Re: [Paparazzi-devel] Re: Electrical connections with the Tiny and PPM Encoder Board

[Chris Gough]

Hi Ana,

> When you use the PPM encoder board, do you still connect your
> servos to the autopilot?

yes, that's how I do it.

rx ==(PWM)==> encoder --(PPM)--> autopilot ==(PWM)==> servos/ESC

> Because if the servos are connected to the
> autopilot, there is no way of independent powering, is it?

I don't know, it's an interesting question. I've never done it but am
convinced it's a good idea.

I did wonder about using "optical isolators" in the past, but haven't
needed to. e.g:

http://www.sparkfun.com/commerce/product_info.php?products_id=9118

In the absence of voltage/noise issues, there is probably a better
way. Would it be dangerous make a wiring loom that commingles a 5v BEC
to common (-) with SRVx_GND, use BEC (+) instead of SRVx_+5v (and keep
the SRV_x, obviously)?

That would be similar to cutting (+) on my ESC (with BEC) and
inserting a BEC on an unused channel. I think that's a normal practice
in standard RC land, I probably do it more often than I use the ESC's
built in BEC (because most of the BECs built into in my ESCs are
crumby ones that can't supply a useful current when used with a 4S
LiPo).

Chris Gough


On Wed, Jul 14, 2010 at 4:49 PM, Ana García <address@hidden> wrote:
> Hi Chris,
> thank you for your explanation...I still have a question. When you use the
> PPM encoder board, do you still connect your servos to the autopilot?(that's
> what I guess...because I can imagine servo extensions from receiver to ppm
> encoder board...unless you mean Y servo extensions from receiver to ppm
> encoder board and servo...). Because if the servos are connected to the
> autopilot, there is no way of independent powering, is it?
>
> As I don't have a PPM encoder board yet(and it is not available on PPZUAV by
> now), I think I'll try the "receiver-classix configuration", getting the PPM
> signal out and then back in the receiver(this way I'll have the servos and
> receiver powered from the motor BEC), hope this works with tiny2.11. I will
> get my corona RP8D1 receiver on Thursday. If I crash it, I'll wait for a PPM
> encoder board, which I think is a great solution.
>
> Thanks for your patience, I'm not used to work with this things, and
> everything is like a challenge.
>
>
>
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