Looks like you were left hanging on this one, or did you get your answer?
If not, if you read all this you'll not only find your answer, but better understand whats being said to store away in your future knowledge data base...
I'm new to all this RC stuff, but not electronics. I ran across your post just looking for any info and tips I could find for the Futaba 6EX, and while your post isn't helping me any, maybe I can help you since it looks like no one is able to answer your question. Or at least help someone else trying to learn this stuff and get a better understanding.
Futaba gave you a great answer, it's this other company that's not doing so well.
I'm going to try to explain this so you understand, which will help you better. Its not that complicated, you just need to be able to picture it in your mind. I don't think I can post pictures here or I'd even draw you up so diagrams.
Lets start where Futaba did in their response to you...
"The signal is a square pulse"
What they are referring to here, or how this term came to name, is how the signal looks when viewed on an Oscilloscope (picture the device your likely more familiar with, the monitor you see in hospital rooms with the up and down line going across the screen, when the line goes "flat", straight across, you know from watching TV this means your dead. Same in electronics when viewed on the O-scope, the frequency of the signal is viewed though instead of your heart beat (the line going up and down.
A square pulse is for the most part considered to be a DC digital signal (though you can chop an AC analog signal to recreate a square pulse by using capacitors and diodes). Its basically an ON or OFF pulse. So if you were to view it on your Oscilloscope you would see the line moving straight up a short distance (power on or DC positive), to the right a short distance (length it moves right is your "pulse width" which Futaba is referring to by "1.0-2.0 mS wide"), the pulse (or voltage for simplicity) goes back to off, the line you see on the scope goes straight down. The voltage is off the same time it is on so your line then travels this same distance still to the right before it repeats the voltage, bringing your line back up, at peak voltage the line then moves to the right again. Looking something like this...
Square Wave Signal:
(The line is starting at 0, off, in the center of your scope)
It probably sounds complicated when you read it stated as only...
"The signal is a square pulse of 1.0-2.0 mS wide"
But if you can picture in your mind what this looks like, and know what they mean as explained to you here you will see its actually not that complicated. The "mS" is just the length in time that this signal, in this case, is true on or true off. Its represented by what you view on your scope as the Horizontal lines (the vertical lines remember are on / off).
You could also picture this by you simply flipping a light switch on your wall on and off. You flip the switch on, the line goes up equal to your house voltage where it peaks, the length of time you leave that light on is the distance the line then moves horizontal to the right. When you shut the switch off, the line as viewed on the scope would drop back down to zero. The time you leave it off is the time your dropped line travels further right at zero, before you flip the switch back on and the line goes back up.
Flipping the light switch on your wall off and on at a rate of 1.0 - 2.0 mS would be really fast, you'd likely be closer to 1 - 2 Seconds.
Next, the part that seems to be causing your confusion, is as simple as it sounds...
"that repeats every 20 mS or so"
Maybe you could think of that as a square wave within a square wave. Your sending (transmitting) say a 1.0mS pulse out for 20mS (length of time), then nothing for 20mS, then the 1.0mS pulse is repeated again (this continues as long as you have that switch on the control in the on position).
This is where he is confusing you by talking about servos instead of what your specifically interested in (likely the result of a cut and paste response), which I'm only guessing is not a servo but some type of control circuit...
"The width of the pulse determines the position of the servo"
So he's telling you the length of time that line you see on your O-scope is traveling to the right gets interpreted by the servo so it can determine where center is, and the stops in both directions.
"with 1.5 mS as the nominal center"
The above seemed to slightly confuse whoodie here responding to you when they stated...
"the width of the pulse at full left throw is 1.0 ms. At full right, 2.0 ms. At center, 1.5 ms".
He may have just been simplifying for you but this is inaccurate, remember, the 6EX allows you to adjust your end stops. It's full capability as stated to you by Futaba is 1.0 to 2.0 mS. This would already have you at your limits with no space for adjustment of the stop point. They are actually slightly over extending the time to give you room. It will typically be more like 1.5mS center (90deg), 1.25mS 0deg, 1.75mS 180deg.
So if the controller is repeatedly sending a 1.75mS wave pulse to the servo the servo holds in the 180deg position. The length of time this repeats is so the servo knows when your still telling it what to do and have not gone into off. As long as you are not touching your steering the repeated pulse being transmitted for control is 1.5mS (this is why your wheels will straighten up when you power on, or at least turn to where you have the trim set for the 1.5mS center position).
