ANT is an ultra low power wireless protocol that can communicate for years using a single coin cell battery. It allows hundreds of transmitters to coexist on the same RF channel without collision. ANT networks can be built in various topologies including point-to-point, broadcast, star, shared, and asynchronous configurations. ANT+ defines common data formats for what information is sent over ANT networks. The Android ANT API and ANT+ profile plugins make implementing ANT+ applications simpler through a common interface and by handling device discovery and data interpretation.

1. Harrison Chin
Applications Engineer
harrison.chin@thisisant.com

2. Thank You!

3. What is ANT or ANT+?
• ANT is an ultra low power 2.4GHz wireless protocol
– Shipped over 60+ Million devices so far
– Can communicate for years using a single coin cell battery
– Hundreds of transmitters can co-exist on the same RF
channel without collision
– Simple logical channels can be used separately or
combined into complex topologies
– Highly compact stack and common API across vendors
– 8 byte Payload Broadcast and Acknowledged packets
• Up to 24 byte Burst message packets
• ANT+ is a set of mutually agreed upon definitions for
what the information sent over ANT represents

5. Building ANT Networks…Simply
• Point-to-point M S

6. Building ANT Networks…Simply
• Point-to-point
• Broadcast one-to-many
M
S S
S

7. Building ANT Networks…Simply
• Point-to-point
• Broadcast one-to-many

8. Building ANT Networks…Simply
• Point-to-point
• Broadcast one-to-many
S
• Star
M
S S
M M

9. Building ANT Networks…Simply
• Point-to-point
• Broadcast one-to-many
• Star

10. Building ANT Networks…Simply
• Point-to-point
• Broadcast one-to-many
• Star
• Shared S S S
M
S S S

11. Building ANT Networks…Simply
• Point-to-point
• Broadcast one-to-many
• Star …
• Shared M M M
…
M
• Asynchronous Over the Air
Scan Scan
M M

12. Building ANT Networks…Simply
• Point-to-point
• Broadcast one-to-many
• Star
• Shared
• Asynchronous
1: Is 1: Is
that that
fun? fun?
2:No 2:No
idea… idea…

13. ANT Networks…
Simple to Sophisticated
• Point-to-point
• Broadcast one-to-many
• Star
• Shared
• Asynchronous
• Beyond the star…

14. Co-existence Management –
Time Domain

15. Background Scanning Channel
• Background scanning channel is receive only
• Allows independent channels to stay open on the same physical
radio
• Useful to create asynchronous topologies, monitor messages, RSSI
pairing schemes, etc
MASTER_1
MASTER_2
Background
Scanning

16. Continuous Scanning Mode
• ‘Always on’ receiver: high power M
M
• Fully Bi-directional Communication Scan
M
– Channels can be responded to on-demand M
M
• Masters can transmit intermittently
• Potentially hundreds of transmitters to one center node
MASTER_1
MASTER_2
Scanning
Mode

17. ANT+ Device Profiles
• Open definitions for device-level
interoperability
– Channel configuration
– Data format
– Data exchange mechanisms

18. ANT+ Device Profiles

19. Control
Bidirectional communication
Sensor: status
Display: control

20. Geocache
Hint
Next location
Visitor count

21. Bicycle Speed & Cadence
Bicycle Power
Cadence
Speed
Power

22. Activity Monitor
Access Searching…
Point

23. Continuous Glucose Monitor
Authenticated sessions
Intermittent transmission scheme
Live and stored data

24. ANT+ Interoperability

25. Android ANT Layers
App App App App App App
Created by: Profiles
ANT Radio Service
For Connectivity Chip For ANT USB sticks
ANT HAL Service ANT USB Service
Applications
ANT HAL
Created by:
ANT Transport Driver
& Chip Physical Transport Driver Android USB Host Feature
Vendor Vendor Specific Library Android System Android
Android System
ANT Firmware ANT Firmware
Combo Connectivity Device ANT USB Stick

26. Android Components
App App App
Profiles
ANT+ Profile ANT+ Profile
Plug-in Plug-in
ANT Radio Service
Applications
ANT HAL Service
ANT HAL
Android System
ANT Firmware
Combo Connectivity Device

27. ANT+ Profile Plug-ins
Make Implementing ANT+ Applications Easier
App App
Heart Rate PCC Remote Control PCC
ANT+ API
Heart Rate Plug-in Control Plug-in
Plug-ins
ANT Channel Provider ANT Channel
Channel API/ANT Radio Service

28. Plug-in Communicator Class
• A simple class which provides access to the
ANT+ Plug-in
• Methods include…
public static void requestAccess(…)
public String getDeviceName()
public int getAntDeviceID()
public int getCurrentDeviceState()
public void subscribeTo<EventName>(...)
public void releaseAccess()

