I have enabled notification but still gets a 0x3401 error?

[Mitch996]

Hello, when using sd_ble_gatts_hvx(), I keep getting 0x3401 error. I googled it and it appears that it's because I might not have the notification enabled.

But I very much did. The MCP showed me this:

And the code on my android device also did enable notification:

if ((charaProp | BluetoothGattCharacteristic.PROPERTY_NOTIFY) > 0) {
                        mNotifyCharacteristic = characteristic;
                        mBluetoothLeService.setCharacteristicNotification(
                                characteristic, true);

Also, here's my config for that characteristic, when trying to add the characteristic:

static uint32_t mesh_value_char_add(void)
{
/* BLE GATT metadata */
ble_gatts_char_md_t ble_char_md;

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


ble_char_md.char_props.write_wo_resp = 1;
ble_char_md.char_props.notify = 1;
ble_char_md.char_props.read = 1;//*
ble_char_md.char_props.write =1;//*


ble_char_md.p_cccd_md = NULL;//
ble_char_md.p_sccd_md = NULL;
ble_char_md.p_char_user_desc = NULL;
ble_char_md.p_user_desc_md = NULL;



/* ATT metadata */

ble_gatts_attr_md_t ble_attr_md;

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

/* No security is required */
ble_attr_md.write_perm.lv = 1;
ble_attr_md.write_perm.sm = 1;

BLE_GAP_CONN_SEC_MODE_SET_OPEN(&ble_attr_md.read_perm); //*
BLE_GAP_CONN_SEC_MODE_SET_OPEN(&ble_attr_md.write_perm);//* 

ble_char_md.p_cccd_md = &ble_attr_md;//*
ble_char_md.char_props.notify   = 1;//*

ble_attr_md.vloc = BLE_GATTS_VLOC_STACK;
ble_attr_md.rd_auth = 1;
ble_attr_md.wr_auth = 1;
ble_attr_md.vlen = 1;


/* ble characteristic UUID */
ble_uuid_t ble_uuid;

ble_uuid.type = m_mesh_base_uuid_type;
ble_uuid.uuid = MESH_VALUE_CHAR_UUID;

/* ble attribute */
ble_gatts_attr_t ble_attr;
uint8_t default_value = 0;

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

ble_attr.init_len = 1;
ble_attr.init_offs = 0;
ble_attr.max_len = sizeof(mesh_gatt_evt_t);
ble_attr.p_attr_md = &ble_attr_md;
ble_attr.p_uuid = &ble_uuid;
ble_attr.p_value = &default_value;

/* add to service */
uint32_t error_code = sd_ble_gatts_characteristic_add(
        m_mesh_service.service_handle,
        &ble_char_md,
        &ble_attr,
        &m_mesh_service.ble_val_char_handles);

if (error_code != NRF_SUCCESS)
{
    return NRF_ERROR_INTERNAL;
}

return NRF_SUCCESS;
}

So... what did I do wrong?

[RK]

0x3401 isn't about enabling notifications, it's the error you get when you haven't set the system attribute, so set it. Typing 0x3401 into the search box at the top will give you a half dozen threads, many of them solved.

[Mitch996]

Can you shed some more light on this " system attribute"? Is it one of the 2 default attribute that one must have in a GATT connection?

[Petter Myhre]

You don't have to google to figure out what the error code means. BLE_ERROR_GATTS_SYS_ATTR_MISSING is one of the possible error codes returned by sd_ble_gatts_hvx(), see its documentation. If you the examine how BLE_ERROR_GATTS_SYS_ATTR_MISSING is defined you will see that it is 0x3401.

See this answer and this MSC for how to handle it. And this for some more information.