BlueST SDK is a multi-platform library (Android, iOS, and Linux supported) that allows easy access to the data exported by a Bluetooth Low Energy (BLE) device that implements the BlueST Protocol.
Documentation can be found here.
This version of the SDK is compatible with Python 3.5 and runs on a Linux system.
The BlueST SDK makes use of the bluepy Python interface to Bluetooth Low Energy on Linux.
$ sudo pip3 install bluepyMoreover, it uses the concurrent.futures module to run pools of threads in background, that serve listeners' callbacks.
$ sudo pip3 install futuresThe BlueST SDK currently suffers from the following limitations, which are intrinsic to the bluepy library:
- When running a discovery process, the already connected devices get disconnected.
- There is no supervision timeout API within the SDK, hence it is not possible to detect immediately an unexpected disconnection; it is detected and notified via listeners as soon as a read/write/notify operation is executed on the device.
The BlueST SDK can be installed through the Python pip package manager.
$ sudo pip3 install blue-st-sdkBefore running the application examples, please prepare your devices as described here below. They need to be equipped with BLE connectivity and a FW compatible with the BlueST Protocol.
- The example_ble_1.py application example shows how to perform a BLE scan, connect to a device, retrieve its exported features, and get push notifications from it. You can use, for example, the SensorTile development kit and the FP-SNS-MOTENV1 function pack.
- The example_ble_2.py application example shows how to perform a BLE scan, connect to a number of devices handled though dedicated threads, and get push notifications from all their features.
- The example_ble_3.py application example shows how to connect to a BLE device exporting a "Stepper Motor" feature, to get its status, and to send commands to it. The application requires to set up a device equipped with BLE connectivity and a stepper motor control, e.g.:
- A NUCLEO-F401RE development board.
- An X-NUCLEO-IDB05A1 Bluetooth Low Energy expansion board.
- An X-NUCLEO-IHM01A1 Stepper Motor Driver expansion board, plus a proper stepper motor.
- Import the Node_BLE_StepperMotor_Device mbed OS application to your ARM mbed account, compile, and flash it onto the MCU board.
- Edit the application example and set the "MOTOR_DEVICE_MAC" global variable with the proper MAC address of your stepper motor enabled BLE device (which you can retrieve for example through a smartphone application).
- The example_ble_4.py application example shows how to handle two BLE devices exporting a "Switch" feature in such a way that pressing the user button on a device makes the LED of the other device toggle its state, through a logic defined within the application itself. The application requires to set up two devices equipped with BLE connectivity, e.g.:
- Two NUCLEO-F401RE development boards
- Two X-NUCLEO-IDB05A1 Bluetooth Low Energy expansion boards
- Import the Node_BLE_Switch_Device mbed OS application to your ARM mbed account, compile, and flash it onto the MCU board
- Edit the application example and set the "IOT_DEVICE_X_MAC" global variables properly (you can use a smartphone application to retrieve the MAC address)
- The example_ble_5.py application example shows how to connect to a microphone-enabled device exporting ADPCM or Opus audio features allowing to reproduce the recorded audio and eventually to dump it on a file. If your device exports "Beamforming" feature, you will be prompt to activate it.
- ADPCM Codec: You can use, for example, the BlueCoin development kit running FP-SNS-ALLMEMS1 function pack which expose "ADPCM Audio" and "ADPCM Sync" features.
- Opus Codec: You can use, for example, the SensorTile development kit running the FP-AUD-BVLINK2 function pack which expose "Opus Audio" and "Opus Conf" features. Please refer to the application example file for the software requirements.
- The example_ble_6.py application example shows how to connect to a device and perform a firmware upgrade. The application requires to set up a device equipped with a FW compatible with the BlueST Protocol that embeds a bootloader. Note that only when flashing manually the board the first time a firmware that embeds a bootloader is required, while the firmware that can be upgraded via BLE to the device does not have to embed any bootloader. Please use, for example, the firmware available within the FP-AI-SENSING1 function pack, which allows you to connect to IoT nodes and get Activity Recognition and Audio Scene Classification features. The function pack provides already binaries, both with and without the bootloader; just flash any of the firmware with the bootloader the first time, and try to upgrade it with another firmware without the bootloader previously stored on your gateway. Please refer to the application example file for the software requirements.
