How to communicate with specific peripheral during multiple peripherals BLE connection with NUS

[laumung]

Hello all. Now I am making a BLE network with multiple peripherals and central based on NUS. How could I make data transfer between the central and specific peripherals? I followed the "ble_app_multilink_central" in the example folder. I made two peripherals which name is "m_target_peripheral_name_1" and "m_target_peripheral_name_2". But the code doesn't work at all. So how can I make connection between specific peripheral and central? Thanks.

static void scan_init(void)
{
    ret_code_t          err_code;
    nrf_ble_scan_init_t init_scan;

    memset(&init_scan, 0, sizeof(init_scan));

    init_scan.connect_if_match = true;
    init_scan.conn_cfg_tag     = APP_BLE_CONN_CFG_TAG;

    err_code = nrf_ble_scan_init(&m_scan, &init_scan, scan_evt_handler);
    APP_ERROR_CHECK(err_code);

    /* comment by Ming
    err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_UUID_FILTER, &m_nus_uuid);
    APP_ERROR_CHECK(err_code);
    end by Ming */
    
    err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_NAME_FILTER, m_target_peripheral_name_1);              // set up peripheral name
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_NAME_FILTER, m_target_peripheral_name_2);              // set up peripheral name
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filters_enable(&m_scan, NRF_BLE_SCAN_NAME_FILTER, false);
    APP_ERROR_CHECK(err_code);
    

}

[Mttrinh]

Hi,

What SDK and softdevice are you using?

But the code doesn't work at all

Could you provide me with more information? What doesn't work? Are you not able to connect? Are you not able to send data?

What have you done so far? Have you made any modifications to the multilink example?

[laumung]

Hi Mttrinh, I modified the code based on nrf52-ble-app-uart-c-multilink-master from NordicPlayground on Github. I changed the scan_init() form SCAN_UUID_FILTER to SCAN_NAME_FILTER, which show below.

/**@brief Function for initializing the scanning and setting the filters.
 */
static void scan_init(void)
{
    ret_code_t          err_code;
    nrf_ble_scan_init_t init_scan;

    memset(&init_scan, 0, sizeof(init_scan));

    init_scan.connect_if_match = true;
    init_scan.conn_cfg_tag     = APP_BLE_CONN_CFG_TAG;
    
    /*
    err_code = nrf_ble_scan_init(&m_scan, &init_scan, scan_evt_handler);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_UUID_FILTER, &m_nus_uuid);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filters_enable(&m_scan, NRF_BLE_SCAN_UUID_FILTER, false);
    APP_ERROR_CHECK(err_code);
    */
    err_code = nrf_ble_scan_init(&m_scan, &init_scan, scan_evt_handler);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filter_set(&m_scan, SCAN_NAME_FILTER, m_target_peripheral_name_1);
    APP_ERROR_CHECK(err_code);

    err_code = nrf_ble_scan_filters_enable(&m_scan, NRF_BLE_SCAN_NAME_FILTER, false);
    APP_ERROR_CHECK(err_code);
    

}

After download the code, the debug information get from J-Linker RTT Viewer is shown below.

Actually what I want to do is to send and receive data to specific peripheral in the BLE network of multiple peripherals and centrals. The service of BLE is NUS (Nordic UART Service). What I planned is to name different peripherals different name and access them individually.

What's your suggestion? Thanks.

[Mttrinh]

Hi,

You need to increase the define NRF_BLE_SCAN_NAME_CNT to be able to add name filters.

[masterLee]

Hi,

I use the same multilink project for connecting 5 custom peripherals to one central (52840 DK). All peripheral devices are connected to the central . 

I want my custom peripherals to read simple commands and respond with an answer back to the central.

I have completed the first part where I send simple ble serial commands (a hex value) from a smartphone to one peripheral and the peripheral responds back to smartphone with a hex value. Now I want to do the same thing but from the nRF52840 DK when all peripherals are connected to it.

1. I don't know how to target a specific peripheral in order to send data to it. How can I do it?

2. I don't know hot to receive data from a specific peripheral. Do I need to do some kind of de-multiplexing in the code or something like that?

[Mttrinh]

Hi,

This thread might be helpful.

masterLee said:

2. I don't know hot to receive data from a specific peripheral. Do I need to do some kind of de-multiplexing in the code or something like that?

I'm not sure what you want to do here. You just have to send data from that specific peripheral.