PWM in BeagleBone Blue

Hi All. I am very new to BeagleBone and right now I have BeagleBone Blue with me. I want to generate and test PWM on it. I do not have an oscilloscope so I will try to generate the PWM, test it on one of its on-board LED and the blinking pattern of the LED will confirm the PWM Signal. I need help in following points :

  1. I need the schematic of BeagleBone Blue and a document giving description on how to work on BeagleBone Blue.
  2. I need to understand how to generate PWM in BeagleBone Blue. I work on microcontrollers, so I may need a guidance with reference to the same.
  3. I need help in defining one of the on-board LEDs to be defined as GPIO.

for schematic and some other stuffs:

You can generate using one of the PWM pins or use the PRU for that(for PRU I believe this can help PRU Cookbook).

With the schematic I believe you can find what led is connected to the gpio :slight_smile:

There’s no external connection to the internal LED, so proving the PWM output by an internal LED is complicated.

The better solution is to check the PWM pulse train by the internal eCAP feature, analysing frequency and duty cycle at once. Unfortunately eCAP isn’t well supported by the OS. But there’s a third party library called libpruio. It shipps with an example called pwm_cap doing exactly that test.

Find details at


  • libpruio is developed on BB Black, but also works on BB Blue.
  • The PWM output at P9_21 is GPS_4 on the Blue, but the input at P9_42 is not wired. You’ve to use an other eCAP input at GP0_6 (=P9_28).