Sending consecutive BLE notifications

RE: Sending consecutive BLE notifications

Jørgen Holmefjord — Fri, 25 Jan 2019 15:12:29 GMT

It would be helpful if you could provide a sniffer trace of the connection, to know if the issue is on the nRF side or on the phone side.

RE: Sending consecutive BLE notifications

IstvanS — Fri, 25 Jan 2019 08:30:43 GMT

Fyi, I've decided to change the characteristic to send all data in one packet (6 data bytes + 2 bytes overhead). This should not be a problem then. However, it's still interesting why it doesn't work without the delay.

RE: Sending consecutive BLE notifications

IstvanS — Fri, 25 Jan 2019 06:40:11 GMT

Without the delay, phone gets the last notification/data (i.e. data[0] = 3; data[1] = sensor_data[2]) 3 times.

RE: Sending consecutive BLE notifications

Jørgen Holmefjord — Thu, 24 Jan 2019 15:10:19 GMT

Ok, that looks correct. Is it the first or the last data you are receiving if you do not put the delay?

RE: Sending consecutive BLE notifications

IstvanS — Thu, 24 Jan 2019 07:23:24 GMT

This is ble_send():

uint32_t ble_send(uint16_t conn_handle, ble_abc_t * p_abc, uint8_t * data)
{
	ble_gatts_hvx_params_t params;
	uint16_t len = 4;

    memset(&params, 0, sizeof(params));
    params.type   = BLE_GATT_HVX_NOTIFICATION;
    params.handle = p_ams->config_char_handles.value_handle;
    params.p_data = data;
    params.p_len  = &len;

    return sd_ble_gatts_hvx(conn_handle, &params);
}

This is the function where notifications are sent:

void sendDataControl(void)
{
	ret_code_t err_code;
	
	if(isDataReady)
	{
        uint16_t data[2];

        for (uint8_t i = 0; i < 3; i++)
        {
	        data[0] = i+1;
	        data[1] = u16_sensor_data[i]; // copy data from global array
			
	        err_code = ble_send(m_conn_handle, &m_abc, (uint8_t*)&data);
	        while (err_code != NRF_SUCCESS); // wait for NRF_SUCCESS
	        nrf_delay_ms(100); // with delay, phone app gets all data correctly
			                   // without delay, phone app gets the lastly sent data 3 times
	        if (err_code != NRF_SUCCESS &&
	        err_code != BLE_ERROR_INVALID_CONN_HANDLE &&
	        err_code != NRF_ERROR_INVALID_STATE &&
	        err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
	        {
		        APP_ERROR_CHECK(err_code);
	        }
        }
        
        isDataReady = false;
    }
}

RE: Sending consecutive BLE notifications

Jørgen Holmefjord — Wed, 23 Jan 2019 12:08:42 GMT

Can you post the code of ble_send()? How is data updated between calls to ble_send() in the loop?