Other application examples can be found within the EdgeST SDK for Linux, an IoT edge computing abstraction library for Linux gateways.
By default, on Linux, the Bluetooth protocol stack needs special privileges to interact with. Hence, run the application examples as super-user by following the steps here below:
- Install the BlueST SDK as described by the Installation chapter.
- Clone the BlueST SDK git repository to download the application examples:
$ git clone https://github.com/STMicroelectronics/BlueSTSDK_Python.git
- Enter the "blue_st_examples" folder and run the desired script:
$ sudo python3 example_ble_x.py
The library shows only the devices that have a vendor-specific field formatted in the following way:
| Length | 1 | 1 | 1 | 1 | 4 | 6 |
|---|---|---|---|---|---|---|
| Name | Length | Field Type | Protocol Version | Device Id | Feature Mask | Device MAC (optional) |
| Value | 0x07/0x0D | 0xFF | 0x01 | 0xXX | 0xXXXXXXXX | 0xXXXXXXXXXXXX |
-
The Field Length must be 7 or 13 bytes long.
-
The Device Id is a number that identifies the type of device:
- 0x00 for a generic device.
- 0x01 is reserved for the STEVAL-WESU1 board.
- 0x02 is reserved for the STEVAL-STLKT01V1 (SensorTile) board.
- 0x03 is reserved for the STEVAL-BCNKT01V1 (BlueCoin) board.
- 0x04 is reserved for the STEVAL-IDB007VX (BlueNRG1) and STEVAL-IDB008VX (BlueNRG2) boards.
- 0x05 is reserved for the STEVAL-BCN002V1 (BlueTile) board.
- 0x06 is reserved for the STEVAL-MKSBOX1V1 (SensorTile.box) board.
- 0x07 is reserved for the B-L475E-IOT01A (STM32L4 Discovery kit IoT node) board.
- 0x80 for a generic Nucleo board.
In case you need to define your own custom boards, you should use Device Id values not yet assigned. Moreover, please note that values between 0x80 and 0xFF are reserved for ST Nucleo boards.
-
The feature mask is a bit field that provides information about the features exported by the board. Currently, bits are mapped in the following way:
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 Feature Analog ADPCM Sync Switch Direction of arrival ADPCM Audio Microphone Level Proximity Luxmeter Accelerometer Gyroscope Magnetometer Pressure Humidity Temperature Battery Second Temperature Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Feature CO Sensor DC Motor Stepper Motor SD Logging Beam forming Accelerometer Event Free Fall Sensor Fusion Compact Sensor Fusion Motion Intensity Compass Activity Recognition Carry Position Proximity Gesture MEMS Gesture Pedometer
To understand the way the data are exported by predefined features, please refer to the method Feature.extract_data(timestamp, data, offset) within the features class definition.
- The device MAC address is optional, and needed only on the iOS platform.
Currently only a subset of the features is implemented: Switch, Proximity, Accelerometer, Gyroscope, Magnetometer, Pressure, Humidity, Temperature, Second Temperature, Stepper Motor, Proximity Gesture, Activity Recognition, ADPCM Audio, and ADPCM Sync. Moreover, other features not listed among the default 32-bit feature mask, are provided, like for example the Audio Scene Classification. Future releases of the Python SDK will cover all the abovementioned features.
The characteristics managed by the SDK must have a UUID as follows: XXXXXXXX-0001-11e1-ac36-0002a5d5c51b.
The SDK scans all the services, searching for characteristics that match the pattern.
The first part of the UUID has bits set to "1" for each feature exported by the characteristics.
