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Re: Störung auf linker radencoder: entwurfsfehler Kategorie: Pro-Bot128 (von Mansfeld - 23.03.2010 16:34)
Als Antwort auf Störung auf linker radencoder: entwurfsfehler von PepeV - 8.02.2010 22:22
Ich nutze:
> 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).

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Re: Störung auf linker radencoder: entwurfsfehler (von PepeV - 30.03.2010 10:12)
    Re: Störung auf linker radencoder: entwurfsfehler (von Mansfeld - 31.03.2010 15:51)