Mimicking DC Motor control

Hello everyone!

Currently I have a small radio receiver (like the one found in toy RC cars) with a DC motor attached to the board. I would like to mimic the radio receiver control with an Arduino BUT I am in need of guidance in measuring the control input the board sends to the DC motor so that I can record and program this.

I have already considered using the RC input from the radio receiver rather than the DC motor but I have found that this is an integrated portion of the board so my only hope is reading the DC motor.

First attached is a simple sketch of what the toy looks like.

Second attached is my desired.
What I know is wrong with my desired sketch is that the current is too high for Arduino to handle so I planned on placing a resister there. My plan is to use the RC radio to send input to the receiver and read the inputs from the connections from the DC motor through serial using the Arduino. I am having some major issues with getting the DC motor connections to the Arduino though.

A DC motor is not a serial device. It is not even a digital device.

Does the DC motor run in both directions or just one direction?

If one direction, the receiver is probably providing a PWM signal (like the Arduino's "analogWrite()") to a transistor driving the motor. If two directions there are a few transistors (four or more) forming an H-Bridge. One signal from the receiver will set the direction and one PWM signal will set the speed.

Of course that it is not serial. The serial read is through the Arduino terminal via USB. The motor runs in both directions.

mangodown: The motor runs in both directions.

You can control the motor with an Arduino Motor Shield (eliminating the receiver board). If the receiver has discrete transistors you can probably drive them with the Arduino in place of the receiver part of the circuit. You just need to figure out which pin of the IC is Direction and which is Speed. They will be two lines from the receiver to the cluster of transistors connected to the motor wires.

If you can explain what you actually want to do, then you will probably get some useful advice.

The phrases "mimic the radio receiver control" and "mimicking DC motor control" are meaningless to me, and probably to others.

I apologize for lack of detail. I just did not want an over complicated explanation.

The issue here is that I cannot eliminate the receiver board. The project will work on two modes. Arduino control and RC control. The purpose is to accept transmissions to the receiver until switching to Arduino control mode. Here is the receiver I am using exactly.

http://www.horizonhobby.com/receiver-esc-dsm2-x-ember--champ--j-3-pkz3352

This is why I am working with the red and blue wires coming from the motors.

What I would like to do exactly is to be able to "listen" to those red and blue wires into Arduino so that I can determine what output I would need to create or mimic such that I can send similar signals to the motor without the need of the receiver when switching to Arduino control mode.

The link you provided is completely devoid of information, except that the picture shows two motors.

If you wish to duplicate the signals sent to the motor(s), you will need to use an oscilloscope to determine exactly what they are. As johnwasser said above, there is probably an H-bridge or two, and if motor speed is controllable, the output will almost certainly be pulse width modulated (PWM).

You MUST also be aware that, if the motor can run fowards and backwards the little receiver will be sending a negative voltage to the motor for one direction. You CANNOT feed a negative voltage into an Arduino - you will destroy it. The voltages going into an Arduino must be between 0v and 5v.

What you are trying to do is far from trivial.

...R

jremington: The link you provided is completely devoid of information, except that the picture shows two motors.

I am fully aware of this. Notice that is the manufacturer, meaning the lack of information is what lead me here.

Robin2, Thank you for the useful information. I didn't realize the difficulty of listening to the DC motor.

The receiver board appears to have two linear servos on it. That means it not only has two H-Bridge motor drivers but also two analog inputs. Based on the small size of the motors it seems likely to me that the motor drivers are integrated into the receiver chip. This is going to be a major bitch to control with an Arduino and even worse to switch control between the integrated receiver chip and your Arduino.

From the description on the ParkZone site it appears this receiver has a built-in 10 Amp ESC for a Brushless DC motor. Did you want to control the main motor as well as the two liner servos?

The only way I can see of getting the control you want is to replace this integrated receiver, ESC, and servos with a separate receiver, separate ESC, and separate servos. Then you can connect the Arduino between the receiver and the other devices and have the Arduino pass-through the signal when you want manual control.

johnwasser: The only way I can see of getting the control you want is to replace this integrated receiver, ESC, and servos with a separate receiver, separate ESC, and separate servos. Then you can connect the Arduino between the receiver and the other devices and have the Arduino pass-through the signal when you want manual control.

Agreed, I am dropping the integrated board and going with this plan.

Perfectly doable also. Thank you Johnwasser!