Follow the instructions here if you aren’t set up for git. You may have to set the duty cycle to 0 to change the frequency. Counting starts on the left with 0. Currently there are no standard PWM driver for the Beagle, though a couple have been proposed  ,  and . Try changing the frequency and duty cycle.
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Retrieved from ” https: In this exercise you will learn how to ehrpqm the Beagle’s pulse width modulation pwm hardware using the sysfs interface and also learn about pin multiplexing pin mux on the way.
You may have to set the duty cycle to 0 to change the frequency. Stick a scope on the pin and see if the frequency and duty cycle are right. This will show up at ehrpwm1A the 0 maps to A.
Counting starts on the left with 0. I couldn’t set lknux during kernel boot with the 2. You could even do PWM from a shell command by using devmem2 to write to the memory mapped registers from a command line.
EBC Exercise 13 Pulse Width Modulation 3.2
The u-boot details are here. Now, check the settings by browsing to http: Views Read View source View history. I was able to get a 1. This says the MUX is presently set on pin 7.
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 .
If these command cause the SSH connection to close, you may have to get a newer version of Angstrom. Follow the instructions here if you aren’t set up lijux git.
A given pin can have one from as many as eight lines assigned to it. 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 Try changing the frequency and duty cycle.
We want pin 6. Although this approach works, it is really transitional until a standard can be established. Here’s another PWM lead. Embedded Linux Class by Mark A. These MUXes are set at boot time, and must be set when the kernel boots, or in u-boot. Can you guess why? If it isn’t you’ll have to recompile the Kernel and u-boot.
What’s the highest frequency you can get? 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.
platform/amx/ti/drivers/ehrpwm.c – kernel/lk – Git at Google
The standard way to interface with the outside world in Linux is through Kernel Drivers. This is for the 3. The version of the kernel and u-boot that I’ve given you should already be configured to access the PWM pins.