Logic level for PWM, kernel 4.1?

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#1

Hi,

Is there any way to configure logic level for PWM on BeagleBone Black/Green? I want that in duty cycle, the level of pinout is 0V, instead of 3.3V.

I’m using Debian 8 with kernel 4.1.

#2

you are not making sense.

pwm pin low - 0v high = 3.3 v

#3

What I want is, after “reset”, the servo motor is supposed to be off, the pin is 3.3V, and when PWM starts, the servo is supposed to be started, the pin is 0V.

#4

Stick an inverter in there.

Regards,

#5

Hi Robert,

So there is no way to config the pin? I want the pin to be 0V when PWM is working, because I want to reduce the power drain from my BeagleBone board to feed the PWM pin. It is similar to why we have GPIO at 0V to turn on the LED.

#6

you will need an external inverting buffer

#7

Read the datasheet. It will tell you the state of the pin after reset, before the SW has run.

Gerald

#8

I don't really care the status in short moment. The reason behind my
question is:

"
​I want the pin to be 0V when PWM is working, because I want to reduce the
power drain from my BeagleBone board to feed the PWM pin. It is similar to
why we have GPIO at 0V to turn on the LED."

It will be good if you can point me where to read in the datasheet. I feel
difficulty reading the whole document.

#9

Do a PDF search for the pin number.

Gerald

#10

If you don’t care about the initial state and when Linux is booting, why don’t you just invert
the duty cycle in software? That would effectively invert the pin polarity.
— Graham