Min/Max Limits +-250; When and Why?

So, I think on my throttle channel I'm not getting 100% when I'm at 100%.

When would I use +250 and -250 for Min and Max throttle channel?

How does setting the limits effect the Scale?

And the safe value only goes to -150, but if I've set my Min to -250, how does all this work together.

I did read the user manual on these topics, but I guess what I am looking for are practical examples of when to use these values. They are to me, values outside the normal.

thanks

Hi,
May be you should recalibrate your esc ?

I apologize, but I still don't understand.

A practical example for "Min and Max" would be helpful.

Something like:

If I set Min to -10 and Max to 10. I have a range of 20.
If I set Min to -100 and Max to 100. I have a range of 200.
If this was a throttle channel, what would be the difference between the two settings?

Could the "Min and Max" be used to configure a 0 to 100 range.
Example, say I am familiar with a range from 0 to 100.
0 throttle is off.
100 throttle is full.
Is this where I would use "Min and Max", thus throttle off is not -100, but 0.

Sorry, I am sure when you understand it, its obvious.
But when you don't I can dream up all sorts of combinations that are probably wrong because I don't fully understand the function.

The idea posted above isn't correct.

I tried setting Min to 0 and Max to 100 on my mcpx throttle channel.
And tried to set the scale to 100.

Didn't work, ESC needs to see 0 throttle and high throttle to arm and with the above settings the esc never armed, not having read a low signal.

So, how do Min and Max and the -+ Scale things work together?
Are they similar to end point adjustment or something?

Some examples of how they are being used would be great.

Please!!

I have read the documentation:

Min Limit/Max Limit: These values define the minimum and maximum values that the
transmitter will ever send to the receiver (after all scaling, trims and mixer are applied). If a calculated value is outside the min/max range, it will be clipped to either the min or max value as appropriate. Default is -150 for Min Limit and +150 for Max Limit.

Maximum setting is -250 to 0 for Min Limit and 0 to 250 for Max Limit.
Scale-/Scale+: These values define a final scalar to adjust the servo throw. Allowed entries are between 1 and 250. When you alternate Scale+ Scale- will be changed in the same way. If Scale- has been set to a different value than Scale+ both data will act separately until you set them to the same value again.

But it doesn't have any examples, just telling me it is one of the many things determining channel output.

It should be a simple thing to have a throttle start at 0 or 1 and not have to be -100 right?


I want to love this Tx program and I am thrilled it allows so much control, but all the control in the world doesn't help, if only the guy who wrote it understands it.
Deviation for Dummies, would be a nice piece of documentation.

Some transmitters use a 0 to 100 scale for inputs and outputs, others use -100 to 100. Deviation uses -100 to 100. To send the lowest value possible to your ESC so it will arm, set the output to -100 (or less).

An example of min/max use would be to protect your equipment. If the rudder would be damaged by servo throws greater than -80/+90, then set those as min/max so a mistake in the mixer won't break the plane.

Scale could be used to make a 100 value from the mixer correspond to full servo travel on your plane. Then when you're working with the mixers the output will be in direct proportion to servo travel (a 50 out of the mixer will give 50% positive servo movement).

Thanks Hexfet.

So it is just the standard: End Point Adjustment.

How is it determined with an ESC on what values to use?
What if your ESC doesn't have a throttle calibration.

Thanks for the scale example, how does the scale +- differ from the "Scale" in the Mix menu then?

(Trying to wrap my head around it)
Would this be true, if not why:
Min = -200
Max = 200
Scale Min = 50
Scale Max = 50
---- Same As --
Min = -100
Max = 100
Scale Min = 100
Scale Max = 100

No, not the same. Max/min are limits, and scale is a multiplier. In english the code is doing something like "take the output of the mixer, multiply it by the scale, if the result is greater than max limit then set it to max limit, or if the result is less than min limit then set it to min limit." The final result is what goes to the radio.

The scale in the mixers is similar to rate settings in other radios. It only applies for the mix it's part of.

I've not used an esc without calibration. Maybe the documentation states what endpoint values the esc recognizes.

Never understood why all tx use percentages and not true value in u sec, as bit confusing. So 1500 center, 2000full, 1000min.

To simplyfy, could shift the scale, by removing neutral offset. Than scale in micro second would be -500, +500. Equal -100% + 100%?

Thanks Hexfet,

It is making more sense now.

The Mixer page left column is setting up how the radio stick source signals will be delivered to the Mix configurations of each Target. The setup allows you to modify the signal as best possible PRIOR TO mixing for the intended target.

In short, Low, Middle and High range on each stick needs to be set to Low, Middle and High before that value becomes the source for a Mixed Target.

