LibrePilot Forum
General Category => General Discussion => Topic started by: Tomcatt on June 12, 2016, 05:03:39 am
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Is anyone here using MultiShot? My ESC's takes a bit longer to finish booting up or stop playing all it's tunes. I wonder if it's something to do with the time signals going to them.
In RaceFlight there's some loop_ctrl that goes to them and if I slow it down the ESC's takes some time to boot. Does LibrePilot have the same options here?
Thanks.
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I have no idea for sure. I think I read it some where. And I may be completely wrong. But I believe LP and say a CC3D running sbus(or some other serial reciever) also using oneshot or multi shot, the fastest the FC and Gyro Sync can be is 1khz/1khz. And if I understand oneshot and multi shot correctly. It's a a speed thing of course(faster update rate) but it's more about the resolution of the esc. So multi shot has more steps from min to full throttle(more resolution) for better control.
That's the way I understand it currently. I hope somebody who knows will comment and set me stright.
As far as multi shot itself. I'm still currently using blheli 14.4. On littlebees. I've found it flys great and I don't really have a reason to change it. So it's still "oneshot" for me.
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I have no idea for sure. I think I read it some where. And I may be completely wrong. But I believe LP and say a CC3D running sbus(or some other serial reciever) also using oneshot or multi shot, the fastest the FC and Gyro Sync can be is 1khz/1khz. And if I understand oneshot and multi shot correctly. It's a a speed thing of course(faster update rate) but it's more about the resolution of the esc. So multi shot has more steps from min to full throttle(more resolution) for better control.
That's the way I understand it currently. I hope somebody who knows will comment and set me stright.
As far as multi shot itself. I'm still currently using blheli 14.4. On littlebees. I've found it flys great and I don't really have a reason to change it. So it's still "oneshot" for me.
Hi NicholasDavid.
The use of shortened pulse pwm protocols is to provide a faster data transfer. It is not just a matter of refresh rate. OneShot125 transfers the data in a time comprised between 125 and 250 µS, while the PWM takes from 1000 to 2000 µS. This is the real advantage.
Regarding the resolution, it is exactly the opposite. The shorter the pulse, and the lower the resolution. So multishot have the worst possible resolution.
It is my personal opinion that the bulk of the improvement you have with oneshot125 when compared to the classic 1000/2000 PWM.
In LibrePilot I don't get any improvement using OneShot42 compared to OneShot125. OPTune give the same PIDs. For example OPTune allows a significant increase in PIDs going from PWM to OneShot125.
To cite another example, at the present time OneShot42 is giving some desync problems to KISS fc users. Flyduino advised to return to OneShot125 if problems occur, even considering the fact that their tests don't realize any apparent increase in performance between OS42 and OS125.
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Well there you go. Thanks for the explanation.
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I have no idea for sure. I think I read it some where. And I may be completely wrong. But I believe LP and say a CC3D running sbus(or some other serial reciever) also using oneshot or multi shot, the fastest the FC and Gyro Sync can be is 1khz/1khz. And if I understand oneshot and multi shot correctly. It's a a speed thing of course(faster update rate) but it's more about the resolution of the esc. So multi shot has more steps from min to full throttle(more resolution) for better control.
That's the way I understand it currently. I hope somebody who knows will comment and set me stright.
As far as multi shot itself. I'm still currently using blheli 14.4. On littlebees. I've found it flys great and I don't really have a reason to change it. So it's still "oneshot" for me.
1kHz? In RaceFlight with a REVO I can get it up to 32kHz running M8 but that's with the 14.6 modded version.
Hey, what about passthrough? Do you think LP will have that feature for the ESC's?
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1kHz? In RaceFlight with a REVO I can get it up to 32kHz running M8 but that's with the 14.6 modded version.
Hey, what about passthrough? Do you think LP will have that feature for the ESC's?
According to datasheet MPU6000 (Revo) and MPU9250: "sample rate is programmable from 8,000 samples per second, down to 3.9 samples per second".
So you can get at most 8kHz RAW gyro, that does not even account for filtering.
What would be the measurable flight benefit of running control anything above 8kHz besides eating CPU cycles ?
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M8 was the 8k/8k/32k
My bad, I forgot all about how the option M8 is. I guess setting it too high would be a bad thing. This is why I like asking you guys questions. Thanks
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