These wave lengths are pretty much the standard for small servos, that's why Coldnorth is trying to tell you what he has...
"but I don't believe you will ever find a servo that uses anywhere near a 5ms to 20ms pulse width. That implies they are building a product that can't be used with 99.99% of the radios out there, which makes no sense."
I guess they could manufacture a servo to respond how ever the designer wanted it, but when I was shopping for a new steering servo the specs on all of them range at 1.0 to 2.0 mS for positioning, or, aka the standard.
At the heart of everyones confusion here is only seeing that word "width" in there and your leaving the the other word which makes a difference, pulse width and band width in this reference are 2 different terms, just like "red apple" and "red car". They both have the word red, but are 2 different things.
By bandwidth he is referring to the time the cycle repeats, not the length of the pulse width.
"It is suitable for the transmitter which band width is between 5 to 20 ms."
The 6EX has in this reference a "bandwidth" (signal repeat) of 20mS so it will work. The reason 3racing is specifying this is because I noticed when I was shopping for my Transmitter there are some (older FM ones mainly I believe) that only repeat every 50mS which would not work. This 3racing device will be looking for the signal every 5-20mS to hold on or probably think you have turned it off or possibly go into a sleep mode.
The only thing in all of this that actually makes no sense is why this 3racing company would restrict this to only a 5-20mS range when there are control devices in the targeted market that repeat slower than this. You would think they would just make the range open to handle 5-50mS. I know nothing about this product or this company beyond what I read in this very post, but in other devices I'm familiar with this is usually an indication that the control device being used is not specifically manufactured just for this application. Instead its likely either being purchased off the shelf as a universal device, or being borrowed from another more specific device.
With all that said, I need to get back to finding my answer I'm searching for here with no luck. My problem is a whole lot simpler than yours so I hope I find what I'm looking for in the 10,000 posts my search pulled up, none with a title that clearly lead me to what I want to know... How do I set up this Futaba 6EX-2.4GHz system to work with my AX10? It can't be this hard, I'm only using 1 steering servo and 1 ESC on my crawler. The freaking instruction book though is only very specific about plane and helicopter set ups, nothing in this manual is helping me one bit.
If not, if you read all this you'll not only find your answer, but better understand whats being said to store away in your future knowledge data base...
I'm new to all this RC stuff, but not electronics. I ran across your post just looking for any info and tips I could find for the Futaba 6EX, and while your post isn't helping me any, maybe I can help you since it looks like no one is able to answer your question. Or at least help someone else trying to learn this stuff and get a better understanding.
Futaba gave you a great answer, it's this other company that's not doing so well.
I'm going to try to explain this so you understand, which will help you better. Its not that complicated, you just need to be able to picture it in your mind. I don't think I can post pictures here or I'd even draw you up so diagrams.
Lets start where Futaba did in their response to you...
"The signal is a square pulse"
What they are referring to here, or how this term came to name, is how the signal looks when viewed on an Oscilloscope (picture the device your likely more familiar with, the monitor you see in hospital rooms with the up and down line going across the screen, when the line goes "flat", straight across, you know from watching TV this means your dead. Same in electronics when viewed on the O-scope, the frequency of the signal is viewed though instead of your heart beat (the line going up and down.
A square pulse is for the most part considered to be a DC digital signal (though you can chop an AC analog signal to recreate a square pulse by using capacitors and diodes). Its basically an ON or OFF pulse. So if you were to view it on your Oscilloscope you would see the line moving straight up a short distance (power on or DC positive), to the right a short distance (length it moves right is your "pulse width" which Futaba is referring to by "1.0-2.0 mS wide"), the pulse (or voltage for simplicity) goes back to off, the line you see on the scope goes straight down. The voltage is off the same time it is on so your line then travels this same distance still to the right before it repeats the voltage, bringing your line back up, at peak voltage the line then moves to the right again. Looking something like this...
Square Wave Signal:
(The line is starting at 0, off, in the center of your scope)
Code:
__ __ __
__| |__| |__| |__It probably sounds complicated when you read it stated as only...
"The signal is a square pulse of 1.0-2.0 mS wide"
But if you can picture in your mind what this looks like, and know what they mean as explained to you here you will see its actually not that complicated. The "mS" is just the length in time that this signal, in this case, is true on or true off. Its represented by what you view on your scope as the Horizontal lines (the vertical lines remember are on / off).
