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Old 01-25-2016, 08:09 AM   #49
knc1
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Posts: 17,212
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Join Date: Feb 2012
Location: Central Texas
Device: No K1, PW2, KV, KOA
Quote:
Originally Posted by uviteru View Post
Thanks so much--the board i was using was this one: http://jim.sh/ftx/

And after some hunting, I found the pinout here: http://jurriaandevos.nl/kindle-4-hac...ial-io-header/

I went ahead and connected the appropriate pins without a voltage reference, and it appears to work! I rebooted the kindle and got the boot messages to show up through putty.

Thanks for clarifying the voltage info!
Translation: The currently recommended board.

Since it is working without the external reference, you must have ordered it for 3v3 (the default) I/O and not changed it after you received it.

You are not the only one that has used 3v3 I/O adapters.

I personally do not recommend that because the manufacturer's hardware reference does not mention 3v3 (or 5v0) tolerance.

But don't panic -

But since the power bus(es) to the SoC's I/O cells can be programed (at run time) to either 1v8 or 3v3, it is reasonable to find them 3v3 (or even 5v0) tolerant.
(It would require additional processing steps (extra expense) to make the I/O tolerance follow the setting of the power bus.)
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