PWM - Revision history

JulienB: /* Usage */

2022-02-10T11:30:35Z

‎Usage

JulienB: /* Linux driver installation */

2016-04-15T16:21:09Z

‎Linux driver installation

JulienB: /* Linux driver installation */

2016-04-15T14:50:23Z

‎Linux driver installation

JulienB: /* Hardware */

2016-04-15T14:49:48Z

‎Hardware

JulienB: /* PWM Mode */

2015-05-21T10:34:15Z

‎PWM Mode

JulienB: /* Usage */

2015-05-21T10:25:18Z

‎Usage

JulienB: /* Bash test script */

2015-02-17T15:23:53Z

‎Bash test script

JulienB at 15:22, 17 February 2015

2015-02-17T15:22:40Z

JulienB: /* 2.6 kernel */

2015-02-17T15:21:28Z

‎2.6 kernel

JulienB: /* PWM Mode */

2015-02-17T14:49:21Z

‎PWM Mode

@@ Line 24: / Line 24: @@
 imx-pwm imx-pwm.0: initialized
 </pre>
-* On [[APF28]] with 2.6.35 kernel and on [[APF6]], the PWM driver is builtin so no need to load it before use.
+* On [[APF28]] with 2.6.35 kernel and on [[APF6]] & [[OPOS6UL]], the PWM driver is builtin so no need to load it before use.
 * For the one who plan to use sound, ''/dev/pwm0'' device file should be automatically created.
@@ Line 65: / Line 65: @@
 ||<pre class="apf">
 export PWM_CHIP=pwmchip2    (on APF6Dev)
-export PWM_CHIP=pwmchip0    (on APF9328Dev/APF27Dev/APF51Dev/APF28Dev)
+export PWM_CHIP=pwmchip0    (on APF9328Dev/APF27Dev/APF51Dev/APF28Dev/OPOS6UL)
-export PWM=0    (on APF9328Dev/APF27Dev/APF51Dev/APF6Dev)
+export PWM=0    (on APF9328Dev/APF27Dev/APF51Dev/APF6Dev/OPOS6UL)
 export PWM=4    (on APF28Dev)
 </pre>
 * declare the PWM we will use:
 <pre class="apf">
-  # echo $PWM > /sys/class/pwm/$PWM_CHIP/export
+  # echo ${PWM} > /sys/class/pwm/${PWM_CHIP}/export
 </pre>
 * to have a 100uS period:
 <pre class="apf">
-  # echo 100000 > /sys/class/pwm/$PWM_CHIP/pwm$PWM/period
+  # echo 100000 > /sys/class/pwm/${PWM_CHIP}/pwm${PWM}/period
 </pre>
 * to change duty cycle (for example 50% = 50us of 100us period)
 <pre class="apf">
-  # echo 50000 > /sys/class/pwm/$PWM_CHIP/pwm$PWM/duty_cycle
+  # echo 50000 > /sys/class/pwm/${PWM_CHIP}/pwm${PWM}/duty_cycle
 </pre>
 * to activate PWM:
 <pre class="apf">
-  # echo 1 > /sys/class/pwm/$PWM_CHIP/pwm$PWM/enable
+  # echo 1 > /sys/class/pwm/${PWM_CHIP}/pwm${PWM}/enable
 </pre>
 * to de-activate PWM:
 <pre class="apf">
-  # echo 0 > /sys/class/pwm/$PWM_CHIP/pwm$PWM/enable
+  # echo 0 > /sys/class/pwm/${PWM_CHIP}/pwm${PWM}/enable
 </pre>

@@ Line 14: / Line 14: @@
 i.MX PWM driver is installed by default in standard Armadeus rootfs.
 {{Note|On [[APF51Dev]], as PWM outputs/pins are multiplexed and used as user LED and button by default, you may have to define APF51DEV_USE_LED_AS_PWM or APF51DEV_USE_SWITCH_AS_PWM in Linux sources (''arch/arm/mach-mx5/apf51dev-baseboard.c''), rebuild and reflash the Linux kernel.}}
 == Usage ==

