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### Topic: Sensing voltage from the power wires of an RC motor (Read 1 time)previous topic - next topic

#### mahela007

##### Dec 21, 2011, 06:45 pm
Hi.. I'd like to try and rig up an arduino to control the speed of an RC car. I plan to use the cars built-in hardware for the radio communication and then sense the output sent to the motors using the Arduino. The arduino will then use it's own circuity to actually control the motor. (Yes, there's probably a more elegant way to do it  .. but I want to try this method)

The problem is in the fact that the output to the RC motor can change polarity to drive the motor in either direction. How will I be able to sense voltages which switch polarity with the arduino?

#### GoForSmoke

#1
##### Dec 22, 2011, 01:46 am
If the Arduino is controlling the motor in the first place then why you need to sense what you feed it? You should know!

2) http://gammon.com.au/serial
3) http://gammon.com.au/interrupts

#### mahela007

#2
##### Dec 22, 2011, 04:56 am
I want to control the car wirelessly.. i.e Using it's remote.
I'm using the cars circuit to receive the radio signals and output then to the arduino.
The arduino will then used PWM to accelerate the motor gradually, instead of accelerating in one quick jerk. To to this, the arduino has to sense when the remote is sending the appropriate signals.

#### juryben

#3
##### Dec 22, 2011, 07:36 am
You could use a logarithmic equation instead

#### mahela007

#4
##### Dec 22, 2011, 08:29 am
To calculate a value for the power sent to the motor?
...Well, yes. But I need the arduino to sense when the remote sends a signal to the cars' circuit so that it knows when to start the motor.

#5

#### AWOL

#6
##### Dec 22, 2011, 08:53 am
Quote
the problem is in the fact that the output to the RC motor can change polarity to drive the motor in either direction.

So sense the input.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.
I speak for myself, not Arduino.

#7