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Old Feb 03, 2013, 10:22 PM
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Joined Nov 2012
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R/C - Autopilot Switch

I am building a switch that allows servo control to be switched between a 4 channel R/C and autopilot using a spare R/C channel. It will be used for flight testing the autopilot whilst being able to take control if something goes wrong. I was wondering if this would have any general interest? It uses an Atmel uC to measure the pulse width and a TI video switch to route the signals. The current schema is to have the number of valid control pulses programmable so noise does not make it switch. Drop out of the R/C signal would switch to autopilot. This could be used to hand off control to another transmitter.
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Old Feb 04, 2013, 01:00 AM
Chris Anderson
San Francisco/Bay Area
Joined Mar 2007
939 Posts
Quote:
Originally Posted by magno_grail View Post
I am building a switch that allows servo control to be switched between a 4 channel R/C and autopilot using a spare R/C channel. It will be used for flight testing the autopilot whilst being able to take control if something goes wrong. I was wondering if this would have any general interest? It uses an Atmel uC to measure the pulse width and a TI video switch to route the signals. The current schema is to have the number of valid control pulses programmable so noise does not make it switch. Drop out of the R/C signal would switch to autopilot. This could be used to hand off control to another transmitter.
There are already quite a few products that do this on the market. Here's one, which has been around for years and works well:
http://store.diydrones.com/product_p/br-0001-10.htm
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Old Feb 04, 2013, 10:22 AM
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Joined Nov 2012
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Yes, that is essentially the same. I wonder why they made it so big? If they used a TSSOP package and put parts on both sides of the board they could have shrunk it quite a bit. That is what I did with my video switch:
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Old Feb 05, 2013, 06:01 PM
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Noticed a hardware problem with the diydrone mux. It only allows one control signal for switching the servo signals. At least for my application, the autopilot needs to normally switch the servo signals because the integrators have to be zeroed before switching. In case of an emergency or the ground controller hanging up the R/C system has to be able to regain control.
A software problem is it allows the control to switch whilst a servo signal is active. It should wait until the current signal is finished then wait until the new controller is inactive before allowing the signals through. For that the uC needs to control the gate line of the 74HC157.
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