Startup servo PWM

Id like to put a RC switch on an output channel that starts up above 1600uS, therefore turns on and powers a SIK radio before any Transmitter is connected.
Once the TX is turned on Id like the default output from the TX to turn off the RC switch and kill the SIK radio (This bit I can do.)
Reason - 868 CRSF and SIK 433 not happy together but I want to keep the SIK radio.
I thought about using the Vsw output on the FC board but its already used for VTX power.

Any ideas how to set the startup or default PWM of a channel?

I don’t know about a PWM level but you can set a relay to start high on boot.

Already done that for the Relay_pin that controls the Vsw. There are no more available unless the camera switching is just like a relay. Perhaps it is. I wonder if it can handle a few ma of the sik radio.

You can get a 5v rc switch for $3-4 from most online marketplaces

Yes I have one. They turn ‘on’ usually around 1600us so I want an servo output to boot up above this value (to power the sik radio) for when I am configuring without RC powered or uploading missions. Then before flight I want to turn it off with RC. It would be easy if the switch was ‘on’ with a low pwm and turned off with a high one.

just have the on value as the default then you turn it off with the radio. you can set the trim value on the output channel so its defaults to above 1600.

When set to an RC input channel, the servo output will be zero (not trim value) until it sees RC input from the radio, unless Im missing something. I can set (function) servon to be high but then have no control over that servo channel.

what radio are you using ? you should be able to set that value as part of the failsafe.

These pwm values I need without a radio powered up. I dont want to turn on the TX and flatten the battery while im mission planning. But, I do want to turn off the sik radio before flight via the TX

The failsafe values are held in the receiver.

Its Crossfire. I think you can only set a single failsafe that operates on all channels.

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you could write a basic lua script that does what you want if your running a h7 chip.

Yes its H7. I was hoping to avoid writing a lua as Im extremely rusty with that stuff. (and my wife already thinks I spend too much time on this)

I think we have seen other similar requests and the answer was at the bootloader level. But I may be confusing this with something else.

I like the idea of turning off my WiFi radio on arming though.

another option would be a RC relay rather than a switch then you can just connect to NC output for the behaviour you want.

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Yes Dave, Ive seen requests from a few years back on older versions that didnt seem to find a solution. I was hoping things had moved on.

There are many servo output functions. Ive been going through them to see if they could be adapted, like landing gear or winch but none are simple. Gripper is an option but I already have one on the copter.

I think this is the most logical solution.

I already have 2 of the solid state types so brainstorming to think of a solution using those. Yep I guess I need to add to basket.

It would be good to have a servo.x option armed pwm, disarmed pwm.