Android and TI-RTOS applications that communicate over BLE. Android app reads the rotation vector from the phone (only the pitch and roll), and sends it to the TI-RTOS BLE application (firmware is installed on the CC-1350 launchpad).
Motivation
Our initial goal was to make the Metal Marble Labyrinth Puzzle accesible, the game:
As one can see in the image, the game requires using both hands (one for axis controller). With our implementation, one can play this game with one (or none) hand. Besides the mentioned game, the software can be used for several application such as: model airplanes or ships, etc.
Equipment
TI CC1350 Launchpad:
2 * SG-90 servo engines:
Samsung Galaxy S3:
Bread Board:
Implementation
Android application
Used Android Studio 3.0.1 for the development process.
Development process:
Using Android Sensor API to read the Rotation Vector (Pitch and Roll only), Used this example for the implementation. The pitch and roll orientation:
For the BLE connection establishment with the micro-controller we used this example, from Google's Android examples Github.
We changed the UI of the above example, and added the BLE writing data functionality.
Finally, we combined both applications, so it will the read the rotation vector of the phone, and send it immediately to the micro-controller.
Application flow:
Android application looks for the exact TI-RTOS application name in all optional BLE devices. If not found - raises an appropriate "Toast" message.
If found, by the end of the scan, a "start" button will appear. Upon user's click on the "start" button the application will try to connect to the micro-controller.
After connection is established, a listener for the rotation vector will be automatically registered, and in each vector read - the app will send the degree to the micro-controller.
To end the connection - the user can click the "pause" button.
Technical details:
Rotation vector sample rate is 120ms.
Each time only one of {pitch, roll} is sent. The synchronization between the orientation (pitch/roll) and the corresponding servo engine is done by the MSB of the written data.
Data is written on the 0xfff3 write characteristic of the TI-RTOS app.
Limited the degrees to [-60, 60].
TI-RTOS application (servo engines control)
Used Code Composer Studio 7.3.0 for the development process.
Development process:
Using Simple BLE Peripheral example from the TI-RTOS examples library to establish the BLE connection to the Galaxy S3 device.
Used the TI-RTOS PWM API to generate output pulses, which will determine the engines position.
Used the SG90 datasheet to create a linear mapping from the required degree to the appropriate pulse width (measured in ms).
Application flow:
Upon established connection, start reading the data from the 0xfff3 write characteristic.
The read data will then be mapped to respective pulse width to the PIN output.
Servo engines will be positioned accordingly.
Technical details:
The linear mapping between the degree (deg) and pulse width (pw): pw = (deg/90 + 1.75) * 1000
Upon reading the data, it is masked to get the MSB and to output to the corresponding engine.
Limited the degrees to [-60, 60].
Demonstration:
Our learning process
Android
First, we started by learning how write a simple "Hello, world" Android application, using Android Studio.
After getting the hang of it, we wrote a slightly more complex application, which reads the rotation vector of the mobile device and displaying it on screen.
Finally, after we have "mastering" the app writing skills, we wrote the main application mentioned above.
TI-RTOS
First, we needed to remember on how to read data using BLE protocol (as we did on HW5).
Controlling servo engines:
First, we read the SG90 datasheet, and studied which pulse the engine needs to be in which degree.
To output the appropriate pulse width we used the PWM API, that we have used in the PWMLed exercise.
