From: "John" <jbuckley1@mac.com>

Date: August 21, 2011 8:48:44 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: Guiding HW Addition

Hi Milton, 

I was looking at the V2 interface jpg and I had a question as to the 3904 transistor. Should the part list it as NPN instead of PNP?

Clear and steady skies,

John B.

--- In Astro_IIDC@yahoogroups.com, "milton_aupperle" <milton@...> wrote:

Hi Folks;

Second time is the charm and here is the revised PCB that should work.

http://groups.yahoo.com/group/Astro_IIDC/files/Other/GPIOtoST4_Interface_V2.jpg

I'll be running tests tonight after it cools down and the sun isn't baking the patio.

One thing I found out is that the latency time is immensely faster with GPIO FireWire versus the GPUSB. The GPUSB takes 8 milliseconds (8/ 1,000th of a second) to send a pulse to open or close a switch.

With Firewire and the GPIO control, that drops to 0.08 milliseconds (8/ 100,000th of a second) to send a pulse to open or close a switch.

Astro IIDC measures the round trip time to send a pulse and if a correction would take less time that this latency, then we would not make the correction until it would be greater than this. This will improve corrections response time.

TTYL..

Milton Aupperle