Ble central- BLE app multilink using UART for other MCU connections

[PeteKcSum]

Hi NordicS,

We have a project that uses multiple BT peripheral devices connected to various sensors, and 3 BT centrals that are connected to a MCU that acts as the "mainframe" for collecting the data that is retrieved from the peripherals via the BT centrals. As such, we need to modify the BT centrals to be able to use UART for communicating with the external mainframe MCU. The reason for using UART is so that we could use terminals and send AT like commands to control the BT centrals.

I have tested the BLE app multilink example and made sure it is able to connect to peripheral device. works fine. Specified the slave device name and upon reboot it searches for the slave and conects automatically.

After that I tried to integrate the "peripheral\UART -  example" to the central app, which failed. Next i disabled the nRF log feature, which also does not help. The BT central cannot automatically connect to the slave device anymore. Any clue would be appreciated. thx

[Simon]

Could you try to debug your program, and figure out exactly where it's failing? Also, could you provide some logs as well? Either through printf() or NRF_LOG with RTT as backend, I think NRF_LOG with UART as a backend interferes with the peripheral/uart example.

Best regards,

Simon

[PeteKcSum]

thx Simon. did as suggested, and unsurprisingly the program halts right  where the UART needs to be initialized  ( const app_uart_comm_params_t comm_params ). Below is the modified code.

int main(void)
{
    // Initialize.
    //log_init();
    timer_init();
    leds_init();
    buttons_init();
    power_management_init();
    ble_stack_init();
    gatt_init();
    db_discovery_init();
    lbs_c_init();
    ble_conn_state_init();
    scan_init();
    scan_start();
//////////////////////////
    bsp_board_init(BSP_INIT_LEDS);
    uint32_t err_code;

    const app_uart_comm_params_t comm_params =
      {
          ARDUINO_SDA_PIN, //RX_PIN_NUMBER,
          ARDUINO_SCL_PIN, //TX_PIN_NUMBER,
          RTS_PIN_NUMBER,
          CTS_PIN_NUMBER,
          UART_HWFC,
          false,
#if defined (UART_PRESENT)
          NRF_UART_BAUDRATE_115200
#else
          NRF_UARTE_BAUDRATE_115200
#endif
      };
               
    APP_UART_FIFO_INIT(&comm_params,
                         UART_RX_BUF_SIZE,
                         UART_TX_BUF_SIZE,
                         uart_error_handle,
                         APP_IRQ_PRIORITY_LOWEST,
                         err_code);

    APP_ERROR_CHECK(err_code);


    
    /*// Start execution.
    //NRF_LOG_INFO("Multilink example started.");
    for (;;)
    {
        idle_state_handle();
    }*/
        
    printf("\r\nUART example started.\r\n");

    while (true)
    {
        uint8_t cr,hr,lr, total_cmd_length = 0;
        uint8_t received_cmd[BUF_LENGTH] ;
      
            while (true)
            {
                while (app_uart_get(&cr) != NRF_SUCCESS );
               ................

                  //do sth
                    printf(" received %x !",cr);
                                    
                }
            };
                
                for (int i=0; i < total_cmd_length; i++ ){
                    printf(" \r\n received %0.2x,total length of cmd %0.2x !\r\n",received_cmd[i],total_cmd_length);
                }
                    printf(" \r\n received %0.2x!\r\n",received_cmd[0]+received_cmd[1]+received_cmd[2]);
                
        if (cr == 'q' || cr == 'Q')
        {
            printf(" \r\nExit!\r\n");

            while (true)
            {
                // Do nothing.
            }
        }
    }    
        
}

As seen above, the code has been changed so that log is not inited, the sdk_config has been updated accordingly and disabled the nRF log. Then right where the idle_state_handle is to be called has been replaced by the UART app_uart_get loop. The code compiles , but halts right where UART is to be initialized. Any ideas would be appreciated, thx.

[PeteKcSum]

thx for your effort Simon. unfortunately I wasn't able to make it work here. The compilation was not successful right after downloading ; app_uart.c and nrf_queue.c and some other files were required to be added to the working folders, and the paths were added accordingly for those files. The sdk_config.h also needed definitions to be added for those functions related to work and compile correctly.

However after compiling, the application still crashed with fatal error and reset. The culprit was the fifo_init function, once this was commented , the application no longer crashed.

May i ask the software environment ? On the side note, the hardware i am using is not the Nordic dongle, but a 3rd party nRF52840 eval kit, but it shouldn't be  causing the software issue, right ? thx.

[bbslhb]

Hi, Simon, can you tell which version of SDK are you  using?

I am using "nRF5_SDK_15.2.0_9412b96" and failed to build your project in the zip file.

[Simon]

I used nRF5_SDK_15.3.0_59ac345 and the nRF52832 DK (I didn't have the nRF52840 at hand when creating the example).

I will test it tomorrow with the nRF52840 DK and SDK 15.2, and see if I am able to make it work.

Best regards,

Simon

[bbslhb]

Hi, Simon.Thanks for your reply.

I can build it on SDK_15.3.0 now.

But I still can't use printf.

I think the purpose for this question is to use UART of the BLE central to communicate with PC.

For example: I flash your sample code into nRF52xxx and nRF52xxx became a BLE central.

After power on, it begin to scan all BLE peripherals and printf all the BLE names through the uart.

[Simon]

Test out this example:

 ble_app_multilink_central_uart.zip

Best regards,

Simon