Reading PWM signal from a receiver

bulkhead

I would like to interface a 6ch airplane radio with my javelin for a radio control robot. Has anyone done this before? Is there a VP that takes care of this, or do I need to read it in my main loop?

Peter Verkaik

There is no VP for reading pwm signals (only for generating).
So you are required to do it manually in your mainloop.

regards peter

Peter Verkaik

A possible approach is to combine the ADC vp with the CPU.count() method.

pwm signal o

---

+

---

o countPin
······· ··········· |
··········· ······ [noparse][[/noparse]R1]
··············· ··· |·········· +

---

o ADC inPin
·················Ua·+----[noparse][[/noparse]R]----+----[noparse][[/noparse]R]---o ADC outPin
················· · |·········· |
················· ·[noparse][[/noparse]C1]········[noparse][[/noparse]C]
················· · |·········· |
················ ··GND········ GND

The ADC vp measures the average voltage Ua that represents the pwm dutycycle
The count() measures the number of pulses in a given timeperiod (eg. 100msec or so)
From both you can calculate the duration of low and high period of the pwm signal.

Or use two pulseIn() commands, the first measures a high pulse, the second a low pulse.
You must assume then that adjacent pulses do not change, or at least not rapidly.

regards peter

Peter Verkaik

Here is a class that uses the double pulseIn() approach.
I placed it in the folder lib/stamp/core

regards peter