@@ Line 13: / Line 13: @@
 == Linux driver installation ==
 i.MX PWM driver is installed by default in standard Armadeus rootfs.
-{{Note|On [[APF51Dev]], as PWM outputs are multiplexed and used as user LED and button by default, you may have to define APF51DEV_USE_LED_AS_PWM or APF51DEV_USE_SWITCH_AS_PWM in Linux sources (''arch/arm/mach-mx5/apf51dev-baseboard.c''), rebuild and reflash the Linux kernel.}}
+{{Note|On [[APF51Dev]], as PWM outputs/pins are multiplexed and used as user LED and button by default, you may have to define APF51DEV_USE_LED_AS_PWM or APF51DEV_USE_SWITCH_AS_PWM in Linux sources (''arch/arm/mach-mx5/apf51dev-baseboard.c''), rebuild and reflash the Linux kernel.}}
 == Usage ==

@@ Line 9: / Line 9: @@
 ==Hardware==
 PWM pin detail for each APF boards can be found [[Hardware|here]] (under 'BaseBoards' section).
-On [[APF28Dev]] for example, PWM4 is on J10 pin 26.
+On [[APF28Dev]] for example, PWM4 is on connector J10 at pin 26.
 == Linux driver installation ==

@@ Line 62: / Line 62: @@
 ||<pre class="apf">
-export PWM=0    (on APF9328/APF27/APF51)
+export PWM_CHIP=pwmchip2    (on APF6Dev)
 export PWM=4    (on APF28Dev)
 </pre>
 * declare the PWM we will use:
 <pre class="apf">
-  # echo $PWM > /sys/class/pwm/pwmchip0/export
+  # echo $PWM > /sys/class/pwm/$PWM_CHIP/export
 </pre>
 * to have a 100uS period:
 <pre class="apf">
-  # echo 100000 > /sys/class/pwm/pwmchip0/pwm$PWM/period
+  # echo 100000 > /sys/class/pwm/$PWM_CHIP/pwm$PWM/period
 </pre>
 * to change duty cycle (for example 50% = 50us of 100us period)
 <pre class="apf">
-  # echo 50000 > /sys/class/pwm/pwmchip0/pwm$PWM/duty_cycle
+  # echo 50000 > /sys/class/pwm/$PWM_CHIP/pwm$PWM/duty_cycle
 </pre>
 * to activate PWM:
 <pre class="apf">
-  # echo 1 > /sys/class/pwm/pwmchip0/pwm$PWM/enable
+  # echo 1 > /sys/class/pwm/$PWM_CHIP/pwm$PWM/enable
 </pre>
 * to de-activate PWM:
 <pre class="apf">
-  # echo 0 > /sys/class/pwm/pwmchip0/pwm$PWM/enable
+  # echo 0 > /sys/class/pwm/$PWM_CHIP/pwm$PWM/enable
 </pre>
@@ Line 129: / Line 132: @@
 </source>
 === Audio Mode ===

@@ Line 88: / Line 88: @@
 |}
-==== Bash test script ====
+==== Bash test script (2.6 kernels) ====
 * A Bash test script is available given below. Just enter the desired frequency and duty cycle.
 <source lang="Bash">

@@ Line 1: / Line 1: @@
 On this page, you will find usefull informations to configure and use the Pulse Width Modulation (PWM) capabilities of your APF boards.
-The i.MX processor is capable of driving 2 PWM signals:
+The i.MX processors are able to drive 2 types of PWM signals:
-* one is linked to the LCD controller and allows controling the [[BackLight | LCD backlight]] (fixed frequency)
+* one that is linked to the LCD controller and allows controlling the [[BackLight | LCD backlight]] (fixed frequency)
 * the other can be used to generate a PWM signal in several mode:
 ** audio playback

@@ Line 31: / Line 31: @@
 After driver loading, you have access to ''/sys/class/pwm/...'' functionalities:
-====2.6 kernel====
+{| border="1" cellpadding="10" cellspacing="0" summary="PWM usage depending on kernel version" class="wikitable"
-<pre class="apf">
+|- style="background:#efefef;" align="center"
 export PWM=pwm0    (on APF9328/APF27/APF51)
 export PWM=pwm4    (on APF28Dev)
@@ Line 56: / Line 60: @@
   # echo 0 > /sys/class/pwm/$PWM/active
 </pre>
 ==== Bash test script ====