Hi Thaddy,
thank you for your help, I really appreciate it. But it is not matter of gui. Imagine, there are 5 steppers with encoders. Every one in real time should be read, analysed and then some kind of action has to be done with steppers (stop, go on, back, hold position etc.). There is also voltage circuit in case that an encoder is destroyed? And to the RPi are connected other sensors, next, how to manage with acceler/ deceler. of stepper and so on... That why i decided to separate them from RPi. Simple ATMega8 is very capable of:
1. to generate steps wit accel/decel ramp,
2. to check/count encoder signals,
3. Avr is in some way also autonomous and decides about other processess but always send action's info to RPi,
thus simply RPi sends to avr through I2C few informations as dir, expected encoder's position and other infos. When stepper is in position, avr sends back info. RPi has to collect all datas from all servos/display them/to process datas/ and many other tasks.
----
It sounds interesting about programming avr with FPC. I used to do it with Bascom, you know, there is plenty useful commands that no one has to spend much time to learn how to write code for lcd/i2c/generator and not to mention simulator.