Found it. You were right: The servo expected to get a different
pulse-width, not a different duty cycle to control its speed and direction.
I'm used to the other kind.
And the clue was there all along: The servo ran when the button was
unchecked, not when it was checked. It was failing when the duty cycle was
1.0 because there was no wave for the servo to read a frequency off of at
all.
The new, working code, that runs no matter what:
if (button_.isChecked()) {
pwm.setPulseWidth(900);
} else {
pwm.setPulseWidth(2000);
}
Now that runs even if I replace the button_.isChecked with (false) or
another trigger.
Thanks!
On Thursday, September 25, 2014 1:51:15 PM UTC-7, Sam Brown wrote:
>
> Yep. Note that the waveform doesn't change between the working example and
> the non-working example. The only difference in the code is in when the
> if-then statement triggers the motor: In the working example, it triggers
> off the button being toggled. In the non-working example, the if clause is
> set to false, so the motor should run always. (Yet doesn't run at all.)
>
> To be sure this was the line that killed it, I've toggled that single line
> of code back and forth. When I start with:
> if(button_.isChecked()) ...
> ...it works. But when I change that to
> if(false) ...
> ...it won't run the motor.
>
> I've swapped it back and forth repeatedly, making just that one change, to
> be sure that was the key.
>
> One thought that occurred to me, is maybe keying it off the button forces
> it to only send the pwm command when the IOIO is plugged in. Since the
> if(false) triggers all the time, I can imagine that it's sending the
> command to the non-existent IOIO, when the program first runs (while it's
> being loaded from Eclipse) and then doesn't send the command again, when
> the android phone hosting the program is unplugged from the computer and
> then plugged into the IOIO.
>
>
>
>
>
> On Thursday, September 25, 2014 10:58:01 AM UTC-7, Ytai wrote:
>>
>> Are you sure this is the waveform that the servo expects? Typical hobby
>> servos require a 50Hz PWM input, where the pulse width varies between
>> 1-2ms. See IOIOSimpleApp as an example.
>> On Sep 25, 2014 10:48 AM, "Sam Brown" <[email protected]> wrote:
>>
>>> I started an IOIO app from the HelloIOIO sample, and converted the "turn
>>> the light on or off" button to a "send a PWM signal" button so it could
>>> drive a servomotor.
>>>
>>> With minimal changes, the code works beautifully: (Excerpt from void
>>> loop())
>>>
>>> if (button_.isChecked()) {
>>> pwm.setDutyCycle(0.5f); // Don't spin.
>>> } else {
>>> pwm.setDutyCycle(1.0f); // Do spin.
>>> }
>>>
>>> But once I no longer key the pwm off the button, it fails. Making this
>>> trivial change, which I would expect to spin the motor always, prevents the
>>> motor from spinning ever:
>>>
>>> if (false) {
>>> pwm.setDutyCycle(0.5f); // Never reach here. Never stop.
>>> } else {
>>> pwm.setDutyCycle(1.0f); // Always choose this. Always spin.
>>> }
>>>
>>> Can anyone point out what I'm missing?
>>>
>>> - - - - - - - - - - - -
>>>
>>> Originally posted on StackOverflow, here
>>> <http://stackoverflow.com/questions/26032111/pwm-on-ioio-works-when-tied-to-a-button-fails-always-when-independent-of-button>
>>> .
>>>
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>>
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