29. Request Access
public static void requestAccess(
Activity userActivity,
Context bindToContext,
boolean skipPreferredSearch,
IPluginAccessResultReceiver<AntPlusHeartRatePcc> resultReceiver,
IDeviceStateChangeReceiver stateReceiver)

30. Device Discovery UI

31. Result Receiver
public void onResultReceived(AntPlusHeartRatePcc result,
int resultCode,
int initialDeviceStateCode,
Object asyncState)
{
switch(resultCode)
{
case AntPluginMsgDefines.MSG_REQACC_RESULT_whatSUCCESS:
hrPcc = result;
subscribeToEvents();
break;

32. Result Receiver
case AntPluginMsgDefines.MSG_REQACC_RESULT_whatDEPENDENCYNOTINSTALLED:
AlertDialog.Builder adlgBldr;
adlgBldr = new AlertDialog.Builder(Activity_HeartRateSampler.this);
adlgBldr.setTitle("Missing Dependency");
adlgBldr.setMessage("The required applicationn"" +
AntPlusHeartRatePcc.getMissingDependencyName() +
“"n is not installed. Do you want to launch the Play Store to search for it?");
...
break;

33. Subscribing to Events
hrPcc.subscribeHeartRateDataEvent(
new IHeartRateDataReceiver()
{
public void onNewHeartRateData(
final int currentMessageCount,
final int computedHeartRate,
final int heartBeatCounter,
final int timestampOfLastBeat_1024s)
{
//Use data...
}
} );

34. State Change Receiver
public void onDeviceStateChange(int newDeviceState)
{
//Handle state change:
//(TRACKING, SEARCHING, CLOSED, DEAD)
}

35. Release Access
public static void releaseAccess()
• Releases the connection to the device (the plugin
service will automatically shutdown when all apps
have released access)

36. Channel Interface
• Used for non-ANT+ applications
• Development of Beta ANT+ profiles
• Provides channels from all connected chips
• Gives full access to individual ANT channel
capabilities
– Background scanning
– Shared channels
– Decimated receive rates

37. General Channel Flow
1. Bind to the ANT Radio Service
2. Get the ANT Channel Provider
3. Acquire Channel(s)
4. Configure Channel(s)
5. Use Channel(s)
6. Release the Channel(s) and Unbind

38. Bind to the ANT Radio Service
private AntService mAntRadioService = null;
private AntChannelProvider mAntChannelProvider = null;
private ServiceConnection mAntRadioServiceConnection =new ServiceConnection()
{
@Override
public void onServiceConnected(ComponentName name, IBinder service)
{
mAntRadioService = new AntService(service);
mAntChannelProvider = mAntRadioService.getChannelProvider();
}
…
}

39. Acquire a Channel
AntChannel acquireChannel() throws ChannelNotAvailableException
{
AntChannel antChannel = null;
if(null != mAntChannelProvider)
{
antChannel = AntChannelProvider.acquireChannel(this, PredefinedNetwork.PUBLIC);
}
return antChannel;
}

40. Configuring an ANT Channel…
• setAdapterWideLibConfig(LibConfig libConfig)
• setChannelId(ChannelId channelId)
• setPeriod(int period_32768unitsPerSecond)
• setTransmitPower(int outputPowerLevelSetting)
• setProximityThreshold(int searchThreshold)
• setRfFreqency(int radioFrequencyOffset)
• setSearchTimeout (LowPrioritySearchTimeout lowPrioritySearchTimeout)
• …and more representing standard ANT Message Commands

41. Handling the Channel
public class ChannelCallback implements AntChannelMessageHandler
{
@Override
public void handleMessage(AntMessageFromAnt antMessage)
{
switch(antMessage.getMessageType())
{
case BROADCAST_DATA:
case ACKNOWLEDGED_DATA:
// Rx Data
DataMessage rxMessage = (DataMessage)antMessage;
processData(rxMessage.getPayload());
break;
case CHANNEL_EVENT:
…
}
}
}

42. Releasing the Channel
public void close()
{
if (null != mAntChannel)
{
mAntChannel.release();
mAntChannel = null;
}
}

43. What could you do with…
• Simplicity
– ANT+ Android Plug-ins
handle discovery and
profile interpretation for
the developer
– Unified ANT API across
multiple vendors minimizes
support costs
– Small stack size and TDMA
style coexistence reduces
memory and
computational costs
– Individual logical channels
are easy to work with

44. What could you do with…
• Extreme network
flexibility
– Enables large scale
networks for small, coin
cell operated devices
Over the
running for years
Air
– Hubs, phones, access
points, etc can gather data
and communicate
concurrently
– Scatternets, meshes, trees,
etc, can be dynamically
created and closed
– Simple channels are the
building blocks

45. Thank You!
Have a Great Droidcon!