Enabling BLE notifications from code doesn't work.

[EdHa_4455331]

I am trying to enable BLE notifications for a parameter from code (instead of from a paired client). I have read through some other posts on this topic and it seems like I'm doing what is needed to do this. Here is my code:

void SetPulseLevel( uint8_t newLevel )
{
cy_stc_ble_gatt_handle_value_pair_t gattHandle;
uint8 notificationEnable[1];
cy_en_ble_api_result_t status;
cy_en_ble_gatt_err_code_t ret;

UNUSED( status );
UNUSED( ret );

// Force notifications to be enabled for this characteristic.
notificationEnable[0] = 1;
gattHandle.attrHandle = CY_BLE_POC_SETTINGS_PULSE_LEVEL_CHAR_HANDLE;
gattHandle.value.len = 1;
gattHandle.value.val = notificationEnable;
ret = Cy_BLE_GATTS_WriteAttributeValuePeer( &appConnHandle, &gattHandle );

// Push out a BLE notification.
gattHandle.attrHandle = CY_BLE_POC_SETTINGS_PULSE_LEVEL_CHAR_HANDLE;
gattHandle.value.len = sizeof( newLevel );
gattHandle.value.val = &newLevel;
status = Cy_BLE_GATTS_SendNotification( &appConnHandle, &gattHandle );

}

ret is CY_BLE_GATT_ERR_NONE (which sounds right), but status is always CY_BLE_ERROR_NTF_DISABLED.

And I do have notifications enabled in the BLE GUI:

Any help will be gratefully appreciated.

Thanks,

Ed H.

[Yugandhar]

Hello,

Client is responsible to change CCCD state and it is not recommended to enable the notifications at server side. If you need for some specific reason to do this, you can use Cy_BLE_GATTS_WriteAttributeValueCCCD() api for doing this.
Please refer to the below code.

*******************************************************************************************************
cy_stc_ble_gatt_handle_value_pair_t handle_value;
uint8 notificationEnable[1];

notificationEnable[0] = 1;
handle_value.attrHandle = CY_BLE_DRO_XAXIS_CLIENT_CHARACTERISTIC_CONFIGURATION_DESC_HANDLE;
handle_value.value.len = 1;
handle_value.value.val = notificationEnable;

cy_stc_ble_gatts_db_attr_val_info_t dbAttrVal =
{
.handleValuePair = handle_value,
.connHandle = cy_ble_connHandle[0],
.flags = CY_BLE_GATT_DB_LOCALLY_INITIATED,
.offset = 0u
};

gatt_error = Cy_BLE_GATTS_WriteAttributeValueCCCD(&dbAttrVal);

*******************************************************************************************************

Thanks,
P Yugandhar.

[EdHa_4455331]

My auto-generated code for the characteristic I need to enable does not define a  _DESC_ constant for that characteristic. Did you mean _DECL_?

Thanks, 

Ed H.

[Yugandhar]

Hello,

You will get an attribute handle for your Client Characteristic Configuration descriptor. In PSoC Creator, Go to Generated source-> PSoC6-> BLE-> BLE_Config.h file you can find the list of attribute handles of the defined Custom Services and their characteristics.

Thanks,
P Yugandhar.

[EdHa_4455331 · Accepted solution]

My bad. I bungled the search for _DESC_ defines last time. You solution did the trick.

Very grateful,

Ed H.