Zsolti,
It sounds like there is an issue with bad data getting to the controller. It might be that the RC oscillator is off some casing errors but more likely some data is being sent incorrectly. I would try sending it to another PC and capturing the data. You should be able to then see if there are errors being sent.
Note: at 19200 baud, you should be able to send to 3 services, 80 complete updates per second. BAUD / Bits / CharsPerCMD / servos to control or (19200 / 10 / 8 / 3) = 80. You can also up the baud as high as 57600.
-Glen
↧