APM1 arming failsafe not working?

Archive
1

For some obscure reason new posts are not available in the v2.78 forum so I’m posting this here.

APM1 and v2.78.

If ARMING_REQUIRE is set to 0, 1 or 2 my motor still starts.

I have rebooted the APM1 but throttle is still live!

2

[quote=“Graham Dyer”]If ARMING_REQUIRE is set to 0, 1 or 2 my motor still starts.

I have rebooted the APM1 but throttle is still live![/quote]
The APM1 is unusual in that it has a hardware mux connected to channel 8. When channel 8 is above 1750 the hardware multiplexer passes through the first 4 channels to the servos directly, with no software control. This was done back when the APM software was less reliable, and was meant to give a guaranteed ability to fly the plane manually even if the APM software crashed.
To avoid that mux you need to use a different channel for your flight mode. Try using channel 5 (and in fact this is why copter uses 5 as the default).
If you change FLTMODE_CH to 5 and setup your transmitter so that your mode switch is on channel 5, then you can have channel 8 below 1750 (or just don’t connect it) and you will find that the arming code then works on APM1.
I’ll add a note to the manual for APM1 users.
Cheers, Tridge

3

I’ve fixed that now - thanks for letting me know!
I’m still getting used to the admin controls on these forums.
Cheers, Tridge

4

Thanks Tridge, good to know. Much appreciated!

5

Thanks Tridge, it works great, this a really important feature.

Is it possible to disarm with the rudder stick or is it only with the MP?

6

[quote=“Graham Dyer”]Thanks Tridge, it works great, this a really important feature.

Is it possible to disarm with the rudder stick or is it only with the MP?[/quote]
Hi Graham,
We decided not to allow disarming with rudder as zero throttle with full left rudder is something that pilots do in flight with planes (eg. when going into a spin, or lining up for a cross-wind landing). The risk that you would accidentally disarm is too high.
Cheers, Tridge