Re: [Paparazzi-devel] Cannon Launch Detection

[David Bryant]

Thanks Pascal,

That's extremely helpful. I've got a module running, following the 
outline that you provided. I'm reading from the ADCs and want to be sure 
I understand how they work correctly.

From what I can tell, you declare a buffer (struct adc_buf) and 
register it for samples to be accumulated in it (adc_buf_channel). Then 
in each update it would seem you can either:

* Use the average value accumulated: buf.sum / buf.av_nb_sample

* Or look at the samples directly buf.values[0..buf.av_nb_sample - 1]

Is this correct?

What causes this structure to get reset?

What is the member buf.head about?

Obviously I'm having a guess about all this. Am I on the right track?

I will endeavor to contribute to the wiki and submit anything useful 
that I create back to the project.

Are modules automatically written for paparazzi automatically licensed 
under GPL?

Thanks,
Dave

Pascal Brisset wrote:
> Hi David,
>
> the modules mechanism should (almost) provide the features you 
> require. You will have to write:
> - a module description, a file in conf/modules/ : In your case, it 
> will contain only a call to your init function, a call to your 
> periodic task and the declaration of .c and .h files:
>
> <!DOCTYPE module SYSTEM "module.dtd">
> <module name="cld">
>  <header>
>    <file name="cld.h"/>
>  </header>
>  <init fun="cld_init()"/>
>  <periodic fun="cld_check()" period="1./60" autorun="TRUE"/>
>  <makefile>
>    <file name="cld.c"/>
>    <flag name="ADC_CLD" "ADC_7"/>
>  </makefile>
> </module>
>
> - your .c and .h files in the sw/airborne/modules/cld/ folder:
>
> ---8<--- .h ---------
> ...
> #include "std.h"
> bool cld_launch_detected;
> ...
>
> ---8<--- .c ---------
> #include "cld.h"
> void cld_init(void) {
>  ... initialisation code for your adc ...
>  cld_launch_detected = false;
> }
> void cld_check(void) {
>  if (... check condition...) {
>     cld_launch_detected = false;
>     cld_cld_status = MODULES_STOP; // stop calling me
> }
>
>
> - your flight plan, for example using an exception in the Holding 
> Point block (in basic.xml):
>
>    <block name="Holding point">
>      <exception cond="cld_launch_detected"  deroute="Takeoff"/>
>     ...
>    </block>
>
> - and finally in your airframe file:
>
>  <modules>
>    <load name="cld.xml"/>
>  </modules>
> ...
> # in the makefile section:
>   ap.CFLAGS += -DUSE_MODULES
>
>
> In the current implementation, 60Hz is the maximum frequency for a 
> periodic task in a module. If you really need more ... let us know :-)
>
> Hope this is enough
>
> And feel free to update the wiki :-)
>
> --Pascal