Dave °

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9 years, 7 months ago.

LPC1768 - possible to output PPM?

Can I make the LPC1768 output a PPM signal similar to what Radio Control devices use? If not is there a different mbed product that can do it?

3 Answers

good god
7 years, 3 months ago.

https://developer.mbed.org/users/goodgod/code/PPM/

Try it!

David Smart
9 years, 7 months ago.

Hi Dave - you sure can. Take a look at Handbook - PwmOut, and search on pwmout. There are many examples controlling servo's.

Hi David. I want to create PPM not PWM. Or are you saying I can create a PPM frame by chaining together PWM pulses?

posted by Dave ° 29 Sep 2014

I misread this. When I saw radio control, I thought of the 1 to 20 msec pulse width common for servos. You are asking for pulse position modulation or some other technology that embeds a stream of pulses? Then I need to let someone else answer...

posted by David Smart 29 Sep 2014

Yes, Pulse Position Modulation is what I want. It is basically a multiplexing of 8 PWM signals into a single 20msec period. This can be done with a converter board but I would like to do it directly from the mbed if possible. I do appreciate your response!

posted by Dave ° 29 Sep 2014
Robert Spilleboudt
9 years, 7 months ago.

Hi Dave, I made my own RC transmitter "RCCL".
The main documentation is written in french at http://www.robertmagda.be/. A old documentation in englih at https://sites.google.com/site/rcclradio/ ( not up to date)
The programs are documented in english and are at https://bitbucket.org/robertspil/rccl_v4. It did not publish this within the Mbed repositories because I develop offline.
The PPM generator is at RCCL_V4 / hwmbed / timer.cpp
If you need more info , just ask it.

Robert

Hi Robert, I am also trying to make my own transmitter :) Thank you for your response and for the links to your work. I will read through what you have done. My goal is to use an existing futaba RF module and supply it with PPM directly from the mbed.

posted by Dave ° 29 Sep 2014