- Expansion for Fischertechnik Robo TX -
Circuit and PCB
The Atmel ATMega8 (U1) controls the whole circuit and interfaces to the Robo TX controller. U2 and U3 are used to drive the 8 outputs. Every output is protected using a self-resetting polymer fuse. The 8 inputs are protected using zener diodes and a current limiting resistor. The power supply is protected from wrong polarity connection by a diode rectifier.
The PCB is populated on both sides. All the connectors (I2C and banana plugs) and some other components are mounted on the bottom side of the PCB. The pictures below show the populated board's top- and bottom side.
Use sockets for all integrated circuits to allow easy changing.
The 2mm banana plugs are mounted onto the BCB using a piece of 1mm diameter wire that is first screwed into the connector. Then the whole connector is mounted onto the PCB.
Mechanical drawings for the hole locations when mounting the circuit into a case are included in the project files.
Communication format and RoboPro library
Details can be found in the project files.