PPM signal decoding and driving 10 RC servo motors

[Guest]

Hi All,

Is there an open source PIC project out there which can do PPM signal
decoding from a RC (Radio Control) transmitter and drive 10 servo motors
with a PIC (PIC18F6680) and a CD4017 decade counter?

Appearetly some how using a CD4017 decade counter with a microcontroller
helps to minimize the processing load on the controller to manage multiple
RC servos. (Do you know how?)

Aaron

 

[jasen]

Hi All,

Is there an open source PIC project out there which can do PPM signal
decoding from a RC (Radio Control) transmitter and drive 10 servo motors
with a PIC (PIC18F6680) and a CD4017 decade counter?

Appearetly some how using a CD4017 decade counter with a microcontroller
helps to minimize the processing load on the controller to manage multiple
RC servos. (Do you know how?)

can't be done, those servos need pwm signals find a micro with enoug pins
for 1 per servo and do the PWM in software (unless you can find a pic with 10
PWM outputs, I know there's an AVR with that many.)

Bye.
Jasen

 

[Mark Harriss]

Hi All,

Is there an open source PIC project out there which can do PPM signal
decoding from a RC (Radio Control) transmitter and drive 10 servo motors
with a PIC (PIC18F6680) and a CD4017 decade counter?

Appearetly some how using a CD4017 decade counter with a microcontroller
helps to minimize the processing load on the controller to manage multiple
RC servos. (Do you know how?)

Aaron

Sounds like the 4017 is used to multiplex the servos, allowing the
PIC to select an individual servo to feed the PWM signal to. I'm
not sure what the servos do when not being fed a PWM signal, maybe
they stay where they are, maybe they go back to zero position.

 

[Ray]

Sounds like the 4017 is used to multiplex the servos, allowing the
PIC to select an individual servo to feed the PWM signal to. I'm
not sure what the servos do when not being fed a PWM signal, maybe
they stay where they are, maybe they go back to zero position.

The pulse stream is used to simply clock the 4017.
Each servo channel is sent sequential in time.
The time between each pulse determines the pulse width sent to each
servo.
A long dwell time between pulses is detected and used to reset the 4017.
This all usually repeats at a 20ms rate.

In other words, the signal sent is pretty much fed direct to the 4017,
no need for a PIC!

If you stop signalling the servo, the motor stays where it is but can be
rotated by the connected device.

If you wish to replace the 4017 with a PIC, that would make more
sense....

Ray