Can I power 4 Opto ESCs directly from Arduino!

Hi guys!

I'm trying to build a quadcopter using Arduino duemilanov. My question is, can I connect the power wires of my 4 OPTO ESCs to my arduino directly? I would obviously be connecting the power side of the ESC thats connected to the motor, to a separate 3s lipo (not connected to my Arduino).

If it was 4 servos, I wouldn't want to power them directly with Arduino, because they would draw too much current but with opto ESC, it might be ok because the motors will be powered separately by a lipo

Thanks in advance!

baravi: Hi guys!

I'm trying to build a quadcopter using Arduino duemilanov. My question is, can I connect the power wires of my 4 OPTO ESCs to my arduino directly? I would obviously be connecting the power side of the ESC thats connected to the motor, to a separate 3s lipo (not connected to my Arduino).

If it was 4 servos, I wouldn't want to power them directly with Arduino, because they would draw too much current but with opto ESC, it might be ok because the motors will be powered separately by a lipo

Thanks in advance!

Well the common ESCs I've seen and used are not powered by the +5vdc wire but that is rather an output voltage from the ESC that comes from an internal voltage regulator. The ESCs have a higher input voltage used to power the attached motor and that is the voltage that is regulated down to +5vdc. This ESC feature is often called a BEC (battery eliminator circuit) that allows one to power both the motor and anything (like the R/C receiver) that requires +5vdc power thus saving one from having to have two battery packs in the aircraft. It is generally used to provide +5vdc power for the airborne R/C receiver module. You could possibly power an arduino using the ESC's +5vdc output pin by wiring it to the arduino 5V pin.

Lefty

Hi lefty, thank you very much for your reply.

Perhaps, I was not very clear...what I was trying to ask is the opp. to what you replied for, i.e. can I power the 4 ESCs with the Arduino! As I mentioned in the post, my ESCs are all opto...so I won't get 5v voltage from them to power the Arduino.

Cheers!

baravi:
Hi lefty, thank you very much for your reply.

Perhaps, I was not very clear…what I was trying to ask is the opp. to what you replied for, i.e. can I power the 4 ESCs with the Arduino! As I mentioned in the post, my ESCs are all opto…so I won’t get 5v voltage from them to power the Arduino.

Cheers!

An ESC gets it’s operating power from the higher voltage battery that is used to power the motor. Perhaps you are not explaining well what you mean by power. Do you mean control the esc via it’s PWM control input pin, rather then power the esc? A link to your actual ESC datasheet might also be an aid to us.

Lefty

Ya...I think i needed to better explain what exactly I mean :)

My opto ESC (btw its a Turnigy multistar make) has in total 8 connections...2 power connections (thick wires) which I'll be connecting to a 3S Lipo, 3 connections to the brushless motor and another 3 (PWM signal, Vs, Gnd) connections which is what I'm asking about. If it was a normal ESC, I would be getting a +5V from the Vs line, but since my ESC is Opto, I need to provide +5V to the Vs line. So my question is can I provide this +5V to the 4 opto ESCs from the Arduino through its 5V pin (the Arduino would be powered from a separate 2S lipo).

Hope, its clearer now!

Thanks, -baravi

for those who like me dont know

what is an ESC ?

baravi: Ya...I think i needed to better explain what exactly I mean :)

My opto ESC (btw its a Turnigy multistar make) has in total 8 connections...2 power connections (thick wires) which I'll be connecting to a 3S Lipo, 3 connections to the brushless motor and another 3 (PWM signal, Vs, Gnd) connections which is what I'm asking about. If it was a normal ESC, I would be getting a +5V from the Vs line, but since my ESC is Opto, I need to provide +5V to the Vs line. So my question is can I provide this +5V to the 4 opto ESCs from the Arduino through its 5V pin (the Arduino would be powered from a separate 2S lipo).

Hope, its clearer now!

Thanks, -baravi

It would have been much more informative to tell us what the hardware was (full details) in the initial posting - that way we can answer the question you want answered, rather than have a guessing game :)

The Turnigy opto ESCs have no 5V connection - you just supply signal and ground, its just an opto isolator you are talking to.

Hi MarkT...thanks for replying...I tried to provide as many details that came to my mind as possible when I posted my question :)

Anyways, are you sure that the Turnigy Opto ESC have no 5V connection...I saw in some other forum (http://www.rcgroups.com/forums/showthread.php?t=774420&page=2) that the 5V has to be supplied to the ESC.

