esklar81:
Valen:
Besides it [a capacitor] will happily conduct the high frequency signal that causes the toggling.Valen,
You seem to be considering a capacitor in series between the microcontroller output and the amplifier control input. That’s most certainly not what I (or, I believe, others) had in mind. To suppress the transients, the capacitor must be in parallel with the amplifier control input. That is, one side of the capacitor is connected to the line between the microcontroller output and the amplifier control input and the other side of the capacitor is connected to ground. As you correctly stated, a capacitor will conduct high frequency signals. That’s exactly what one wants it to do, as those transients will then be sent to ground, rather than the amplifier control input. Sustained outputs from the microcontroller, however, would charge or discharge the capacitor, resulting in a delayed, but less noisy, signal to the amplifier control input.
Ok, you are right. It would dampen the toggling. But not provide a dependable bias voltage that makes the line go either low or high.
Valen:
You need to actively pull it up to Vcc or down to GND.What, precisely, do you mean by “to actively pull”? IOW, what’s the means by which one would to that and how does it differ from pulling “passively”?
I’ve provided a link to the Sparkfun Tutorial about pulling up (and down). With ‘actively’ I meant deliberatly changing the circuit by adding a resistor to either Vcc or Ground. I can understand you got confused since capacitors and resistors are known as passive components.
Valen:
Either use an external resistor or figure out how use the (often built-in) internal pull-up/down resistors of the microcontroller.As the OP’s problem stems (at least putatively) from the startup behavior of the microcontroller, how could the microcontroller fix the problem?
Eric
Since I don’t know exactly which chip is in his Arduino(I know virtually nothing about the arduino), I don’t know for sure. But I guess they are all of the AVR family. As far as I know they all have registers to control the general in-/output pin circuitry, to become inputs or outputs, enable the internal pull up resistor (alteast in the atmega8 there is no pull down resistor built in) and set the H/L-state of if it is an output port. How this is done with the Arduino firmware is something I don’t know. You’ll have to learn that or dig deeper into the datasheet of the used microcontroller.