From: Milton Aupperle <milton@outcastsoft.com>

Date: August 22, 2011 10:37:40 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: Guiding HW Addition

Hi Rodolphe;

Yes that is correct. As long as the physical GPIO pins map to logical IO 0, 1, 2 and 3 then AstroIIDC can control the ST4 port.

Note that the Version 3 schematic does not need power (3.3 volts) and you should only be using the V3 schematic. You only need the 4 GPIO lines and a ground.

My initial layout assumed that I needed to provide signalling power to the ST4 pins, which is what the 3.3 volts power line was needed for.

As it turns out,  that is wrong and the ST4 provides it's own power to the pins and the transistor just acts as a switch.

PS: I have to check my notes for the Dragon Fly cameras, as I am not sure if those cameras work. They used a different internal method for working with the pins.

HTH..

Milton Aupperle

On 2011-08-22, at 10:25 AM, Rodolphe Pineau wrote:

On Mon 8/22/11, at 8:00, milton_aupperle wrote:

Hi John;

Your right, it should have been NPN. I have corrected it in the final schematic layout here:

http://groups.yahoo.com/group/Astro_IIDC/files/Other/GPIOtoST4_InterfaceV3.jpg 

Note that you also need to connect the Cameras ground (Pin 5) to the ST4 ground (Pin 2) or the GPIO pins won't "trigger" properly, which has been added to the Version 3 layout.

I also included an image showing the final product (in a plastic enclosure box) mounted on the scope.

I still have testing to do, but so far it shaping up to work really well.

Thanks..

Milton Aupperle

Hi Milton,

Your interface description shows an 8 pins connector for the camera but the scorpion has a 12 pins connector. I assume it's just a matter of mapping the correct ping (IO0 to IO3, GND and +3.3v ).

Rodolphe

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