# How to connect a 2.4ghz 4ch RC receiver to a brushed dc motor controller?

I currently have a 36vbdc 800w motor connected to a 36v 800w motor speed controller (similar to what they use to control ebikes) just like this one: https://aws.robu.in/wp-content/uploads/2016/02/919811586_739.jpg (I don't know how to upload pics or wiring diagrams to my question or I would).

I would like to use a 2.4ghz 4ch RC remote transmitter and receiver to control the motor speed instead of the wired throttle I currently use, which is a 3pin hall sensor (+5v, Gnd, sensor) twist throttle.

Is there any way to connect the RC receiver to the motor controller to use the remote transmitter to control motor speed? How would I go about this?

I believe both the RC signal and the hall sensor are PWM, but do I need a receiver board to interface with the RC receiver and the motor controller?

Would I need to implement arduino into the equation?

• Tip: 'GHz' or gigahertz, 'V' or volt, 'W' or watt. Capitals matter. Dec 1, 2021 at 11:20

RC servo signal is a 1-2ms pulse with repetition period of ~20ms. Ebike controllers generally accept an analog voltage between 0-5V (with 1V=off and 4V = full throttle). You will need an interface to convert from one to the other. Possible solutions range from purely mechanical (servo attached to a potentiometer) to an MCU with D/A converter.

The Arduino can measure servo pulse width with pulseIn() and produce an 'analog' output with analogWrite(). On most Arduinos the analog outputs are actually 0-100% PWM at ~490Hz. To convert this to true analog you need a low pass filter or integrator which averages the pulses, eg. this simple RC filter:-

simulate this circuit – Schematic created using CircuitLab

A side effect of integrating the PWM pulses is slower throttle response. Here is the result of simulating the above circuit in LTspice, with a 0.5 second 50% throttle burst:-

• Bruce, But arduino can't take that much current... Dec 6, 2017 at 6:26
• Bruce, Also, where is the RC receiver in your schematic? Dec 6, 2017 at 6:27
• "But arduino can't take that much current..." - that's OK, the motor controller doesn't take that much current on its throttle input. Dec 6, 2017 at 7:25
• "where is the RC receiver in your schematic" - sorry the receiver connections seemed so obvious I didn't bother putting them in the diagram. Each channel has 3 pins: Signal, +5V, and Ground. Connect +5V and Ground to same on Arduino. Connect Signal to the Arduino pin you are reading with pulseIn(). Here's an example:- stormgate.org/tricopter/receivercircuit.jpg Dec 6, 2017 at 7:44
• Bruce, sorry I'm new to all of this so I apologize if my questions seem obvious or remedial. Having said that, I'm still a little confused... So the 3 hall sensor (throttle) wires from the motor controller (instead of connecting to the twist throttle) would connect to the arduino, and the 3 pins from the RC receiver would also connect to the arduino? Dec 7, 2017 at 10:33