Sending data

[mohBOSS]

Hi all,

I have a small question. If a GATT server needs to send data to a GATT client(about 65 bytes), does it have to create a service first and then adds characteristic, or it can use directly sd_gap_gatts_hvx function()?

Regards,

mohBOSS.

[Carles]

Hi there,

You will need to add a service and a characteristic to send arbitrary data. Once you have the handle to the characteristic you can use sd_ble_gatts_hvx() to send data. Alternatively, if it's easier for you, you can add the service and characteristic on the peer device and use sd_ble_gattc_write() to send data, acting as a GATT client.

Carles

[mohBOSS]

Hi Carles,

In fact I need to be a server, in order to send data to the client. I can not understand yet how to make a service that can be used by the client to read data. So far I have adapted this code for my needs.

static uint32_t characteristic_add(ble_lbs_t * p_lbs) { ble_gatts_char_md_t char_md; ble_gatts_attr_t attr_char_value; ble_uuid_t ble_uuid; ble_gatts_attr_md_t attr_md;

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

char_md.char_props.read   = 1;
char_md.char_props.write  = 1;
char_md.char_ext_props.reliable_wr = 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;

ble_uuid.type = p_lbs->uuid_type;
ble_uuid.uuid = LBS_UUID_LED_CHAR;

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

BLE_GAP_CONN_SEC_MODE_SET_OPEN(&attr_md.read_perm);
BLE_GAP_CONN_SEC_MODE_SET_OPEN(&attr_md.write_perm);

attr_md.vloc       = BLE_GATTS_VLOC_STACK;
attr_md.rd_auth    = 0;
attr_md.wr_auth    = 0;
attr_md.vlen       = 1;

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      = 30;
attr_char_value.p_value      = NULL;

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

}

But I can't replace the ble_lbs_t type with what I need.

I hope You are understanding me Dear Carles.