The fischertechnik construction toy operates the majority of its eletrical components from 9 volt sources. This includes motors and lamps as well as air compressors, valves and fischertechniks own robotics controllers.
The Raspberry Pi on the other hand is operated from a 5 volt USB power source and most of its IOs are further limited to 3.3 volts. A direct connection between fischertechnik components and the Raspberry Pi would either not work at all or even be harmful to the Pi.
The TX-Pi project thus provides several components to integrate the Raspberry Pi into the 9 volt world of fischertechnik.
TX-Pi HAT / ft HAT
The TX-Pi HAT is a commercial hardware add-on for the Raspberry Pi2, Pi3 and Pi4 to power the Pi from regular 9 volt fischertechnik power sources, to interface it with fischertechnik buttons, switches, motors, lamps and similar and to connect it to fischertechnik I²C sensors.
The ftDuino is an Arduino compatible controller designed for fischertechnik. Connected to the TX-Pi gives it 12 fischertechnik compatible inputs and 8 outputs.
I2C breakout and power supply
The I2C breakout and power supply is a DIY project providing a fischertechnik compatible power supply for the Raspberry Pi as well as fischertechnik compatible I²C ports.
The PiPower Module is a very simple DIY module allowing to power the Raspberry Pi from a fischertechnik power source.