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  • Case ID: 112246
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custom 128 bit uuid characteristic not based on the service uuid

Cincheza Ovidiu

Hi,

I have some similar problem when trying to add the custom 128bit characteristic UUID. The service UUID is advertised correctly but the characteristic UUID not.

I add the Service like this

#define MIDI_SERVICE_UUID {0x00,0xC7,0xC4,0x4E,0xE3,0x6C,0x51,0xA7,0x33,0x4B,0xE8,0xED,0x5A,0x0E,0xB8,0x03}
ble_uuid_t ble_uuid;

// Initialize service structure
p_lbs->conn_handle       = BLE_CONN_HANDLE_INVALID;
p_lbs->led_write_handler = p_lbs_init->led_write_handler;

// Add service
ble_uuid128_t base_uuid = {MIDI_SERVICE_UUID};
err_code = sd_ble_uuid_vs_add(&base_uuid, &p_lbs->uuid_type);
if (err_code != NRF_SUCCESS)
{
    return err_code;
}

sd_ble_uuid_decode(16, (uint8_t *)&base_uuid, &ble_uuid);

err_code = sd_ble_gatts_service_add(BLE_GATTS_SRVC_TYPE_PRIMARY, &ble_uuid, &p_lbs->service_handle);
if (err_code != NRF_SUCCESS)
{
    return err_code;
}

And the characteristic like this:

#define MIDI_CHAR_IO_UUID {0xF3,0x6B,0x10,0x9D,0x66,0xF2,0xA9,0xA1,0x12,0x41,0x68,0x38,0xDB,0xE5,0x72,0x77}
ble_gatts_char_md_t char_md;
ble_gatts_attr_md_t cccd_md;
ble_gatts_attr_t    attr_char_value;
ble_uuid_t          ble_uuid;
ble_gatts_attr_md_t attr_md;

ble_uuid128_t base_uuid = {MIDI_CHAR_IO_UUID};
 
memset(&cccd_md, 0, sizeof(cccd_md));

BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.read_perm);
BLE_GAP_CONN_SEC_MODE_SET_OPEN(&cccd_md.write_perm);
cccd_md.vloc = BLE_GATTS_VLOC_STACK;

memset(&char_md, 0, sizeof(char_md));

char_md.char_props.read   = 1;
char_md.char_props.notify = 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         = &cccd_md;
char_md.p_sccd_md         = NULL;

sd_ble_uuid_decode(16, (uint8_t *)&base_uuid, &ble_uuid);
	
ble_uuid.type = BLE_UUID_TYPE_VENDOR_BEGIN;

memset(&attr_md, 0, sizeof(attr_md));

BLE_GAP_CONN_SEC_MODE_SET_OPEN(&attr_md.read_perm);
BLE_GAP_CONN_SEC_MODE_SET_NO_ACCESS(&attr_md.write_perm);
attr_md.vloc       = BLE_GATTS_VLOC_STACK;
attr_md.rd_auth    = 0;
attr_md.wr_auth    = 0;
attr_md.vlen       = 0;

memset(&attr_char_value, 0, sizeof(attr_char_value));

attr_char_value.p_uuid       = &ble_uuid;
attr_char_value.p_attr_md    = &attr_md;
attr_char_value.init_len     = sizeof(uint8_t);
attr_char_value.init_offs    = 0;
attr_char_value.max_len      = sizeof(uint8_t);
attr_char_value.p_value      = NULL;

sd_ble_gatts_characteristic_add(p_lbs->service_handle, &char_md,
                                           &attr_char_value,
                                           &p_lbs->button_char_handles);

image description

So what i want to achieve is to add a service with a custom 128bit uuid that has a characteristic with a completely different 128bit uuid (it's not based on the service uuid)

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