How to add an additional characteristic to the NUS service

RE: How to add an additional characteristic to the NUS service

jay — Mon, 10 Dec 2018 17:17:17 GMT

Hi,

Now working fine. Please close the ticket.

Thank you for your help

RE: How to add an additional characteristic to the NUS service

Vidar Berg — Mon, 10 Dec 2018 15:18:25 GMT

Have you tested this, I think it should work, but still think that sd_ble_gatts_value_get() is redundant since you can retrieve the same data from the p_ble_evt->evt.gatts_evt.params.write.data pointer. Please try code below if it doesn't work:

static void on_write(ble_nus_t * p_nus, ble_evt_t * p_ble_evt)
{
    ble_gatts_evt_write_t * p_evt_write = &p_ble_evt->evt.gatts_evt.params.write;
	
    if (
        (p_evt_write->handle == p_nus->rx_handles.cccd_handle)
        &&
        (p_evt_write->len == 2)
       )
    {
        if (ble_srv_is_notification_enabled(p_evt_write->data))
        {
            p_nus->is_notification_enabled = true;
        }
        else
        {
            p_nus->is_notification_enabled = false;
        }
    }
    else if 
		(
        (p_evt_write->handle == p_nus->char_handles1.cccd_handle)
         &&
         p_evt_write->len == 2)
		)
		
			if (ble_srv_is_notification_enabled(p_evt_write->data))
			{
				printf("Notification enabled\r\n");
			}
			else
			{
				printf("Notification disabled\r\n");
			}
	
    else if (
             (p_evt_write->handle == p_nus->tx_handles.value_handle)
             &&
             (p_nus->data_handler != NULL)
            )
    {
        p_nus->data_handler(p_nus, p_evt_write->data, p_evt_write->len);
    }
	else if ( (p_evt_write->handle == p_nus->char_handles1.value_handle) && (p_evt_write->len == 4))
	{
		uint32_t data_buffer0;
		
		memcpy(&data_buffer0, p_evt_write->data, sizeof(uint32_t));
		p_nus->gpio_output_write_handler(p_nus, data_buffer0)
		
	)	
}

RE: How to add an additional characteristic to the NUS service

jay — Mon, 10 Dec 2018 14:27:17 GMT

static void on_write(ble_nus_t * p_nus, ble_evt_t * p_ble_evt)
{
    ble_gatts_evt_write_t * p_evt_write = &p_ble_evt->evt.gatts_evt.params.write;

	
    if (
        (p_evt_write->handle == p_nus->rx_handles.cccd_handle)
        &&
        (p_evt_write->len == 2)
       )
    {
        if (ble_srv_is_notification_enabled(p_evt_write->data))
        {
            p_nus->is_notification_enabled = true;
        }
        else
        {
            p_nus->is_notification_enabled = false;
        }
    }
    else if (
             (p_evt_write->handle == p_nus->tx_handles.value_handle)
             &&
             (p_nus->data_handler != NULL)
            )
    {
        p_nus->data_handler(p_nus, p_evt_write->data, p_evt_write->len);
    }
    else
    {
				// Decclare buffer variable to hold received data. The data can only be 32 bit long.
				uint32_t data_buffer0;
				// Populate ble_gatts_value_t structure to hold received data and metadata.
				ble_gatts_value_t rx_data;
				rx_data.len = sizeof(uint32_t);
				rx_data.offset = 0;
				rx_data.p_value = (uint8_t*)&data_buffer0;
			
                // Check if write event is performed on asi characteristic or the CCCD
				if (p_evt_write->handle == p_nus->char_handles1.value_handle)
				{
					// Get data
					sd_ble_gatts_value_get(p_nus->conn_handle, p_nus->char_handles1.value_handle, &rx_data);
					p_nus->gpio_output_write_handler(p_nus, data_buffer0);
				
				}
				else if((p_evt_write->handle == p_nus->char_handles1.cccd_handle)&&(p_evt_write->len == 2))
				{
					// Get data
					sd_ble_gatts_value_get(p_nus->conn_handle, p_nus->char_handles1.cccd_handle, &rx_data);
					if(data_buffer0 == 0x0001)
					{
            printf("Notification enabled\r\n");
					}
					else if(data_buffer0 == 0x0000)
					{
            printf("Notification disabled\r\n");
					}
				}
    }
}

What about this way? I want to add a separate char under NUS service.

RE: How to add an additional characteristic to the NUS service

Vidar Berg — Mon, 10 Dec 2018 09:59:38 GMT

Hi,

I don't see anything in your code snippet that can cause the program to get stuck. However, you don't need to call sd_ble_gatts_value_get() as the data pointer is provided in p_ble_evt->evt.gatts_evt.params.write.data.

default on_write handler in nordic uart service:

/**@brief Function for handling the @ref BLE_GATTS_EVT_WRITE event from the S110 SoftDevice.
 *
 * @param[in] p_nus     Nordic UART Service structure.
 * @param[in] p_ble_evt Pointer to the event received from BLE stack.
 */
static void on_write(ble_nus_t * p_nus, ble_evt_t * p_ble_evt)
{
    ble_gatts_evt_write_t * p_evt_write = &p_ble_evt->evt.gatts_evt.params.write;

    if (
        (p_evt_write->handle == p_nus->rx_handles.cccd_handle)
        &&
        (p_evt_write->len == 2)
       )
    {
        if (ble_srv_is_notification_enabled(p_evt_write->data))
        {
            p_nus->is_notification_enabled = true;
        }
        else
        {
            p_nus->is_notification_enabled = false;
        }
    }
    else if (
             (p_evt_write->handle == p_nus->tx_handles.value_handle)
             &&
             (p_nus->data_handler != NULL)
            )
    {
        p_nus->data_handler(p_nus, p_evt_write->data, p_evt_write->len); // Notify app through registered callback
    }
    else
    {
        // Do Nothing. This event is not relevant for this service.
    }
}

RE: How to add an additional characteristic to the NUS service

jay — Fri, 07 Dec 2018 14:42:02 GMT

Hi Vidar,

Thank you for your feedback. Yes, you are right. It was the cache clearance issue from mobile phone.

Now I have a new problem related with "sd_ble_gatts_value_get". My code was stuck at it.

if (p_evt_write->handle == p_nus->char_handles1.value_handle)
{

sd_ble_gatts_value_get(p_nus->conn_handle, p_nus->char_handles1.value_handle, &rx_data);
printf("Value received on handle %#06x: %#010x\r\n", p_evt_write->handle, data_buffer0);
p_nus->gpio_output_write_handler(p_nus, data_buffer0);

}

Do you have any suggestion around this issue?

BTW, should I close this and re-open the ticket for this new issue?

Thanks

RE: How to add an additional characteristic to the NUS service

Vidar Berg — Tue, 04 Dec 2018 13:56:07 GMT

Hi,

This may be caused by attribute caching, your code appears to be correct. The phone will cache the attribute table across connections unless the "service changed" characteristic is present. I.e., it will remember the attribute table from before you added the new characteristic. If you have an iphone you can clear the cache by enabling and disabling flight mode.