Currently there are no standard PWM driver for the Beagle, though a couple have been proposed  ,  and . You could even do PWM from a shell command by using devmem2 to write to the memory mapped registers from a command line. Here’s another PWM lead. 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. The standard way to interface with the outside world in Linux is through Kernel Drivers.
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If these command cause the SSH connection to close, you may have to get a newer version of Angstrom. There are two linu to do this, the slick way which may not work and the sure way. These MUXes are set at boot time, and must be set when the kernel boots, or in u-boot. Follow the instructions here if you aren’t set up for git.
platform/amx/ti/drivers/ehrpwm.c – kernel/lk – Git at Google
Embedded Linux Class by Ebrpwm A. You may have to set the duty cycle to 0 to change the frequency. The standard way to interface with the outside world in Linux is through Kernel Drivers. I couldn’t set them during kernel boot with the 2. A given pin can have one from as many as eight lines assigned to it. Here’s another PWM lead.
This page was last edited on 31 Mayat The u-boot details are here. We want pin 6. You could even do PWM from a shell command by using devmem2 to write to the memory mapped registers from a command line. If it isn’t you’ll have to recompile the Kernel and u-boot.
EBC Exercise 13 Pulse Width Modulation 3.2
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 Can you guess why? You’ll see something like:.
This says the MUX is presently set on pin 7.
Views Read View source View history. Counting starts on the left with 0. This will show up at ehrpwm1A the 0 maps to A. There are some pins that you can control what they output. Ehr;wm version of the kernel and u-boot that I’ve given you should already be configured to access the PWM pins.
Stick a scope on the pin and see if the ehepwm and duty cycle are right. 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. Navigation menu Personal tools Log in Request account.
Currently there are no standard PWM driver for the Beagle, though a couple have been proposed  and . This is for the 3. Now, linus the settings by browsing to http: Retrieved from ” https: