Re: [Paparazzi-devel] 5v pulse required for CHDK on Lisa/M2

[Hector Garcia de Marina]

Agree with the last solution of Christophe. It would be desirable using an optocoupler for keeping cleaner the GND for the analog signals especially.

On Fri, Nov 2, 2012 at 9:07 AM, Christophe De Wagter <address@hidden> wrote:

Use e.g. a 2k to 20k Ohm resistor connected from USB+ to 5Vusb to pull it up. Use any N-MOSFET transistor (e.g. bss138) with its Gate to any paparazzi IO pin, its Source at Ground and it's drain at the USB+ pin, pulling it to zero when the io pin in paparazzi is higher than 0.7 volt.

If you have no Fet but have a bipolar NPN transistor around (like a bc547) then you just need 1 extra resistor of about 10x more ohm in between the paparazzi board and the NPN.

Another solution we use most of the time is a bipolar optocoupler switch instead of a MOSFET. Then there are no copper connections between the noisy camera ground and the autopilot/GPS/modem ground for optimal telemetry and gps signals.

On Nov 2, 2012 12:27 AM, "Marc Schwarzbach" <address@hidden> wrote:

Hi Gerard,

since there is only very low current involved (measured) I connected the USB + line to 5V and the - line to an IO, using it as drain... Did this on a LPC based board. Not sure if I used a resistor, did that some time ago and now it´s deep inside the plane.

It has been working many flights triggering my CHDK camera now.
Probably not a "correct" solution and not sure if it works with the STM in the LISA.

Of course, I also had to reverse the logic in the dc_cam code...

If you find a solution, please post, anyway!

Cheers

Marc


-------- Original-Nachricht --------
> Datum: Thu, 1 Nov 2012 19:22:40 -0300
> Von: Gerard Toonstra <address@hidden>
> An: address@hidden
> Betreff: [Paparazzi-devel] 5v pulse required for CHDK on Lisa/M2

> Hi all,
>
> I think I'm nearing the point where I can start some test flights with my
> setup.
>
> I'd like to use a camera to take pictures. In my case that's a Canon with
> CHDK extensions.
> When the software detects 5V at the USB port, it triggers a picture to be
> taken.
>
> I'm connecting this to one of the ADC's, but the voltage is 3.3v and not
> enough to trigger
> the camera. I've verified this using a 3.3v supply from an arduino. So I
> definitely need a higher
> voltage.
>
> Is there any other pin I could use that does output 5v, which is
> configurable in the dc_cam module,
> or can this only be solved by inserting a level shifter?   If a level
> shifter is required, what
> are recommended components / boards?
>
> Regards,
>
> Gerard

_______________________________________________
Paparazzi-devel mailing list
address@hidden
https://lists.nongnu.org/mailman/listinfo/paparazzi-devel

_______________________________________________
Paparazzi-devel mailing list
address@hidden
https://lists.nongnu.org/mailman/listinfo/paparazzi-devel

--
Héctor