BLEUart

The Bluefruit nRF52 BSP codebase is undergoing active development based on customer feedback and testing. As such, the class documentation here is incomplete, and you should consult the Github repo for the latest code and API developments: https://goo.gl/LdEx62

BLEUart is a wrapper class for NUS (Nordic UART Service), which is a proprietary service defined by Nordic Semiconductors that we use as a baseline transport mechanism between Bluefruit modules and our mobile and desktop Bluefruit LE Connect applications. You can use it to easily send ASCII or binary data in both directions, between the peripheral and the central device.

API

BLEUart has the following public API:

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// RX Callback signature (fires when data was written by the central)
typedef void (*rx_callback_t) (void);

// Constructor
BLEUart(uint16_t fifo_depth = BLE_UART_DEFAULT_FIFO_DEPTH);

virtual err_t begin(void);

bool notifyEnabled(void);

void setRxCallback( rx_callback_t fp);

// Stream API
virtual int       read       ( void );
virtual int       read       ( uint8_t * buf, size_t size );
virtual size_t    write      ( uint8_t b );
virtual size_t    write      ( const uint8_t *content, size_t len );
virtual int       available  ( void );
virtual int       peek       ( void );
virtual void      flush      ( void );

// Pull in write(str) and write(buf, size) from Print
using Print::write;

Example

The following example shows how to use the BLEUart helper class.

This example may be out of date, and you should always consult the latest example code in the nRF52 BSP!

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#include <bluefruit.h>

BLEDis  bledis;
BLEUart bleuart;
BLEBas  blebas;

#define STATUS_LED  (17)
#define BLINKY_MS   (2000)

uint32_t blinkyms;

void setup()
{
  Serial.begin(115200);

  Serial.println("Bluefruit52 BLEUART Example");

  // Setup LED pins and reset blinky counter
  pinMode(STATUS_LED, OUTPUT);
  blinkyms = millis();

  // Setup the BLE LED to be enabled on CONNECT
  // Note: This is actually the default behaviour, but provided
  // here in case you want to control this manually via PIN 19
  Bluefruit.autoConnLed(true);

  Bluefruit.begin();
  Bluefruit.setName("Bluefruit52");
  Bluefruit.setConnectCallback(connect_callback);
  Bluefruit.setDisconnectCallback(disconnect_callback);

  // Configure and Start Device Information Service
  bledis.setManufacturer("Adafruit Industries");
  bledis.setModel("Bluefruit Feather52");
  bledis.begin();

  // Configure and Start BLE Uart Service
  bleuart.begin();

  // Start BLE Battery Service
  blebas.begin();
  blebas.update(100);

  // Set up Advertising Packet
  setupAdv();

  // Start Advertising
  Bluefruit.Advertising.start();
}

void setupAdv(void)
{
  Bluefruit.Advertising.addFlags(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE);
  Bluefruit.Advertising.addTxPower();

  // Include bleuart 128-bit uuid
  Bluefruit.Advertising.addService(bleuart);

  // There is no room for Name in Advertising packet
  // Use Scan response for Name
  Bluefruit.ScanResponse.addName();
}

void loop()
{
  // Blinky!
  if (blinkyms+BLINKY_MS < millis()) {
    blinkyms = millis();
    digitalToggle(STATUS_LED);
  }

  // Forward from Serial to BLEUART
  if (Serial.available())
  {
    // Delay to get enough input data since we have a
    // limited amount of space in the transmit buffer
    delay(2);

    uint8_t buf[64];
    int count = Serial.readBytes(buf, sizeof(buf));
    bleuart.write( buf, count );
  }

  // Forward from BLEUART to Serial
  if ( bleuart.available() )
  {
    uint8_t ch;
    ch = (uint8_t) bleuart.read();
    Serial.write(ch);
  }
}

void connect_callback(void)
{
  Serial.println("Connected");
}

void disconnect_callback(uint8_t reason)
{
  (void) reason;

  Serial.println();
  Serial.println("Disconnected");
  Serial.println("Bluefruit will start advertising again");
}
This guide was first published on Mar 22, 2017. It was last updated on Mar 22, 2017. This page (BLEUart) was last updated on May 19, 2019.