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Initial state of GPIO?

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I have recently discovered that the initial state of the GPIO is always '1' = asserted. This won't work in my application, I want them to be '0'= de-asserted then I power up the device. Does anyone have any ideas?

Regards Jonas - Sweden
asked May 19, 2005 in Plug N' Play by jofi New to the Community (3 points)
recategorized Dec 18, 2013 by tuxembb

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3 Answers

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Are you working with our Integration of Development kit?

With our Integration kit such a change would entail modifications to our boot loader, post and the application. Would it be feasible for you to place invertor buffers between the GPIO and your connected device(s)?

Using the Development kit this should be possible, however, you would be required to develop your own embedded application.

answered May 19, 2005 by Cameron Seasoned Professional (221 points)
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Cameron, are you among the Digi staff?

I'm using the Integration kit.

The problem is that I have already ordered and received the circuit boards. I took it for granted that you could change the initial state. But now I know that it's not possible. Would it be hard for you to implement that the value set in SYSTEM/GPIO is stored and used the next time the device is powered up?

Regards Jonas
answered May 19, 2005 by jofi New to the Community (3 points)
0 votes
All devices should power up in the high impedance state. That way, you won't damage anything attached to the GPIO lines. I don't know any micros that will power up in the low state...

You will have to modify the direction (maybe?) and output values very early on...possibly in netosStartup().

answered May 26, 2005 by Timmyb New to the Community (22 points)