how to send uart data over ble with nrf52840 dongle

Question

I'm working on pca10059(nRF52840 dongle) to send UART data over bluetooth to another device. 
 My test environment is, 
 Arduino Uno to send uart signal using "mySerial.write("Hello World
");", 
 pca10059 device that I'm trying to develop to send uart data above to another device over bluetooth, 
 another pca10059 device to receive the data over bluetooth and send Serial signal to see the data on PC to make sure the "Hello World" travels fine. 
 
 (1) I've modified the project in example/ble_peripheral/ble_app_uart to send arbitrary data(series of uint8_t signal) to another dongle and I could see the data in Python IDLE. 
 (2) I've checked the arduino wiring is correct by testing a project below link. 
 https://devzone.nordicsemi.com/f/nordic-q-a/56406/how-to-set-up-a-simple-uart-connection-between-nrf-52840-dongle-and-a-microcontroller-e-g-arduino 
 I've changed the code (1) a little bit to see if I could send uart to the other dongle. It didn't work. 
 Most of what I've done is changing the TX RX pin number to suit wiring setup. 
 What's hard to understand is the project already has uart_event_handle function in the main.c and it uses ble_nus_data_send function just like (1) but it seems it's not responding to uart signal sent from arduino or it's not sending the received uart signal. 
 uart_init() was also called to activate uart. 
 Although I couldn't check arduino's uart signal, I'm quite sure (2) project's success in test indicates it's not a problem of connection or arduino code. Correct me if I'm wrong.

Senchoi · Accepted Answer

Although I felt very lucky to get these replies. 
 I think I've found out why uart_event_handle didn't send the data. 
 void uart_event_handle(app_uart_evt_t * p_event)
{
 static uint8_t data_array[BLE_NUS_MAX_DATA_LEN];
 static uint8_t index = 0;
 uint32_t err_code;

 switch (p_event->evt_type)
 {
 case APP_UART_DATA_READY:
 UNUSED_VARIABLE(app_uart_get(&data_array[index]));
 index++;

 if ((data_array[index - 1] == '
') ||
 (data_array[index - 1] == '') ||
 (index >= m_ble_nus_max_data_len))
 {
 if (index > 1)
 {
 NRF_LOG_DEBUG("Ready to send data over BLE NUS");
 NRF_LOG_HEXDUMP_DEBUG(data_array, index);

 do
 {
 uint16_t length = (uint16_t)index;
 err_code = ble_nus_data_send(&m_nus, data_array, &length, m_conn_handle);
 printf("%s
", data_array);
 if ((err_code != NRF_ERROR_INVALID_STATE) &&
 (err_code != NRF_ERROR_RESOURCES) &&
 (err_code != NRF_ERROR_NOT_FOUND))
 {
 APP_ERROR_CHECK(err_code);
 }
 } while (err_code == NRF_ERROR_RESOURCES);
 }

 index = 0;
 }
 break;

 case APP_UART_COMMUNICATION_ERROR:
 APP_ERROR_HANDLER(p_event->data.error_communication);
 break;

 case APP_UART_FIFO_ERROR:
 APP_ERROR_HANDLER(p_event->data.error_code);
 break;

 default:
 break;
 }
} 
 The function above has certain condition for sending data over ble. 
 if ((data_array[index - 1] == '
') || (data_array[index - 1] == '') || (index >= m_ble_nus_max_data_len)) 
 this seems the part that I should've understood. When sending the data from Arduino I had to send '
' at the end. 
 It seems above handler waits for the condition above. 
 This is the Arduino code that works now. 
 #include <SoftwareSerial.h>

SoftwareSerial mySerial(2, 3); // RX, TX

void setup()
{
 // Open serial communications and wait for port to open:
 Serial.begin(115200);
 while (!Serial) {
 ; // wait for serial port to connect. Needed for Native USB only
 }


 Serial.println("Goodnight moon!");

 // set the data rate for the SoftwareSerial port
 mySerial.begin(115200);
 mySerial.println("Hello, world?");
}
char c = 'a';
void loop() // run over and over
{
 
 if (mySerial.available()){
 Serial.write(mySerial.read());
 if (c == 'z' + 1)
 c = 'a';
 mySerial.write(c++);mySerial.write('
');
 }
 delay(500);
} 
 I can see the sent data from python shell with the setup I had. 
 I have tones of other questions but I guess I can wrap it up for now.

how to send uart data over ble with nrf52840 dongle

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