Quick Question: Servos

[InvaderZim]

Hi all,

Can an 18x (or any picaxe for that matter) support more than 1 servo at a time? Can all 8 outputs be servos if I choose?

And just curious: do all 8 pulses happen at the same time? Or one after another? That probably doesn't matter for my purposes, just got to thinking.

Thanks!

 

[Technical]

yes, pulses are one after another, not at the same time. But that doesn't matter for servos anyway, they just expect a pulse every 20ms or so.

 

[InvaderZim]

Excellent, thanks!

 

[LFLekx]

Might I add a question...

Going over the manual, it says that servo commands are reset when a high or low command is executed - is this restricted to the pin that the high or low is altering?

Say, for instance, I have a servo pulse-train running on pin 3 of an 18X, and I then set pin 4 high. Does that kill the pulse-train on pin 3?

 

[BeanieBots]

High/low will only effect the servo pulses if it is on the same pin.

 

[Wrenow]

yes, pulses are one after another, not at the same time. But that doesn't matter for servos anyway, they just expect a pulse every 20ms or so.

Hmmmm. This may provide a solution for a problem I had been pondering and simplify a one of code - IF I am understanding correctly.

So, the servo pulses are output sequentially, say output 1 then output 2 then output 3 etc. Could you multiplex these pins together on a single output buss to get a single output pulse stream similar to a regular Radio Control stream? Would you need diodes at each output before the buss?

Cheers,

Wreno

 

[BeanieBots]

That should work,(similar to the Tx stream). Just diode OR them onto a single line with a pull down.
Never checked the exact timing. Might not be much gap between say "1" going low and "2" going high. Then decode with a series of pulsin's.
Could also be a solution to albrand's problem!

 

[LFLekx]

High/low will only effect the servo pulses if it is on the same pin.

In that case... the simulator is messed up. Because when I start a pulse train on one pin, then set a different pin high, the first pin indicates a high as well.

(I don't have an oscilloscope to check...)

 

[Wrenow]

Could work for Albrand, but I think the offset add solution I offered is a better fit in his situation and easier to code/decode, since it is one proportional and one digital channel he is trying to mix/multiplex, and you can get that information into a single pulse.

Cheers,

Wreno