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  • Case ID: 312529
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When using NUS, configure communication protocol

David_Kim

hello!

I am developing communication using Nordic UART Service.

 

It defines the protocol of data sent by the ble_nus_data_send() function.

( err_code = ble_nus_data_send(&m_nus, data_array, &length, m_conn_handle); )

When composing a communication protocol, for reliability, it usually starts with STX (0x02) and ends with ETX (0x03) and uses length and checksum.

|STX | Length | data~~~~~~ | checksum | ETX |

By the way, if Nordic UART Service is used this time, I think there will be a data structure for reliability as above in the payload of Nordic UART Service. Is it okay to omit it and transmit only data?

|STX | Length | data~~~~~~ | checksum | ETX |    =====>   only data~~~~~~ 

Additionally, I want to see the data packets from NUS, but I can't find them. If it is public, please link.

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    I think using NUS gives you flexibility regarding data structure. It's doable for you to send your data structure with NUS. You can check example from nRF52-ADC to see how they use NUS to send ADC values from multiple channels.

     // Send data over BLE via NUS service. Create string from samples and send string with correct length.
        uint8_t nus_string[50];
        bytes_to_send = sprintf(nus_string, 
                                "CH0: %d\r\nCH1: %d\r\nCH2: %d\r\nCH3: %d",
                                p_event->data.done.p_buffer[0],
                                p_event->data.done.p_buffer[1],
                                p_event->data.done.p_buffer[2],
                                p_event->data.done.p_buffer[3]);

        err_code = ble_nus_data_send(&m_nus, nus_string, &bytes_to_send, m_conn_handle);
        if ((err_code != NRF_ERROR_INVALID_STATE) && (err_code != NRF_ERROR_NOT_FOUND))
        {
            APP_ERROR_CHECK(err_code);
        }

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  • 0

    I think using NUS gives you flexibility regarding data structure. It's doable for you to send your data structure with NUS. You can check example from nRF52-ADC to see how they use NUS to send ADC values from multiple channels.

     // Send data over BLE via NUS service. Create string from samples and send string with correct length.
        uint8_t nus_string[50];
        bytes_to_send = sprintf(nus_string, 
                                "CH0: %d\r\nCH1: %d\r\nCH2: %d\r\nCH3: %d",
                                p_event->data.done.p_buffer[0],
                                p_event->data.done.p_buffer[1],
                                p_event->data.done.p_buffer[2],
                                p_event->data.done.p_buffer[3]);

        err_code = ble_nus_data_send(&m_nus, nus_string, &bytes_to_send, m_conn_handle);
        if ((err_code != NRF_ERROR_INVALID_STATE) && (err_code != NRF_ERROR_NOT_FOUND))
        {
            APP_ERROR_CHECK(err_code);
        }

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