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--- en:general_information:tutorial:pwm [2015/12/08 12:22] – liedmann
+++ en:general_information:tutorial:pwm [2015/12/08 13:36] – liedmann
@@ Line 10: / Line 10: @@
 PWM devices are listed under **/sys/class/pwm**
-==== enable PWM device ====
+==== export PWM device ====
+<WRAP round important 50%>
+You must export the PWM at first, otherwise the other commands in this tutorial will not work
+</WRAP>
 <code>
 root@MBaXXX:~ cd /sys/class/pwm                                                   // enter pwm folder in sysfs
@@ Line 18: / Line 20: @@
 root@MBaXXX:/sys/your/path/to/pwmchip/pwmchip<pwmchipnr> cd pwm<pwmnr>            // enter exported pwm device folder
 </code>
 ++++ example |
 <code>
@@ Line 24: / Line 27: @@
 root@MBaXXX:/sys/class/pwmchip0 echo 0 > export
 root@MBaXXX:/sys/class/pwnchip0 cd pwm0
+</code>
+++++
+==== set PWM period ====
+<code>
+root@MBaXXX:~ echo <value in nanoseconds> > /sys/class/pwm/pwmchip<pwmchipnr>/pwm<pwmnr>period
+</code>
+++++ example |
+<code>
+root@MBaXXX:~ echo 1000000 > /sys/class/pwm/pwmchip0/pwm0/period
+</code>
+++++
+==== set PWM duty cycle ====
+<WRAP round important 50%>
+The value of duty cycle must be less than the value of pwm period
+</WRAP>
+<code>
+root@MBaXXX:~ echo <value in nanoseconds> > /sys/class/pwm/pwmchip<pwmchipnr>/pwm<pwmnr>duty_cycle
+</code>
+++++ example |
+<code>
+root@MBaXXX:~ echo <value in nanoseconds> > /sys/class/pwm/pwmchip0/pwm0/duty_cycle
+</code>
+++++
+==== change polarity of the PWM signal ====
+<code>
+root@MBaXXX:~ echo "normal" > /sys/class/pwm/pwmchip<pwmchipnr>/pwm<pwmnr>/polarity      // set polarity to normal
+root@MBaXXX:~ echo "inversed" > /sys/class/pwm/pwmchip<pwmchipnr>/pwm<pwmnr>/polarity    // set polarity to inversed
+</code>
+++++ example |
+<code>
+root@MBaXXX:~ echo "normal" > /sys/class/pwm/pwmchip0/pwm0/polarity
+root@MBaXXX:~ echo "inversed" > /sys/class/pwm/pwmchip0/pwm0/polarity
+</code>
+++++
+==== enable PWM ====
+<code>
+root@MBaXXX: echo 1 > /sys/class/pwm/pwmchip<pwmchipnr>/pwm<pwmnr>/enable
+</code>
+++++ example |
+<code>
 root@MBaXXX: echo 1 > /sys/class/pwm/pwmchip0/pwm0/enable
 </code>
 ++++
-root@MBaXXX:
+==== disable PWM ====
+<code>
+root@MBaXXX: echo 0 > /sys/class/pwm/pwmchip<pwmchipnr>/pwm<pwmnr>/enable
+</code>
+++++ example |
+<code>
+root@MBaXXX: echo 0 > /sys/class/pwm/pwmchip0/pwm0/enable
+</code>
+++++