UART Bridge between Central and Peirpheral

[enkavak]

Hello,

        I want to make a simple UART Bridge between Central and Peirpheral. I'm usign nRF52832 with nRF5_SDK v15. There are central and peripheral uart examples in the SDK. 

        I can connect to any mobile phone by peripheral example. However I can not work with the central example.

        How can I connect to a peripheral device by using central example ? How will I select the device to connect ? do I need to write a static MAC address or UUID ?

        When I run the central example, I just see the string on the uart line. "BLE UART central example started."

  

Best Regards  

[Vidar Berg]

Hello,

The NUS service UUID is defined in ble_nus_c.h (NUS_BASE_UUID + BLE_UUID_NUS_SERVICE)

"In case there are two BLE devices nearby, Which one is selected by the central to connect ?How can I connect the one that I want to. In short, I just want to seach for the specific UUID devices nearby, and then I will select one of them to connect."

The central example will connect to the first device it sees, and the decision to connect is made in main.c::on_adv_report(). So the on_adv_report() needs to be modified if you want to connect to a device based on user input. You could use the UART interface to display discovered devices and receive user input. 

[enkavak]

Hello

      As I see from the code in the function on_adv_report() it connect to peripheral. However I can not understand How should be the code structure in order to establish a specifically selected peripheral BLE device. 

p_adv_report->peer_addr.addr keeps the address of the peripheral device. 

ble_advdata_uuid_find() this function is called one time. if it finds a connectible device, it connect. never called again.

How can I list the nearby devices? I do not want to connect at first found device. 

[enkavak]

I have modified the on_adv_report() function. Now it prints all BLE devices nearby.

When I feed the selected BLE device addres to array p_adv_report->peer_addr, will it connect to that device ?

static void on_adv_report(ble_gap_evt_adv_report_t const * p_adv_report)
{
    ret_code_t err_code;

    if (ble_advdata_uuid_find(p_adv_report->data.p_data, p_adv_report->data.len, &m_nus_uuid))
    {
        //err_code = sd_ble_gap_connect(&p_adv_report->peer_addr,
        //                              &m_scan_params,
        //                              &m_connection_param,
        //                              APP_BLE_CONN_CFG_TAG);

        //if (err_code == NRF_SUCCESS)
        {
            // scan is automatically stopped by the connect
            err_code = bsp_indication_set(BSP_INDICATE_IDLE);
            APP_ERROR_CHECK(err_code);
            //NRF_LOG_INFO("Connecting to target %02x%02x%02x%02x%02x%02x",
            NRF_LOG_INFO("%02x:%02x:%02x:%02x:%02x:%02x",
                     p_adv_report->peer_addr.addr[0],
                     p_adv_report->peer_addr.addr[1],
                     p_adv_report->peer_addr.addr[2],
                     p_adv_report->peer_addr.addr[3],
                     p_adv_report->peer_addr.addr[4],
                     p_adv_report->peer_addr.addr[5]
                     );
        }
    }
    else
    {
        
    }

    err_code = sd_ble_gap_scan_start(NULL, &m_scan_buffer);
    APP_ERROR_CHECK(err_code);
}

[Vidar Berg]

Hello,

Correct, sd_ble_gap_connect() will connect to the device that has the address you provide. Note that ongoing scanning is not stopped if you don't connect, so sd_ble_gap_scan_start() may return NRF_ERROR_INVALID_STATE.