In case of multiple features mapped onto a single characteristic, the data must be in the same order as the bit mask.
A characteristic's data format must be the following:
| Length | 2 | >1 | >1 | |
|---|---|---|---|---|
| Name | Timestamp | First Feature Data | Second Feature Data | ..... |
The first 2 bytes are used to communicate a timestamp. This is especially useful to recognize any loss of data.
Since the BLE packet maximum length is 20 bytes, the maximum size of a feature's data field is 18 bytes.
The SDK is compatible with the following ST firmware:
- FP-SNS-MOTENV1: STM32 ODE function pack for IoT node with BLE connectivity plus environmental and motion sensors
- FP-SNS-ALLMEMS1: STM32 ODE function pack for IoT node with BLE connectivity, digital microphone, environmental and motion sensors
- FP-SNS-FLIGHT1: STM32 ODE function pack for IoT node with BLE connectivity, environmental and motion sensors, time-of-flight sensors (Please remove NFC when used with Python SDK)
This is a singleton class that starts/stops the discovery process and stores the retrieved nodes.
Before starting the scanning process, it is also possible to define a new Device Id and to register/add new features to already defined devices.
The Manager notifies a new discovered node through the ManagerListener class. Each callback is performed asynchronously by a thread running in background.
This class represents a remote device.
Through this class it is possible to recover the features exported by a node and read/write data from/to the device.
The node exports all the features whose corresponding bit is set to "1" within the advertising data message. Once the device is connected, scanning and enabling the available characteristics can be performed. Then, it is possible to request/send data related to the discovered features.
A node notifies its RSSI (signal strength) when created.
A node can be in one of following status:
- Init: dummy initial status.
- Idle: the node is waiting for a connection and sending an advertising data message (i.e. disconnected).
- Connecting: a connection with the node was triggered, the node is performing the discovery of device services/characteristics.
- Connected: connection with the node was successful.
- Disconnecting: ongoing disconnection; once disconnected the node goes back to the Idle status.
- Lost: the device has sent an advertising data, however it is not reachable anymore.
- Unreachable: the connection with the node was in place, however it is not reachable anymore.
- Dead: dummy final status.
Each callback is performed asynchronously by a thread running in background.
This class represents the data exported by a node.
Each feature has an array of Field objects that describes the data exported.
Data are received from a BLE characteristic and contained in a Sample class. The user is notified about new data through a listener.
Note that each callback is performed asynchronously by a thread running in background.
Available features can be retrieved from Features package.
-
Extend the Feature class:
- Create an array of
Fieldobjects that describe the data exported by the feature. - Create a constructor that accepts only the node as a parameter. From this constructor call the superclass constructor, passing the feature's name and the feature's fields.
- Implement the method
Feature.extract_data(timestamp, data, offset). - Implement a class method that allows to get data from a
Sampleobject.
- Create an array of
-
Register the new feature: If you want to use BlueST's bitmask for features within the advertising data, please register the new feature before performing the discovery process, e.g.:
# Adding a 'MyFeature' feature to a Nucleo device and mapping it to a custom # '0x10000000-0001-11e1-ac36-0002a5d5c51b' characteristic. mask_to_features_dic = {} mask_to_features_dic[0x10000000] = my_feature.MyFeature try: Manager.add_features_to_node(0x80, mask_to_features_dic) except BlueSTInvalidFeatureBitMaskException as e: print e # Synchronous discovery of Bluetooth devices. manager.discover(False, SCANNING_TIME_s)
Otherwise, you can register the feature after discovering a node and before connecting to it:
# Adding a 'FeatureHeartRate' feature to a Nucleo device and mapping it to # the standard '00002a37-0000-1000-8000-00805f9b34fb' Heart Rate Measurement # characteristic. map = UUIDToFeatureMap() map.put(uuid.UUID('00002a37-0000-1000-8000-00805f9b34fb'), feature_heart_rate.FeatureHeartRate) node.add_external_features(map) # Connecting to the node. node.connect()
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