Tips 'n' tricks using KK2.0 v1.6++ firmware by RC911


Accurate RX input adjustments
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The KK2 tuning guides tell you to use sub-trim on your transmitter to make center position show as zero on the KK2 Receiver Test screen. What they don't tell you is that the displayed value is quite inaccurate (zero can mean anything from 0 to 1%) and that can be enough to make your model drift off. I therefore recommend that you keep adjusting the sub-trims until you see the text "Center" displayed behind the channel value on the Receiver Test screen (or until the value keeps changing between 0 and -1).
The lower throttle endpoint should be adjusted until you see the text "Idle" displayed. Arming will otherwise be refused.


RX input pin gone bad
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If one of the KK2 RX inputs has stopped working you can use the Channel Mapping feature to assign the AUX input pin to the defective channel. If, for example, your KK2's rudder input has gone bad you can change the channel mapping from 1, 2, 3, 4, 5, 6, 7, 8 (default) to 1, 2, 3, 5, 4, 6, 7, 8. The KK2 AUX input connector pin will then be working as rudder input so this is where you plug in your rudder RX cable now.
You can of course no longer control flight modes (nor the lost model alarm) from the AUX switch, but you can lock it in one position (e.g. SL Mix) by using the KK2 AUX Switch Setup feature. I recommend setting all five AUX functions to the same value.


Using virtual channels
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If you want to control features assigned to AUX2, AUX3 or AUX4 you can do so, but you'll have to sacrifice your AUX input to control the other (virtual) channel.
To control gimbal pitch offset (AUX2) from your AUX input channel you would change the channel mapping from 1, 2, 3, 4, 5, 6, 7, 8 (default) to 1, 2, 3, 4, 6, 5, 7, 8. By doing so you can no longer control flight modes (nor the lost model alarm) from your AUX switch, but you can lock it in one position (e.g. Normal SL) by using the KK2 AUX Switch Setup feature. I recommend setting all five AUX switch functions to the same value.


Crash investigation
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Watching your model fall out of the sky for no obvious reason can be very frustrating, but the KK2 LCD can give you a few valuable hints about what went wrong (so don't be in a hurry to disconnect the battery, unless you absolutely have to). I recommend taking pictures of your crashed model (including the LCD) so that you can study them later.

1. Status text: If the status text on the SAFE screen reads "RX signal was lost!" this means the radio signal reception was interrupted. Avoid flying out of range or in noisy (e.g. WiFi) areas.

2. Battery voltages: If the logged battery voltage on the SAFE screen is very low this could mean that one or more ESCs shut down due to low battery voltage or intermittent connection. This won't work unless the the flight battery is connected to the KK2 battery monitor connector (BEWARE! Pay attention to the pin arrangement and battery polarity!). Also remember to set your Low Voltage Alarm.

3. Flight timer: If the timer value in the upper left corner of the SAFE screen reads zero (i.e. 00:00) when you arrive at the crash site then this means that the board was reset due to an intermittent power failure or brown-out, so check your wiring, connectors and BEC/ESCs. Avoid powering servos from the 5V supply used by the KK2 controller (M1 or the receiver side).
