OpenTX - Application Note 06
Weights and Expo Selected By a 3 Position Switch
Set up a three position switch to set weights and exponential curves for three different flying styles. The weight/curve combinations are called Low, Medium and High to describe the aircraft performance types.
Add audio files to announce the names when they are selected.
Switch SG is used as the selection switch.
Low performance type has aileron, elevator and rudder servo travel limited to +/- 60% with a 40% exponential curve.
Medium performance type has aileron, elevator and rudder servo travel limited to +/- 80% with a 20% exponential curve.
High performance type has full 100% servo travel with a 0% exponential curve.
All modes have 100% throttle range.
The weight and expo combinations are set up in the inputs screen.
Inputs Set Up
The throttle is not altered by this feature. It remains as follows.
Two lines are added to each of the default lines of the aileron, elevator and rudder channels, The Multiplex function of the added lines is ‘replace’. The completed lines are as follows.
Switch SG controls all three channels
The lines which have their weights in bold numbers are the active lines. In the example above, the single throttle channel is active always, and the ‘Low’ lines are active indicating that switch SG is up. With switch SG in the mid position, the ‘Med’ lines are active. With switch SG in the down position, the ‘High’ lines are active.
Audio File Set Up
We need audio files that say ‘Rates Low’, ‘Rates Medium’ and ‘Rates High’.
There are no standard audio tracks on the SD card that say these phrases so you have to create them, transfer them from your PC to the SD card and then use a special function to play them.
Create the Audio Tracks.
The audio tracks can be created using a PC that has a microphone and recording / editing software like NCH Wavepad. The audio file must be a wav type file, mono 32000Hz. Make one track that says ‘Rates Low’ called ‘rateslow.wav’, one track that says ‘Rates Medium’ called ‘ratesmed.wav’ and one track that says ‘Rates High’ called ‘rateshi.wav’.
Transfer the Audio Tracks to the SD Card
With the radio power off, remove the SD card from the battery compartment of the radio and plug it into the PC. Transfer the wav files to the SD card folder SOUNDS / en. Reinstall the SD card in the radio.
Create Special Functions That Play The Audio Tracks
Create the following special function lines. In this example, SF2, SF3 and SF4 are used.
Confirm It Works
Display the channel monitor screen.
When switch SG is up, the ranges of ail, ele and rud channels are from to –60% to +60% when the sticks are moved to their full ranges.
When switch SG is in the centre, the ranges of ail, ele and rud channels are from to –80% to +80% when the sticks are moved to their full ranges.
When switch SG is down, the ranges of ail, ele and rud channels are from to –100% to +100% when the sticks are moved to their full ranges.
When switch SG is moved to the up position, ‘Rates Low’ is announced.
When switch SG is moved to the mid position, ‘Rates Medium’ is announced.
When switch SG is moved to the down position, ‘Rates High’ is announced.
The weights and expo settings for each channel can be changed separately for each channel. They can be ‘tuned’ to suit each of the performance types.