Service Notification problem - BLE_ERROR_INVALID_ATTR_HANDLE

[GT]

Hello everyone,

I am trying to enable notification on a characteristic based on the code example from nAN36. Unfortunately the sd_ble_gatts_hvx() function returns:

BLE_ERROR_INVALID_ATTR_HANDLE - "Invalid attribute handle(s) supplied. Only attributes added directly by the application are available to notify and indicate."

I can't quite get the meaning of the "attributes added directly by the application". Any ideas how to interpret that or general guidelines how to approach this problem?

The setup is: ARMGCC + S110 + 51822. I am testing it with the nRF Master Control Panel, where it says that the notifications are enabled.

Thank you in advance!

[Petter Myhre]

Services, characteristics and descriptors are attributes. You add them by with

sd_ble_gatts_service_add() sd_ble_gatts_characteristic_add() sd_ble_gatts_descriptor_add()

These return the attribute handles that are use in the attribute table.

So when you call sd_ble_gatts_hvx() you need to ensure that you use the correct attribute handle of the characteristic value that you want to send a notifcation from.

[GT]

Hello Petter, Thank you for the answer. However I am still having troubles with BLE_ERROR_INVALID_ATTR_HANDLE when I try to check if the notify/indicate is enabled.

This is how the characteristic is added to the service:

	    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;

    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;

    ble_uuid.type = p_lbs->uuid_type;
    ble_uuid.uuid = LBS_UUID_BUTTON_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_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;

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

This is what happens whne the button gets pressed:

uint32_t err_code;
ble_gatts_hvx_params_t params;
uint16_t len = sizeof(button_state);

memset(&params, 0, sizeof(params));
params.type = BLE_GATT_HVX_NOTIFICATION;
params.handle = p_lbs->button_char_handles.value_handle;
params.p_data = &button_state;
params.p_len = &len;

err_code = sd_ble_gatts_hvx(p_lbs->conn_handle, &params);

Is it correct to add "button_char_handles" and later try to notify on "params.handle = p_lbs->button_char_handles.value_handle"?

Any input will be highly appreciated. Thanks!

[Petter Myhre]

This is not an answer. You should have edited your question to include the information. Anyways, your code looks correct. Are you able to use the debugger to see what parameters are sent to sd_ble_gatts_hvx()? The error code you are getting is 0x00003003 right? Are you aware of this? It is the lbs code working with SDK 8.0.0

[GT]

Thanks for the help. The problem turned out to be not proper handling of the characteristic handles form my side...