sfz-pitechcar 0.1.0

Control software for remote Fischertechnik Maker Car with SFZ PCB.

SFZ-PiTechCar (Python Package)

Python-based software for controlling a Fischertechnik Maker Kit car via a custom-built PCB and Raspberry Pi. Provides precise motor control (forward/backward) and steering via a servo. Supports the official 8.4V Fischertechnik NiMH battery. Additional sensors can be connected using stemmaQT connectors and controlled with CircuitPython-based libraries.

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Required Hardware

	Fischertechnik Maker Kit Car The base platform for the PiTech Car project, including chassis, wheels, motors, and steering mechanism.
	Fischertechnik 8.4V NiMH Battery Provides reliable power for the PiTech Car HAT+, motors, servo, and Raspberry Pi. Includes a standard charger. Note: Higher-power Raspberry Pi models may draw too much current, causing undervoltage warnings or preventing the Raspberry Pi from starting. It is recommended to use a Raspberry Pi 3 or Raspberry Pi 3A+.
	Raspberry Pi 3A+ Serves as the main controller for the car, running the Python software and handling communication with the PiTech Car HAT+. Other Raspberry Pi models (e.g., 3B+, 4) are also compatible.
	Custom-Built PiTech Car HAT+, Falko Schmidt, SFZ, 2025 Handles motor control (forward/backward) and steering via servo, interfaces with the battery, and provides stemmaQT connectors for additional sensors. Designed specifically to integrate seamlessly with the Python control software and Raspberry Pi.
	Pi Hut Controller (Remote Control) Used to control the PiTech Car. Interfaces with the Raspberry Pi over USB, allowing the user to drive, steer, and send commands remotely. Only the joysticks are used; the buttons can be assigned for custom functionality.

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Software Prerequisites

Installation of 'Blinka'

⚠️ This software only works on Raspberry Pi systems!

The Python control software requires several CircuitPython libraries to interface with sensors. On Raspberry Pi, these libraries rely on the Blinka compatibility layer from Adafruit. To install Blinka, run the following commands:

cd ~
pip3 install --upgrade adafruit-python-shell
wget https://raw.githubusercontent.com/adafruit/Raspberry-Pi-Installer-Scripts/master/raspi-blinka.py
sudo -E env PATH=$PATH python3 raspi-blinka.py

Installation of 'Python 3.7'

⚠️ This software requires Python 3.7!

The recommended setup is to use a virtual environment based on Python 3.7. The reason is that the approxeng.input library depends on evdev==1.6.1, which is not compatible with newer Python versions. The steps below install Python 3.7 without changing the system’s default Python version on Raspberry Pi:

sudo apt update
sudo apt upgrade
sudo apt install build-essential zlib1g-dev libncurses5-dev libgdbm-dev libnss3-dev libssl-dev libreadline-dev libffi-dev wget
cd /tmp
wget https://www.python.org/ftp/python/3.7.9/Python-3.7.9.tgz
tar -xvf Python-3.7.9.tgz
cd Python-3.7.9
./configure --enable-optimizations
make -j 4
sudo make altinstall

Create and activate a virtual environment

After Python 3.7 is installed, create a virtual environment and activate it:

python3.7 -m venv ftberry_python_venv
source ftberry_python_venv/bin/activate

Once activated, all Python packages will be installed only inside this environment.

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Software Installation

Before installing the software, make sure the Python virtual environment is activated. Then install the software by running:

pip install sfz-pitechcar

All required dependencies listed below will be installed automatically.

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Pre-Usage

Before running the software, you need to identify and profile the controller you are using. The Python library ApproxEng Input is used for this purpose. Follow the official profiling instructions here:

ApproxEng Input Profiling Guide

After profiling, move the generated YAML file into the correct directory as described in the documentation. Once this is done, your controller is ready for use with the PiTech Car software.

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Usage

Open a terminal and create a Python file in your home directory:

cd ~
nano pitech_car.py

Paste the following code into pitech_car.py:

from pitechcar.car import PiTechCar

car = PiTechCar()
car.run()

Notes:

• car.run() starts the main control loop.
• Controller disconnects and cleanup are handled automatically for safety.

Auto-Start on boot

If you want PiTechCar to start automatically, first create a bash script that activates your virtual environment and starts the Python program:

cd ~
nano pitechcar_controller.sh

Add the following content (adjust the virtual environment path if needed) and make it executable:

#!/bin/bash
source ~/ftberry_python_venv/bin/activate
python3 ~/pitech_car.py
sudo chmod +x ~/pitechcar_controller.sh

Next, create a service file:

sudo nano /etc/systemd/system/pitechcar_controller.service

Add the following content (replace USERNAME with your actual username):

[Unit]
Description=PiTechCar Controller
After=usb-devices.target
Wants=usb-devices.target

[Service]
Type=simple
User=USERNAME
WorkingDirectory=/home/USERNAME
ExecStart=/bin/bash /home/USERNAME/pitechcar_controller.sh
Restart=on-failure
StandardOutput=journal
StandardError=journal

[Install]
WantedBy=multi-user.target

Enable the service to start on boot:

sudo systemctl enable pitechcar_controller.service

Start the service immediately (optional, without reboot):

sudo systemctl start pitechcar_controller.service

Your PiTechCar controller should now run automatically on boot.

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Python Package Dependencies

ℹ️ All dependencies listed here are automatically installed with the package.

• ApproxEng Input 2.6.4 (Linux only)
  Provides joystick and controller input handling.

• Adafruit Python Shell 1.11.1
  Helps run Python scripts on the Raspberry Pi via the shell, required for Blinka.

• Adafruit CircuitPython PCA9685 3.4.20
  Controls PCA9685 PWM controllers.

• Adafruit CircuitPython ServoKit 1.3.22
  Provides an easy interface to control multiple servos via ServoKit.

• Adafruit CircuitPython MCP3xxx 1.5.0
  Reads analog sensors via MCP3008/MCP3208 ADC chips.

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Project Structure

sfz-pitechcar/
├── assets/              # Images and diagrams for README
├── scripts/             # Example scripts
│   └── run_car.py       # Main script to start the PiTech Car
├── src/pitechcar/       # Python package
│   ├── hardware/        # Low-level hardware modules (motors, sensors, battery)
│   └── modules/         # Higher-level control modules (motor, battery, WiFi)
├── README.md
├── pyproject.toml

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Contributing

Contributions are welcome! To contribute, please fork the repository, make your changes, and submit a merge request. For major changes or feature additions, consider opening an issue first to discuss your ideas.

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License

This project is licensed under the BSD-3-Clause License. © 2026 Falko Schmidt.