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Linux PWM Gains An Atomic Interface In Linux 4.7

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  • #11
    Originally posted by bregma View Post
    PWM is used for things like stepper motor control. So, for positioning the head of your... uh, how to put it delicately... hard drive. Mmm, no, that sounds rude. It's used in robotics, like changing the angle of your mechanical device. Dang it. Anyway, Linux gets inserted into all kinds of things these days, things that bring hobbyists and professionals alike a great deal of pleasure, so enjoy the new interface.
    I'd also imagine that professional solutions might expect atomic operation. For example if you're controlling lights, would be nice if they didn't accidently blink too fast or too slow or partially when the kernel is processing something. Some motors might not provide smooth operation if the control isn't atomic.

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    • #12
      Originally posted by caligula View Post
      I'd also imagine that professional solutions might expect atomic operation. For example if you're controlling lights, would be nice if they didn't accidently blink too fast or too slow or partially when the kernel is processing something. Some motors might not provide smooth operation if the control isn't atomic.
      Well, the kernel being busy isn't going to affect the pulse width, since that's all done in hardware (you write a width value to a register over the I2C bus, for example). The atomic interface would simply eliminate race conditions between a query and a set operation in the case of a multithreaded controller without having to use a higher-level (and orders of magnitude more expensive) locking operation. The result is a more efficient operation on a small underpowered CPU where cycles, memory, and battery are all at a premium.

      Really, PWM has nothing to do with vibrators or blinkenlights. It's a one-wire data communication protocol using the time domain to communicate digital information.

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      • #13
        Maybe they're writing a linux driver for this old PS2 accessory: http://www.giantbomb.com/trance-vibrator/3000-6/

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