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[Solved] was: Need electrical circuit help (Rotating Monitor w. Parallel Port)
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csa3d:

--- Quote from: DaOld Man on January 24, 2009, 03:23:15 am ---see if another pin is also going high on boot up. If it is, place the highlighted part of your circuit back in, and tie the base resistor of Q3 to the that third output.
Thats one way.

--- End quote ---

Well, that chart at the top says that pins 2-9 all go high during bootup.  I guess I'll give that a try next.  Output pins 2, 3, and 4 are currently in use... would you suggest any of the remaining pins as having a better chance of working over the others?  I'm currently considering pin 9, because it's the last of the outputs which goes high after boot.  Not sure if they do this low to high swap in any particular order to be honest.

-csa
MonMotha:
Try tying all of 12, 13, and 15 to parallel port ground.  This *should* tell Windows that the device is not IEEE1284 compliant and that therefore it can't be a PnP device.  This should make it never touch the strobe line (pin 1) as it has to assume that there may be an old printer hooked up, and such an action could cause it to start printing things.

Once you accomplish that, you can use pin 1 as an enable.  Remove that switch/relay/whatever and install Q3 with its emiter tied to the base resistors of both Q1 and Q2.  Once your OS is up, your control software can set bit 0 of the control port low to "enable" everything, then use all 8 data lines as you please.
csa3d:

--- Quote from: MonMotha on January 24, 2009, 09:41:11 am ---Try tying all of 12, 13, and 15 to parallel port ground.  This *should* tell Windows that the device is not IEEE1284 compliant and that therefore it can't be a PnP device.  This should make it never touch the strobe line (pin 1) as it has to assume that there may be an old printer hooked up, and such an action could cause it to start printing things.

--- End quote ---

Interesting..

Let me ask you then, if I tie 12, 13, and 15 to ground... and i'm using pins 12 and 13 in that circuit which controls the sensing of when a limit is reached, I would just have to substitute two other input pins instead.. say 10 and 11 instead then?  I know this is easily done given the current software and setup.


--- Quote from: MonMotha on January 24, 2009, 09:41:11 am ---Once you accomplish that, you can use pin 1 as an enable.  Remove that switch/relay/whatever and install Q3 with its emiter tied to the base resistors of both Q1 and Q2.  Once your OS is up, your control software can set bit 0 of the control port low to "enable" everything, then use all 8 data lines as you please.

--- End quote ---

Not sure if the software is ready for this design change yet.  DaOldMan, what do you think about this suggestion?  (After all, he's the one writing the software I'm using here :) )

Thanks for the suggestion!
-csa


csa3d:
What are the blue top mount screw thingers called on this image



and can one purchase them from RadioShack or are they special order elsewhere?

-csa
Level42:
Terminals I guess.

I'd go for a simple solution like a delay like Cametron suggests. A 555 would be ideal for this.

On the other side, can't you configure the parallel port in the bios to set it as a old-fashioned bi-directional port and would that change the behavior on start-up ?
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