t, has a field char_props of type ble_gatt_char_props_t, where which procedures should be possible are set.

Please note however that other implementations of the Nordic UART service may rely on using WRITE NO RESPONSE, and so may not work properly with your device if you remove the WRITE NO RESPONSE. It should not be an issue if you control both ends, and/or if you change Service and Characteristic UUIDs to your own.

Regards,
Terje