Interactive web site of Télécom ParisTech's ELECINF344/ELECINF381 Robotics and Embedded Systems classes (a.k.a. ROSE, 2012 session).


ChibiOS Crash Course in PWM

The past week I’ve spent more time than I had hoped learning how to use the PWM functionality on the BallE board with the help of ChibiOS. There are a few things that have slowed my progress — for example “TIM3_CH4″ seems to be implemented as Timer 3 Channel “3″ (starting at 0). Not realizing this in order to make the proper 1-off correction consumed the majority of my time.

The other issue I had was implenting the usage of the PWM with one of the board’s blue LEDs. I wasn’t able to use ChibiOS’s “palSetPadMode” function to change the LED to alternative mode 1 on the fly. Instead I found a way to get it working by setting the alternative mode directly in our board.h initialization file. This is not the biggest of issues, seeing as we will most likely never use the LEDs for PWM functionality.

There is still a lot of work to do on implementing the balancing control of BallE. Depending on our progress with getting the H bridges up and functional, I may continue on trying to build a sim environment for testing the control of the motors. The plan is to have a balancing bot by the end of the week… I’m sure this will be a challenge, but I’ll be working hard during the week to have it ready.

Scott Messner


Possibly related posts:

  1. Simulations, Presentation, and Understanding ChibiOS
  2. Challenging week…
  3. Last few days’ work

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