SAM L21 Xplained Pro - VDDIO

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Bronze Markawneil
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Posted by awneil: Sat. Jun 13, 2015 - 06:13 PM
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Anyone here know anything about the SAM L21 Xplained Pro; in particular, running at a different VDDIO ?

 

I have a question posted in The Other Place: http://www.at91.com/discussions/...

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Tools, Evaluation and Development Kits (AVR-related)
Last Edited: Sat. Jun 13, 2015 - 06:15 PM
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alexru
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Posted by alexru: Sun. Jun 14, 2015 - 03:52 AM
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For EDBG inputs it is not a problem, since your VDDIO will be less than VDD of the EDBG.

 

EDBG will never have any outputs configured if you don't access corresponding function. And the only thing you really need form EDBG is SWD, which is powered from VDDIN. So just don't open a virtual COM port, since realistically there is no way to access SPI or TWI connection anyway.

 

PS: I'm not going to that site, I think ARM questions belong here.

 

NOTE: I no longer actively read this forum. Please ask your question on www.eevblog.com/forum if you want my answer.

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Bronze Markawneil
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Posted by awneil: Sun. Jun 14, 2015 - 01:30 PM (Reply to #2)
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Thanks, Alex.

 

That's the way I'd hoped it'd be. Shame they couldn't have made it clear in the documentation.

angry

So I've scratched Atmel from some IoT/M2M demos I'm doing next week.

 

alexru wrote:
realistically there is no way to access SPI or TWI connection anyway.

Why do you say that?

I've had the SPI working on D20/D21/R21 Xpro.

 

I think ARM questions belong here.

Indeed. The separation is ridiculous.

 

It is claimed that this forum software was chosen because of its flexibility - so I really don't see why they don't just add a set of ARM forums here...

 

Top Tips:

  1. How to properly post source code - see: https://www.avrfreaks.net/comment... - also how to properly include images/pictures
  2. "Garbage" characters on a serial terminal are (almost?) invariably due to wrong baud rate - see: https://learn.sparkfun.com/tutorials/serial-communication
  3. Wrong baud rate is usually due to not running at the speed you thought; check by blinking a LED to see if you get the speed you expected
  4. Difference between a crystal, and a crystal oscillator: https://www.avrfreaks.net/comment...
  5. When your question is resolved, mark the solution: https://www.avrfreaks.net/comment...
  6. Beginner's "Getting Started" tips: https://www.avrfreaks.net/comment...
Last Edited: Sun. Jun 14, 2015 - 01:44 PM
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alexru
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Posted by alexru: Sun. Jun 14, 2015 - 05:11 PM (Reply to #3)
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awneil wrote:
Why do you say that?

I've had the SPI working on D20/D21/R21 Xpro.

I'm talking about SPI and TWI (and GPIO as well) going to the EDBG, which you in theory should have access to via USB/HID interface. None of this stuff was ever documented though, but it is present on every Xpro schematic.

 

Also, what is the use case for having separate voltage for IO on a micro controller? The only thing comes to mind is interfacing with FPGAs, but who does that?

NOTE: I no longer actively read this forum. Please ask your question on www.eevblog.com/forum if you want my answer.

Last Edited: Sun. Jun 14, 2015 - 05:15 PM
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