Kernel Module to support pwm for the sun4i (and others???)
Creates a sysfs structure like the following:
-- pwm-sunxi
|
+----pwmX
|
+---duty
+---duty_percent
+---period
+---polarity
+---pulse
+---pin
+---run
Period values can be a bit confusing - I have a google spreadsheet that you can use to explore what will happen with different period and duty values
Allwinner A10 Prescale explorer
-
period (r/w)
period that makes up a cycle. Can be expressed as hz, khz, ms, or us. Whole numbers only.Examples:
echo 10hz > /sys/class/pwm-sunxi/pwm0/period
echo 1khz > /sys/class/pwm-sunxi/pwm0/period
echo 100ms > /sys/class/pwm-sunxi/pwm0/period
echo 100us > /sys/class/pwm-sunxi/pwm0/period
echo 150khz > /sys/class/pwm-sunxi/pwm0/period
-
duty (r/w)
portion of the period above that is "active" or on. Same units as above
-
duty_percent (r/w)
duty expressed as a percentage. Whole numbers only
echo 50 > /sys/class/pwm-sunxi/pwm0/duty_percent
-
polarity(r/w)
polarity of the pin during the duty portion. 1 = high, 0 = low during
-
pulse (r/w)
Output one pulse at the specified period and duty
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pin (ro)
Name of the A10 pin this pwm outputs on. This is hardwired and informational only. Example: PB2
-
run (r/w) Enable the PWM with the previously set parameters. Example:
echo 1 > /sys/class/pwm-sunxi/pwm0/run
echo 0 > /sys/class/pwm-sunxi/pwm0/run