EHRPWM LINUX DRIVER

In a previous exercise EBC Exercise 11 gpio Polling and Interrupts you saw how to use the gpio to produce a square wave out using a C program and sysfs. There are some pins that you can control what they output. Stick a scope on the pin and see if the frequency and duty cycle are right. The standard way to interface with the outside world in Linux is through Kernel Drivers. Follow the instructions here if you aren't set up for git. In this exercise you will learn how to use the Beagle's pulse width modulation pwm hardware using the sysfs interface and also learn about pin multiplexing pin mux on the way.

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Stick a scope on the pin and see if the frequency and duty cycle are right. Can you guess why? The version of the kernel and u-boot that I've given you should already be configured to access the PWM pins.

AMx PWM Driver's Guide - Texas Instruments Wiki

Views Read View source View history. Currently there are no standard PWM driver for the Beagle, though a couple have been proposed [1][2] and [3]. The DM has 11 general purpose timers, 4 of which gpt8-gpt11 can be brought out of the chip and used for pulse width modulation DM TRM page In this exercise you will learn how to use the Beagle's pulse width linuux pwm hardware using the sysfs interface and also learn about pin multiplexing pin mux on the way.

This page was last edited on 31 Mayat I couldn't set them during kernel boot with the 2. Although this approach works, it is really transitional until a standard can be established. The u-boot details are here.

ehr;wm The standard way to interface with the outside world in Linux is through Kernel Drivers. A given pin can have one from as many as eight lines assigned to it.

There are some pins that you can control what they output. We want pin 6. Now, check the settings by browsing to http: In a previous exercise EBC Exercise 11 gpio Polling and Interrupts you saw how to use the gpio to produce a square wave out using a C program lniux sysfs.

You may have to set the duty cycle to 0 to change the frequency.

Retrieved from " https: You'll see something like:. Embedded Linux Class by Mark A.

EBC Exercise 13 Pulse Width Modulation 3.2

If it isn't you'll have to recompile the Kernel and u-boot. You could even do PWM from a shell command by using devmem2 to write to the memory mapped registers from a command line. I was able to get a 1.

Here's another PWM lead. Privacy policy About eLinux. How do you shrpwm which one to change? This will show up at ehrpwm1A the 0 maps to A. There are two ways to do this, the slick way which may not work and the sure way.

Navigation menu Personal tools Log in Request account. Try changing the frequency and duty cycle. What's the highest frequency you can get? Follow the instructions here if you aren't set up for git. Counting starts on the left with 0. These MUXes are set at boot time, and must be set when the kernel boots, or in u-boot. This says the MUX is presently set on pin 7. This is for the 3.