CapBot-BLE-Control
Description: In this example the robot behaves as a Bluetooth Low Energy peripheral hosting a GATT server with a custom "Robot Control Service".
- Primary Functionality: Provide CapBot BLE control.
- Target: Custom hardware
- Task: T4.1
- Responsible: Mengyao Liu
Overview​
This example demonstrates how to control a CapBot from a BLE central over a custom GATT service called "Robot Control Service". It exists out of two main parts: the firmware for the robot and a python script for the central device. The robot firmware exposes a GATT service that allows to control the robot's wheels and to read its sensor data.
Robot Control Service​
The custom "Robot Control Service" (RCS) has service UUID 00000030-0000-1000-8000-00805f9b34fb.
It exposes the following characteristics:
| Name | UUID | Python API function |
|---|---|---|
| Drive | 00000031-0000-1000-8000-00805f9b34fb | set_motors |
| Speed | 00000032-0000-1000-8000-00805f9b34fb | read_speed |
| Angle | 00000033-0000-1000-8000-00805f9b34fb | read_angle |
| VCap | 00000034-0000-1000-8000-00805f9b34fb | read_voltage |
Drive​
The drive characteristic allows to set a target speed for each motor individually. Furthermore, it requires to send a duration with these target speeds. The firmware on the robot will try to reach these target speeds for duration specified afterwards it will stop them again. A write to this characteristic will overwrite the old target speeds & duration immedeately.
Speed​
The speed characteristic allows the central to read the speed of each motor individually. Positive speeds indicate a forwards movement while negative speeds correspond to a backwards movement.
Angle​
The angle characteristic allows to read the cummulative angle of each motor individually. A positive angle means that the motor's position is currently "forward" compared to were it was at boot, a negative angle means the opposite.
VCap​
The Vcap characteristic reports the current capacitor voltage in mV when read.