How to add characteristic user description?

RE: How to add characteristic user description?

Vidar Berg — Mon, 09 Nov 2020 11:22:49 GMT

Thanks for confirming that it worked!

Best regards,

Vidar

RE: How to add characteristic user description?

June6 — Mon, 09 Nov 2020 10:40:15 GMT

Thank you for helping me a lot. Everything is OK!

Best regards,

June6

RE: How to add characteristic user description?

Vidar Berg — Mon, 09 Nov 2020 10:21:55 GMT

Hi,

I didn't know this, but you have to set the wr_aux bit in order to allow the user descriptor to be written to. I get the same error as you otherwise.

Best regards,

Vidar

RE: How to add characteristic user description?

June6 — Mon, 09 Nov 2020 03:08:55 GMT

Hi，

Yes, maybe it's the null pointer problem, because I found through debugging that the parameters there are indeed null. However, after I add your suggested code, I will receive an error (NRF_ERROR_INVALID_PARAM) when I perform the characteristic_add operation

Best regards,

June6

RE: How to add characteristic user description?

Vidar Berg — Fri, 06 Nov 2020 14:10:53 GMT

Hello,

p_user_descr is a NULL pointer in your case. Please try to set it up like this instead:

    ble_add_char_user_desc_t  user_desc;

    uint8_t user_desc_str[] = "DFU";

    memset(&user_desc, 0, sizeof(user_desc));
    user_desc.is_var_len       = 1;
    user_desc.char_props.read  = 1;
    user_desc.size             = (sizeof(user_desc_str) - 1); // Don't include null termination
    user_desc.max_size         = (sizeof(user_desc_str) - 1); // Don't include null termination
    user_desc.p_char_user_desc = user_desc_str;
    user_desc.read_access      = SEC_OPEN;
    user_desc.write_access     = SEC_OPEN;
    
    memset(&add_char_params, 0, sizeof(add_char_params));
    add_char_params.p_user_descr = &user_desc;
    ...

Best regards,

Vidar