Re: [Paparazzi-devel] Joystick question

[Gautier Hattenberger]

Hi,

I think that sending the RC_3CH with the XBee api mode takes probably 
more bandwidth than sending the RC_4CH with transparent mode. For now, 
it is not possible to use the RC_3CH with input2ivy as it doesn't have 
an ac_id field that is mandatory with it.
As Martin said, it is much better to send the mode each time. When you 
have a joystick and that you want to use buttons to set the mode, it is 
possible by declaring a "variable". Look in the file 
attack3_booz_nav.xml for an example.
I will probably make a proper DTD file and a wiki page some day to 
explain how it works...

Gautier

On 08/05/2011 08:25, Martin Mueller wrote:
> Hi Chris,
>
> the original idea for joystick was to have a very short transmission 
> time. It turned out that the first implemented RC_3CH message takes 
> 1ms to transmit as XBee broadcast message (measured with a HF meter). 
> Most of that time is guard time, addressing and checksums. An 
> additional byte only takes some tens of microseconds to transmit.
>
> The mode information is vital to the message. If mode change 
> information is lost and the aircraft interprets auto1 controls as 
> manual controls you could have an issue.
>
> For RC_3CH the mode was encoded into the throttle byte. As long as you 
> do not want to do 3D hovering UAVs should be fine with a 6-bit only 
> throttle resolution.
>
> Martin
>
> On 08.05.2011 07:44, Chris wrote:
> > Hi.
> > I finally made everything work well with my Saitek Aviator and i also
> > made some changes
> > that aim in reducing modem bandwidth so i need to ask for your opinion
> > on those.
> >
> > 1) added a variable to the rc_datalink.h and .c files
> > ("datalink_pprz_mode") that controls the autopilot's mode:
> >
> > extern volatile int8_t datalink_pprz_mode;
> >
> > #define NormalizeRcDl(_in, _out) { \
> > _out[RADIO_ROLL] = (MAX_PPRZ/128) * _in[RADIO_ROLL]; \
> > Bound(_out[RADIO_ROLL], MIN_PPRZ, MAX_PPRZ); \
> > _out[RADIO_PITCH] = (MAX_PPRZ/128) * _in[RADIO_PITCH]; \
> > Bound(_out[RADIO_PITCH], MIN_PPRZ, MAX_PPRZ); \
> > _out[RADIO_YAW] = (MAX_PPRZ/128) * _in[RADIO_YAW]; \
> > Bound(_out[RADIO_YAW], MIN_PPRZ, MAX_PPRZ); \
> > _out[RADIO_THROTTLE] = ((MAX_PPRZ/255)*(127+ _in[RADIO_THROTTLE])); \
> > Bound(_out[RADIO_THROTTLE], 0, MAX_PPRZ); \
> > _out[RADIO_MODE] = MAX_PPRZ * (datalink_pprz_mode - 1); \
> > Bound(_out[RADIO_MODE], MIN_PPRZ, MAX_PPRZ); \
> > }
> >
> > 2) The variable was added to the settings.xml file and the joystick .xml
> > file was configured to change the variable like this:
> >
> > <message class="ground" name="DL_SETTING" on_event="stick_right_button">
> > <field name="index" value="IndexOfSetting(datalink_pprz_mode)"/>
> > <field name="value" value="2"/>
> > </message>
> >
> > <message class="ground" name="DL_SETTING" 
> > on_event="stick_center_button">
> > <field name="index" value="IndexOfSetting(datalink_pprz_mode)"/>
> > <field name="value" value="1"/>
> > </message>
> >
> > <message class="ground" name="DL_SETTING" on_event="stick_left_button">
> > <field name="index" value="IndexOfSetting(datalink_pprz_mode)"/>
> > <field name="value" value="0"/>
> > </message>
> >
> > That way i don't need the "MODE" portion of the RC_4CH message so the
> > message length is now reduced by one byte and since that particular
> > message is repeated at a high rate this should reduce bandwidth usage,
> > am i correct or i dont gain anything by doing that?
> >
> > Chris
> >
> >
> > _______________________________________________
> > Paparazzi-devel mailing list
> > address@hidden
> > https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>
>
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