Adding Characteristic User Description 0x2901,0x2902

[Milan]

Hi Team,

I am trying to implement Blugiga's cable replacement service in Nordic chip. I have successfully changed required UUIDs for services and characteristics please refer it here

Now unable to do following:

1. Adding Characteristic User Description 0x2901,0x2902

2. I need to maintain backward compatibility with current Mobile Application which communicates with bluegiga using following:

Mobile App to Blugiga Opcode: Write Request (0x12) Handle: 0x000a Value: 0200

Opcode: Prepare Write Request (0x16) Offset: 0 Value:38a3cf34fb27d83b8e58db

Blugiga to Mobile App Opcode: Handle Value Indication (0x1d) Handle: 0x0008 Value:010203031

I am modifying ble_uart application which uses different handles and commands to communicate with nordic's uart mobile application.

What to do so that I can make non-nordic Mobile application to work with Nordic soc.

Please help!!!

Regards, Milan

[Ulrich Myhre]

Are you depending on hard-coded handles or will the peer device do a proper discovery? Handles are given out sequentially, so it is not possible to guarantee that every declaration will be given the same handle as the device you are copying.

Please also list how you are unable to add user description fields. How are you trying to do it, and what return codes do you see?

[Milan]

I don't have any information regarding peer device is doing proper discovery or not.
Only available information is Mobile app and Blugiga device using some propriety service called cable replacement and I am trying to achieve same in nordic soc by modifying ble_uart app.

I don't have idea how to add 0x2901 descriptor. Using Nordic's Master Control android app shows 0x2902 descriptor and I need to add 0x2901.

[Ulrich Myhre]

First of all, here is a reference explaining what the adopted UUIDs mean: developer.bluetooth.org/.../DescriptorsHomePage.aspx. You are lacking a User Description and a CCCD for your characteristic.

To add a user description, see here: developer.nordicsemi.com/.../a00283.html. The p_user_desc_md must be pointing to a proper ble_gatts_attr_md_t. This is very close to how you add a CCCD, so you can look in other examples how that is done. Also set char_ext_props.wr_aux to 1 if it is writable.

Simply add a CCCD to add the UUID 0x2902 descriptor.

[Milan]

Hi! I need to add 0x2901 and not 0x2902. was it typo?

[Ulrich Myhre]

Please read the document I linked. 0x2901 is Characteristic User Description. 0x2902 is Client Characteristic Configuration.