Kommentar: Einfügen von HTML im Kommentar: Link einfügen: <a href="LINKURL" target="_blank">LINKTITEL</a> Bild einfügen: <img src="BILDURL"> Text formatieren: <b>fetter Text</b> <i>kursiver Text</i> <u>unterstrichener Text</u> Kombinationen sind auch möglich z.B.: <b><i>fetter & kursiver Text</i></b> C Quellcode formatieren: <code>Quellcode</code> BASIC Quellcode formatieren: <basic>Quellcode</basic> (Innerhalb eines Quellcodeabschnitts ist kein html möglich.) Wichtig: Bitte mache Zeilenumbrüche, bevor Du am rechten Rand des Eingabefeldes ankommst ! -> I > > > > The outputs of Timer T1 PWM X (X1_3 / OC1A and X1_2 / OC1B) couse interference on the collector > > > > of the left wheel encoder phototransistor T3, which is connected to input port X1_9 / INT7. This is > > > > coused by a design error on the printed circuit board of the drive unit. > > > > > > > > On the top side of that board the wire that runs from T3 to CON2 runs very close and parallel to the two > > > > lines on the bottom side that carry the PWM signals for the motors. The result is that INT7 (left counter) > > > > receives extra pulses from interference and the robot will not drive strait at low speeds. (At low speeds > > > > the pulses from the phototransistors are less steep and therefore more sensitive to interference.) > > > > > > > > I solved the problem by disconnecting the printed wire from T3 to CON2 (cutting it near T3 and CON2) > > > > and replacing it with a shielded wire. But hopefully the designers will find a more elegant solution by > > > > altering the printed circuit board. > > > > > > Hi Pepe, > > > thats a very interesting report. U. Sommer recommends in his book to > > > insert two Schmitt-Triggers between collector of T3 / T4 and the > > > Prozessor pins X1_9 and X1_10. > > > How did you GND the shield: On both ends, sender end or receiver end? > > > (I don't own a scope, I can't watch the result). > > > Regards > > > Fred > > > > > > > Hi Fred, > > > > I grounded only one end of the shield to prevent 'ground loops'. I chose the receiver end but I don't > > think it matters very much. > > Maybe you want to read my contribution 'Improving the wheel encoders' too. Together with the above > > this really is a big improvement and you will not need the Schmitt-Triggers anymore. > > > > Regards, > > Pepe > > Hi Pepe, > thanks, I will give it a try. > Regards > Fred
