RE: [Paparazzi-devel] Paparazzi joystick control

[mark.griffin]

Hi Safi,
As I understand, the R/C control is used as a "safety link" (see 
http://paparazzi.enac.fr/wiki/Overview).
I guess this is why no one has looked at removing it.
Cheers, Mark

-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Sami Finnilä
Sent: Monday, 20 July 2009 3:09 PM
To: address@hidden
Subject: [Paparazzi-devel] Paparazzi joystick control

Hi,

I recently ran into problems with my traditional 35MHz radio equipment and 
haven't been able to overcome these problems. Then it dawned to me that why not 
use the datalink for manual control as the data modem I have on my A/C is far 
superior in every respect to the 35MHz radio.

I noticed that some code already exists for the joystick control but that the 
code has not been designed to fully replace the traditional radio transmitter 
control. Well, I'm OK with that; I can later on change the code if I wish. 
However, I haven't been able to get even the existing code for joystick control 
to work at any level:

The PPZ Center gives me errors while compiling the existing Joystick code 
(although the airborne code compiles OK): undeclared identifiers joystick_x, 
joystick_y. These are the variables in the settings that are supposed to (?) 
store the joystick's attitude before it's sent to PPZ. 
It's unclear to me where I'm supposed to declare the joystick_x and _y 
variables and, as I'm, also, unfamiliar with Linux drivers and Linux 
programming in general, it's unclear to me how the GCS is supposed to interface 
with the joystick hardware so as to give some reasonable values to these 
variables. Besides, where did the throttle go; it's not in the settings file 
(joystick.xml) although there are references to it in the airborne code. It 
seems to me as if the code is only designed for simulation not flying the real 
deal. I'm OK with that too if only someone could explain me how I can make the 
GCS send the joystick input to the A/C. A nice addition would also be to be 
able to interface with the joystick buttons in order to change the flight mode 
through them.

I (at least) consider myself to be a fairly experienced C/C++ programmer so I'm 
not asking for someone to do it for me but, as it is, the PPZ code is very 
poorly (if not at all) documented so it's very hard to understand what happens 
and where and understanding even little bits of the code is laborious at it's 
best so I'd need some help on a theoretical level: how is it (the joystick 
control) supposed to work and how am I able to interface with a joystick in the 
GCS/Linux in general?

I'm fairly confident that, if someone can help me over the problems with the 
GCS end of the code, I can modify the airborne code to be independent of the 
traditional PPM radio control which would IMO be a step forward in the 
robustness of the PPZ (atleast in my case).

Regards,
Sami Finnilä/Safi
address@hidden



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