https://github.com/berndporr/alphabot
C++ API to control the functionality of a heavily customised Alphabot with a Raspberry PI
https://github.com/berndporr/alphabot
alphabot pwm robot robotics robotics-programming
Last synced: 5 months ago
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C++ API to control the functionality of a heavily customised Alphabot with a Raspberry PI
- Host: GitHub
- URL: https://github.com/berndporr/alphabot
- Owner: berndporr
- License: apache-2.0
- Created: 2021-04-03T10:03:05.000Z (about 5 years ago)
- Default Branch: main
- Last Pushed: 2022-07-07T22:05:49.000Z (almost 4 years ago)
- Last Synced: 2025-04-08T00:04:54.654Z (about 1 year ago)
- Topics: alphabot, pwm, robot, robotics, robotics-programming
- Language: C++
- Homepage:
- Size: 580 KB
- Stars: 1
- Watchers: 1
- Forks: 3
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# C++ Alphabot API for the Raspberry PI
This page provides instructions how to customise the alphabot so that it's actually
usable for research and it provides a C++ API with proper setters and callbacks.
C++ class to control the basic functionality of a customised Alphabot
(https://www.waveshare.com/wiki/AlphaBot) with a Raspberry PI:
- Motor control (using the Parallax Continuous Rotation Servo)
- Battery voltage
## Hardware mods
### Parallax Continuous Rotation Servos
Throw the original DC motors in the bin and fit the [Parallax Continuous Rotation Servo](https://www.parallax.com/product/parallax-continuous-rotation-servo/) with 90deg brackets. Plug them into the servo ports S1 and S2.
Wire up the pin header:
```
GPIO18 / PWM2 = S1 = Motor left
GPIO19 / PWM3 = S2 = Motor right
```
### Voltage regulator
De-solder the LM2596 and throw it in the bin. It supposed to have a dropout voltage of 1V so that the 7-7.2V from the battery
should be fine but it seems to be more 2V. It's not even recommended by TI who recommend the LMR33630 for new designs.
Replace the LM2596 with a [MGS100505](https://onecall.farnell.com/cosel/mgs100505/dc-dc-converter-5v-2a/dp/4296076). Just glue it upside down on the PCB and run 4 wires to Vin and +5V.
## Software prerequisites
Add to `/boot/firmware/config.txt`:
```
dtoverlay=pwm-2chan
```
and reboot.
Check with:
```
pinctrl -p
```
that you see:
```
12: a3 pd | lo // GPIO18 = PWM0_CHAN2
35: a3 pd | lo // GPIO19 = PWM0_CHAN3
```
which corresponds to the sysfs files:
```
/sys/class/pwm/pwmchip0/pwm2: GPIO18
/sys/class/pwm/pwmchip0/pwm3: GPIO19
```
### libgpiod
The GPIO pins are accessed via the C++ API of the `libgpiod`:
```
apt-get install libgpiod-dev
```
### ncurses
The demo programs below display the sensor
readings with the ncurses library. Install
it with
```
apt-get install libncurses-dev
```
## Building
The built system is `cmake`. Just type:
```
cmake .
make
sudo make install
```
## Usage
The online documentation is here: https://berndporr.github.io/alphabot/
### Start/stop
Start the callback reporting the battery voltage.
```
start()
```
Stop the callback.
```
stop()
```
### Motor speed
Setting the speeds of the left/right wheels:
```
setLeftWheelSpeed(float speed);
setRightWheelSpeed(float speed);
```
where speed is between -1 and +1.
### Callback
There is a callback which reports the battery voltage.
## Demo programs
`testIO` is a simple test program which displays the battery voltage and you can test the motors. It also shows
how the callback is used to display the battery voltage.
`testMotor` ramps up the motor speed and back again.