Bluetooth LE

ITP | Week 1 | February 5, 2016

Don Coleman

Lightbulb Service

  • Light Switch
  • Dimmer Setting

Lightbulb Service - FF10

16 bit UUIDs

0000FF10-0000-1000-8000-00805F9B34FB

0000FF11-0000-1000-8000-00805F9B34FB

0000FF12-0000-1000-8000-00805F9B34FB

Lightbulb Service - FF10

Advertising

Advertising

  • 5425B44A-024A-4D39-88D2-D9F016199B29
  • Services: [ 0x180A, 0xFF10, 0XFF20, …]
  • Manufacturer Data: <00007465 6d70>
  • Connectable: True
  • TX Power Level: 4
  • RSSI: -80
  • Name: LED

Connect

Read Value

Write Value

Write Command

Heart Rate Service - 180d

org.bluetooth.service.heart_rate.xml
org.bluetooth.characteristic.heart_rate_measurement.xml

Notification

Indication

Peripheral

Provides services

Central

  • Discover advertising peripherals
  • Connect using MAC Address or UUID
  • Explore the services and characteristics
  • Read and write characteristics
  • Subscribe to be notified of changes

Today we'll build peripherals that

  • Control a LED
  • Send button state
  • Send temperature data

Arduino BLE Peripheral


https://github.com/sandeepmistry/arduino-BLEPeripheral

RedBear Blend
RFduino

Adafruit Bluefruit LE nRF8001 Breakout

RedBear BLE Shield 2.1

Other RedBear boards

Exercise 1

Blink

Blink.ino

#define LED_PIN 6

void setup() {
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  digitalWrite(LED_PIN, HIGH);   // turn the LED on
  delay(1000);                   // wait one second
  digitalWrite(LED_PIN, LOW);    // turn the LED off
  delay(1000);                   // wait one second
}
                

Exercise 2

Bluetooth LED

Lightbulb Service - FF10

LED.ino


  #include <SPI.h>
  #include <BLEPeripheral.h>

  #define LED_PIN  6
	

Create BLE Peripheral


#define BLE_REQ  9
#define BLE_RDY  8
#define BLE_RST  5

BLEPeripheral blePeripheral =
   BLEPeripheral(BLE_REQ, BLE_RDY, BLE_RST);
	

Create Service


BLEService ledService = BLEService("FF10");
	

Characteristic & Descriptor


BLECharCharacteristic switchCharacteristic
  = BLECharCharacteristic("FF11", BLERead | BLEWrite);
BLEDescriptor switchDescriptor
  = BLEDescriptor("2901", "Switch");
	

Setup

void setup() {
  Serial.begin(9600);
  pinMode(LED_PIN, OUTPUT);

  blePeripheral.addAttribute(ledService);
  blePeripheral.addAttribute(switchCharacteristic);
  blePeripheral.addAttribute(switchDescriptor);
  // ...
}
	

Setup

void setup() {
  // ...
  switchCharacteristic.setEventHandler(
              BLEWritten, switchCharacteristicWritten);

  blePeripheral.setAdvertisedServiceUuid(
                                    ledService.uuid());
  blePeripheral.setLocalName("LED");
  blePeripheral.begin();
}
	

Loop


  void loop() {
    blePeripheral.poll();
  }
	

Switch Characteristic Written

void switchCharacteristicWritten(
	  BLECentral& central,
	  BLECharacteristic& characteristic) {

  if (switchCharacteristic.value()) {
    Serial.println(F("LED on"));
    digitalWrite(LED_PIN, HIGH);
  } else {
    Serial.println(F("LED off"));
    digitalWrite(LED_PIN, LOW);
  }
}
	

Exercise 3

Dimmable LED

Lightbulb Service - FF10

Characteristic & Descriptor


BLEUnsignedCharCharacteristic dimmerCharacteristic
 = BLEUnsignedCharCharacteristic("FF12",
                                 BLERead | BLEWrite);
BLEDescriptor dimmerDescriptor
 = BLEDescriptor("2901", "Dimmer");
	

Setup

void setup() {
  // ...
  blePeripheral.addAttribute(dimmerCharacteristic);
  blePeripheral.addAttribute(dimmerDescriptor);
  // ...
  dimmerCharacteristic.setEventHandler(
              BLEWritten, dimmerCharacteristicWritten);
  // ...
}

Dimmer Characteristic Written

void dimmerCharacteristicWritten(
	  BLECentral& central,
	  BLECharacteristic& characteristic) {
  Serial.print(F("Dimmer set to: "));
  Serial.println(dimmerCharacteristic.value());

  analogWrite(LED_PIN, dimmerCharacteristic.value());
}
	

Exercise 4

Button

Button Service - FFE0

Service, Characteristic, & Descriptor


BLEService buttonService = BLEService("FFE0");

BLECharCharacteristic buttonCharacteristic =
        BLECharCharacteristic("FFE1", BLENotify);

BLEDescriptor buttonDescriptor =
        BLEDescriptor("2901", "Button State");
                

Loop


void loop() {
  blePeripheral.poll();
  char buttonValue = digitalRead(BUTTON_PIN);

  if (buttonCharacteristic.value() != buttonValue) {
    Serial.print("Button ");
    Serial.println(buttonValue, HEX);
    buttonCharacteristic.setValue(buttonValue);
  }
}
                

Button v2

Limit Button Read


void loop() {
  blePeripheral.poll();

  // limit how often we read the button
  if (millis() - lastReadTime > readInterval) {
    readButton();
    lastReadTime = millis();
  }
}
                

Read Button


void readButton() {
  char buttonValue = digitalRead(BUTTON_PIN);

  // has the value changed since the last read?
  if (buttonCharacteristic.value() != buttonValue) {
    Serial.print("Button ");
    Serial.println(buttonValue, HEX);
    buttonCharacteristic.setValue(buttonValue);
  }
}
                

Exercise 5

Thermometer

Thermometer Service - 0xBBB0


Analog Temperature Sensor TMP36

Service, Characteristic, & Descriptor


  BLEService thermometerService = BLEService("BBB0");
  BLEFloatCharacteristic temperatureCharacteristic
      = BLEFloatCharacteristic("BBB1",
                               BLERead | BLENotify);
  BLEDescriptor temperatureDescriptor
      = BLEDescriptor("2901", "degrees C");
            	

Loop

void loop()
{
  blePeripheral.poll();

  if(millis() - previousMillis > interval) {
    pollTemperatureSensor();
    previousMillis = millis();
  }
}

Poll Temperature Sensor

void pollTemperatureSensor()
{
  float temp = calculateTemperature();

  if (tempCharac.value() != temp) {
    tempCharac.setValue(temp);
    Serial.println(temp);
  }
}

Calculate Temperature

float calculateTemperature()
{
  // read the sensor value
  int sensorValue = analogRead(TEMPERATURE_PIN);

  float voltage = sensorValue * 5.0;
  voltage /= 1024.0;
  // 100 degrees per volt with 0.5 volt offset
  float temperature = (voltage - 0.5) * 100;

  return temperature;
}

http://bit.ly/bluetooth-book

Don Coleman

dc159@nyu.edu

http://don.github.io/slides/2016-02-05-itp-bluetoothle

 

 

Creative Commons License
Bluetooth LE ITP Week 1 by Don Coleman
is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
Based on a work at https://github.com/don/.../2016-02-05-itp-bluetoothle.