You could also picture this by you simply flipping a light switch on your wall on and off. You flip the switch on, the line goes up equal to your house voltage where it peaks, the length of time you leave that light on is the distance the line then moves horizontal to the right. When you shut the switch off, the line as viewed on the scope would drop back down to zero. The time you leave it off is the time your dropped line travels further right at zero, before you flip the switch back on and the line goes back up.
Flipping the light switch on your wall off and on at a rate of 1.0 - 2.0 mS would be really fast, you'd likely be closer to 1 - 2 Seconds.
Next, the part that seems to be causing your confusion, is as simple as it sounds...
"that repeats every 20 mS or so"
Maybe you could think of that as a square wave within a square wave. Your sending (transmitting) say a 1.0mS pulse out for 20mS (length of time), then nothing for 20mS, then the 1.0mS pulse is repeated again (this continues as long as you have that switch on the control in the on position).
This is where he is confusing you by talking about servos instead of what your specifically interested in (likely the result of a cut and paste response), which I'm only guessing is not a servo but some type of control circuit...
"The width of the pulse determines the position of the servo"
So he's telling you the length of time that line you see on your O-scope is traveling to the right gets interpreted by the servo so it can determine where center is, and the stops in both directions.
"with 1.5 mS as the nominal center"
The above seemed to slightly confuse whoodie here responding to you when they stated...
"the width of the pulse at full left throw is 1.0 ms. At full right, 2.0 ms. At center, 1.5 ms".
He may have just been simplifying for you but this is inaccurate, remember, the 6EX allows you to adjust your end stops. It's full capability as stated to you by Futaba is 1.0 to 2.0 mS. This would already have you at your limits with no space for adjustment of the stop point. They are actually slightly over extending the time to give you room. It will typically be more like 1.5mS center (90deg), 1.25mS 0deg, 1.75mS 180deg.
So if the controller is repeatedly sending a 1.75mS wave pulse to the servo the servo holds in the 180deg position. The length of time this repeats is so the servo knows when your still telling it what to do and have not gone into off. As long as you are not touching your steering the repeated pulse being transmitted for control is 1.5mS (this is why your wheels will straighten up when you power on, or at least turn to where you have the trim set for the 1.5mS center position).
These wave lengths are pretty much the standard for small servos, that's why Coldnorth is trying to tell you what he has...
"but I don't believe you will ever find a servo that uses anywhere near a 5ms to 20ms pulse width. That implies they are building a product that can't be used with 99.99% of the radios out there, which makes no sense."
I guess they could manufacture a servo to respond how ever the designer wanted it, but when I was shopping for a new steering servo the specs on all of them range at 1.0 to 2.0 mS for positioning, or, aka the standard.
At the heart of everyones confusion here is only seeing that word "width" in there and your leaving the the other word which makes a difference, pulse width and band width in this reference are 2 different terms, just like "red apple" and "red car". They both have the word red, but are 2 different things.
By bandwidth he is referring to the time the cycle repeats, not the length of the pulse width.
"It is suitable for the transmitter which band width is between 5 to 20 ms."
The 6EX has in this reference a "bandwidth" (signal repeat) of 20mS so it will work. The reason 3racing is specifying this is because I noticed when I was shopping for my Transmitter there are some (older FM ones mainly I believe) that only repeat every 50mS which would not work. This 3racing device will be looking for the signal every 5-20mS to hold on or probably think you have turned it off or possibly go into a sleep mode.
The only thing in all of this that actually makes no sense is why this 3racing company would restrict this to only a 5-20mS range when there are control devices in the targeted market that repeat slower than this. You would think they would just make the range open to handle 5-50mS. I know nothing about this product or this company beyond what I read in this very post, but in other devices I'm familiar with this is usually an indication that the control device being used is not specifically manufactured just for this application. Instead its likely either being purchased off the shelf as a universal device, or being borrowed from another more specific device.
With all that said, I need to get back to finding my answer I'm searching for here with no luck. My problem is a whole lot simpler than yours so I hope I find what I'm looking for in the 10,000 posts my search pulled up, none with a title that clearly lead me to what I want to know... How do I set up this Futaba 6EX-2.4GHz system to work with my AX10? It can't be this hard, I'm only using 1 steering servo and 1 ESC on my crawler. The freaking instruction book though is only very specific about plane and helicopter set ups, nothing in this manual is helping me one bit.
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