Cheers!

baravi: Ya...I think i needed to better explain what exactly I mean :)

My opto ESC (btw its a Turnigy multistar make) has in total 8 connections...2 power connections (thick wires) which I'll be connecting to a 3S Lipo, 3 connections to the brushless motor and another 3 (PWM signal, Vs, Gnd) connections which is what I'm asking about. If it was a normal ESC, I would be getting a +5V from the Vs line, but since my ESC is Opto, I need to provide +5V to the Vs line. So my question is can I provide this +5V to the 4 opto ESCs from the Arduino through its 5V pin (the Arduino would be powered from a separate 2S lipo).

Hope, its clearer now!

Without more details on the ESC I can't help you with the hookup you may or may not have to do. A link to the ESC might be helpful. Lefty

Thanks, -baravi

drjiohnsmith: for those who like me dont know

what is an ESC ?

ESC = Electronic Speed Controller.

These devices take a servo type input from a R/C receiver's throttle channel or a microcontroller that allows the ESC to perform the function of a speed controller for an motor attached to the ESC. Many are designed to interface with 3 phase brushless DC motors although some are designed to control simple brushed DC motors. Some allow bidirectional rotation such as forward/reverse for a car model and others allow only single direction for prop rotation for aircraft. From the controllers perspective the ESC looks just like any servo device.

Lefty

baravi: Hi MarkT...thanks for replying...I tried to provide as many details that came to my mind as possible when I posted my question :)

Anyways, are you sure that the Turnigy Opto ESC have no 5V connection...I saw in some other forum (http://www.rcgroups.com/forums/showthread.php?t=774420&page=2) that the 5V has to be supplied to the ESC.

Cheers!

Well looking at the linked picture from the Turnigy ESC you don't have to provide power to the red wire at all as it's a no connection on the ESC. The black ground wire needs to wire to an arduino shield ground pin and a arduino output pin wires to the white wire. http://www.hobbyking.com/hobbyking/store/uploads/1046224823X587173X14.jpg

Lefty

If either +5V or ground were connected to the ESC’s circuitry you’d have no isolation at all, so it
would be utter pointless to use an opto-isolator.

The signal and ground wires go only to the opto-isolator TX side (an LED and series resistor), and no electrical connection
is present

retrolefty: Well looking at the linked picture from the Turnigy ESC you don't have to provide power to the red wire at all as it's a no connection on the ESC. The black ground wire needs to wire to an arduino shield ground pin and a arduino output pin wires to the white wire. http://www.hobbyking.com/hobbyking/store/uploads/1046224823X587173X14.jpg

Lefty

Thank you for the reply lefty but in the above pic the ESC seems to be of a different make (i.e. not Turnigy multistar).

thank you lefty for the ESC answer,

I kept thinking of ESC key, but a speed controller makes much more sense.

drjiohnsmith: thank you lefty for the ESC answer,

I kept thinking of ESC key, but a speed controller makes much more sense.

Well its a poor name in the first place really - they are motor drivers for sensorless BLDC's with "throttle control" rather than speed control - the control characteristics are often poorly characterised and designed to "feel right" when used to pull an RC plane through the skies.

Guys, I posted this question on the hobbyking website and got some interesting replies from a person called 'edfoo' (in the below conversation, Aravind refers to me):

Aravind:

Hi, I'm trying to drive the motor directly from a microcontroller (Arduino) through this ESC (no receiver in my setup). My question is do I need to supply 5V to the ESC from my microcontroller? If the ESC has to be supplied 5V to operate, then how much current does it draw...I mean is it ok to supply 5V from the microcontroller to 4 such opto ESCs and still not burn the microcontroller out?! Thanks in advance!

eddfoo:

You do not need to power the Esc with a 5V supply, it has a 2931 LDO 5v regulator on board to power MCU. You should have a common ground to the arduino so as to interprete the signal levels correctly.

Aravind: Thanks so much for the reply eddfoo! Is there any harm in connecting the 5V red wire to arduino's 5V supply? I ask this because I have a arduino shield which has 3pin servo type connections on it, so if there's no harm in connecting the red wire to Arduino's 5V supply then I can simply attach the ESC 3 pin servo type connection to the Arduino shield without cutting any wires!

eddfoo:

Use a multimeter to check if there is a short between the ground and red wire. If it is open then it should be ok. Maybe to confirm, power up the ESC and check if there is a voltage on the red wire.

Aravind:

Cool...that's a great suggestion...thanks a lot eddfoo! But I wish the data sheet had some info regarding this :(

If you want to go directly to the webpage, then here it is (the above conversation is dated 07/09/13): http://www.hobbyking.com/hobbyking/store/__27776__Turnigy_Multistar_30_Amp_Multi_rotor_Brushless_ESC_2_4S_OPTO_.html

Cheers!