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Topic: Controlling two ESC's through the arduino (Read 1 time) previous topic - next topic

goose722

I am trying to power two brushless DC motors separately through the arduino in order to give a car that I'm working on differential steering.  This is the datasheet for the ESC's I'm using:
http://s195302033.onlinehome.us/CX/esc/duratrax-intellispeed-auto-sport-fwd-rev-manual.pdf

I have the arduino set up with a breadboard to connect to the ESC pins - I have the black wires connected to the Arduino ground and the red Vin wires connected to nothing.  The yellow PWM pins are connected to PWM out pins on the Arduino.  Each ESC has the correct voltage going to it from the battery and is connected to each respective motor correctly as well.

My problem is this:
    When I send a PWM command to one motor(say, for example, I send a forward command to the right motor only), BOTH motors move forward.  The same thing happens when I send a command to the left motor.  I'm not sure what's wrong....

Is the ground on the arduino completing some circuit that makes both ESC's send the same current to the motors?  It's a very simple circuit...I'm not sure what's going on....

johnwasser

An ESC is controlled like a model airplane servo.  Are you using the servo library like in the Sweep tutorial?

http://arduino.cc/en/Tutorial/Sweep

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retrolefty

All common hobby R/C ESC I have seen emulate being controlled just like a servo, so you really should be using a servo library to control them. Trying to use simple PWM with a 20-25 msec period (standard servo refresh period) and using only 1 msec ( 1-2 msec is standard servo pulse width control) of pulse width control leaves you with poor resolution.

Other things to be aware of is if ESC is bidirectional (like for cars) or only one directional control (like airplane props), That drasticaly changes the pulse width that a stopped motor uses. Also check the initial arming sequence procedure as it is most somewhat unique for every model of ESC and so you need to study the user manual carefully as your Arduino code will have to emulate this procedure.

Lefty  

zoomkat

Search the old forum for ESC and you will find a lot of previous discussions on using an ESC with an arduino. One of the key points is generating the "arming" sequence used by ESCs.
Google forum search: Use Google Advanced Search and use Http://forum.arduino.cc/index in the "site or domain:" box.

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