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Min_Check in Betaflight
#1
Do you guys usually fiddle with min_check? I found my new (used taranis) was not giving any model throttle until it went above about 1150uS. 

Basically the receiver tab saw the signal change, but the motors didn't spin any faster til it went above 1150uS. I changed the min check on my models to 1030 which seemed to have fixed the problem. But it bears the question of why I needed to change this? 

I had 0 dead zone with my other taranis, and min_check 1100 has been standard for awhile. My old procedure was fine the correct idle speed, calibrate motors (multishot) then set the trim on my throttle til about 15uS below that min throttle. This resulted in almost no dead zone.
#2
I set min_check to 1005 on all my quads. The only reason this isn't default is Boris got tired of explaining to people with shitty radios why they couldn't arm. Some low quality or incorrectly set up radios couldn't get below 1100us and people couldn't arm, hence the default setting.
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#3
Min_check is how much throttle stick input before the FC sends the min_throttle signal. Cche is right that you have to be below min_check to arm. Min_check of 1100 is just deadband. Too low of a min_check can be dangerous if you have a lot of radio jitters. Can cause your quad to take off after you arm.
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#4
(11-Oct-2017, 02:38 AM)voodoo614 Wrote: Min_check is how much throttle stick input before the FC sends the min_throttle signal. Cche is right that you have to be below min_check to arm. Min_check of 1100 is just deadband. Too low of a min_check can be dangerous if you have a lot of radio jitters. Can cause your quad to take off after you arm.

That's not right.

min_throttle is what the flight controller sends to the ESC when you are armed unless MOTOR_STOP is enabled.

It is correct to say that setting min_check too high will result in a deadband at the lower end of the throttle though as the flight controller will only increase throttle from min_throttle to the current throttle setting when the throttle passes the min_check value.


I don't see how setting min_check too low would "cause your quad to take off after you arm".

Maybe I've missed something in your explanation?
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#5
I think we are saying the same thing. Min_throttle is the minimum PWM value that the FC sent to the motors. But it doesn't get send until the stick deflection go pass min_check.

It would be rare for the quad to take off, but it could happen. Example, you set your min_check to 1005. Say your radio jitter is 1000-1020. When you arm, the radio is 1000. All of a sudden the jitter goes to 1020, motors will spin up as if you engaging the throttle. If jitter is even higher, motors will spin up even more. Maybe not enough for quad to take off, but it could.
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#6
If you have disarmed your quad or using MOTOR_STOP and you arm then the value of min_command is send to the ESC, this value must be low enough soo the motors don't start to twitch or something.

If you arm your quad without MOTOR_STOP then the value of min_throttle is send to the ESC, this is te minimum value where the motors spinning smooth.

min_check is just the value for your throttle stick to check if it's low enough to arm, in this condition the value of min_command is send to the ESC if you are not armed yet.
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