From: Rodolphe Pineau <pineau@rti-zone.org>

Date: August 22, 2011 11:14:29 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Guiding HW Addition

On Mon 8/22/11, at 9:37, Milton Aupperle wrote:

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

Thanks Milton for the precisions.

The Scorpion also has some extra pin that are used as a serial port. As IO0 and IO1 are already used on the scorpion for long exposure, could you have a special version that uses the other 4 pin used as a the serial port (they are in fact also GPIO pins) so that one can keep the long exposure and use the ST4 interface (I do understand that this is not a priority for you and will understand if you chose not to do this).

Rodolphe

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