To achieve the best Low, Middle and High setup per channel, the Min, Max, Scale and Sub-Trim values can be used.

Min and Max are the low and high end points.
The feature to add or subtract signal onto each end of the channel is compensating for imperfections in the radio and or the components which cause variance in the pulse width. Ergo A radio value of 100 might not always be 2.0ms. or 2.0ms might not be the full point of the target device. Thus you can fudge the values in min and max to achieve "full".

Scale modifies the channel output but is clipped by Mix and Max levels.
Not quite sure of all its applications.
I would assume the function of Scaling at the source could be utilized to get the best possible throw from each stick (in each specific direction) to maintain a smooth (non-clipped) signal to target device.

Sub-Trim in the Source setup is an -+ offset attempting to adjust the pulse to 1.5ms or a desired off-set to center signal for a given target device.

---

I agree Fernandez, this "So 1500 center, 2000full, 1000min" is a much more tangible concept. It is easier for me to imagine a result of positive numbers, than a percentage of a number less than its negative upper limit.

It might be a cool idea to have a Monitor page that shows the nominal ms values.

because you are trying to calibrate an analog signal compared to a digital one. digital signals are either 1's or 0's, so calibration should seem straightforward, but with an analog signal there is a window of adjustment. They refer to this a "resolution". Calibration is used in all points of communication with a quad. Many in this industry use terminology and obtuse language to confuse people, like in many other industries. Even the way calibration and "resolution" is explained is esoteric and made that way so vendors who can't make a living online can secure a "brick and mortar" service industry. Many old software programs like Librepilot are on the way back and it's only a matter of time

SkyKraken wrote: I agree Fernandez, this "So 1500 center, 2000full, 1000min" is a much more tangible concept. It is easier for me to imagine a result of positive numbers, than a percentage of a number less than its negative upper limit.

It might be a cool idea to have a Monitor page that shows the nominal ms values.

That's not really possible, because those values don't come from us, they come from the Rx. Worse yet, how they're interpreted depends on the servo or ESC they're connected to. So the best we could do is, as you say, a "nominal" value. But you know someone will bitch when the "nominal" value of 1500µs generates 1475µs from their Rx, or the 1500 value they get doesn't result in a half-stick setting on their servo.

The values used internally by the firmware, the percentages it displays, the values communicated to the Rx and the pulse widths generated by the Rx are all different. Deviation displays percentages because that's what most rc people are used to (configurable flight controllers that use ms values are new, and I suspect don't come from the rc community, but the maker community that's used to them) and are easier to work with (it's a easier to figure out half of a 66% signal than of a 1666µs signal).

While I wouldn't object if someone wanted to merge a change that made pulse width display an option in deviationTx (though it probably wouldn't fit on the 7e, meaning most of our user base couldn't use it), I don't think it's worth doing myself. Bit-banging protocols that use pulse width are a holdover from pre-computer days. Newer hardware puts microcontrollers in servos and ESCs, and you can communicate with those with proper serial protocols instead of pulse widths. Once those get standardized, the pulse widths will be what people accuse of being obtuse and intentionally confusing.

i agree, and although the end communication to the motors might be digital, in the communication ecosystem, it isn't absolutely digital. I just got into the hobby 2 yrs ago, not an electronics guy, but question if a pure digital communication from controller to motors is possible with rc?? I hear they're using or working or cell phone bandwidth from what I hear.

In one sense it's impossible because motors are analog devices, so at some stage you need to convert to analog. But a modern ESC has a microcontroller on them, so you could use a digital protocol to talk to it. I don't think as anyone is selling them off the shelf yet, so it would be a project.

isn't DShot all digital? the chip on the esc blehli_s has pwm hardware, but is it not still analog?? thank you

A very quick glance shows at the DShot threads on rcgroups seems to indicate that it's still PWM, which is analog protocol - you get the value by measuring the length of a pulse.

On the other hand, the SimonK ESC software offers an I²C interface, which is digital. That is used commercially by the Afro line of ESCs. Hobby king sells this one , among others.

On the servo side - since they have motors in them - the OpenServo project is an open source hardware/software project for replacement boards for standard size servos that has an I²C interface.

Those take care of the hard part of such a project . What I think of as the hard part, anyway. What's left is a flight controller that will output I²C instead of PWM.

FDR wrote: No, DShot is actually digital:
www.rcgroups.com/forums/showthread.php?2...-ESC-throttle-signal

OneShot and the others are analog ones...

I realise that, but that doesn't make the serial communication cycle absolutely digital. It has pwm hardware right .what else am I missing ? And PLEASE so not spam this forum, especially from that website.